Conductivity,SurfaceTension,andComparativeAntibacterial ...

Research ArticleConductivity Surface Tension and Comparative AntibacterialEfficacy Study of Different Brands of Soaps of Nepal

Narendra Kumar Chaudhary Arush Bhattarai Biswash Guragain and Ajaya Bhattarai

Department of Chemistry Tribhuvan University Mahendra Morang Adarsh Multiple Campus Biratnagar Nepal

Correspondence should be addressed to Ajaya Bhattarai bkajayayahoocom

Received 18 June 2019 Revised 27 January 2020 Accepted 26 February 2020 Published 15 April 2020

Academic Editor Elena Gomez

Copyright copy 2020 Narendra Kumar Chaudhary et al -is is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in anymedium provided the original work isproperly cited

-e current study aims to evaluate the solution properties and antibacterial efficacy study of five different brands of toilet soaps ofNepal such as Okhati (OKT) Lifebuoy (LFBY) Lux (LX) Liril (LRL) and Chiuree Neem (NM) -e evaluation of critical micelleconcentration (CMC) and their thermodynamics and surface properties are also reported -is study was further extended toevaluate antibacterial efficacy against three pathogenic bacteria such as Staphylococcus aureus (S aureus) Escherichia coli (E coli)and Proteus vulgaris (P vulgaris) by disc diffusion technique and it was done at four different concentrations of soap -ebioactive ingredients present in them provide antibacterial potency to cure various skin problems caused by bacterial pathogensSimilarly the antibacterial potency of LFBY was found higher than other soaps Based on these studies we can simply take LFBYsoap at the highest rank in regards to antibacterial sensitivity

1 Introduction

-e prevalence of skin diseases is increasing due to the directinteraction of transient microorganisms on the skin surfaceIf not degermed properly they penetrate the human bodyand cause internal infection So degerming of the body is amatter of prime importance to maintain personal hygiene-e simplest and effective way to prevent the spread ofmicrobial infections is proper cleaning and washing of bodyparts using soap [1] -e soap contains surfactants andantimicrobial ingredients to enhance the cleansing actionand wash pathogenic organisms It is one of the mild de-tergents [2] which is effective in removing contaminantsincluding bacteria fungus or viruses Soap solution actsupon the alien particles emulsifies and suspends the dirtoil and germs allowing them to be washed off For furtherprotection either chemical or plant-based antibacterialagents are used in soaps to enhance biofunctional activitiesChemicals like triclocarban and triclosan are added in soapand personal care products alike as antibacterial ingredients-ese antibacterial ingredients of soap are effective in

preventing communicable diseases [3] 65ndash85 microbialremoval from human skin is due to the application of an-tibacterial soap [4 5]

A study by Riaz et al [6] revealed greater effectiveness ofantibacterial soaps against pathogenic bacteria relative toplain soaps Typically antimicrobial products are used tostay healthy However there are two risks of their use thefirst is deliberately accepted chemical exposure and the nextis the increase of antibiotic-resistant pathogens which ul-timately makes the microbial treatment more difficult Asper a review Aiello et al [7] observed that the available datadid not support the effectiveness of triclosan for reducingsymptoms of infectious disease which is a common anti-bacterial used in soap As recommended by the Food andDrug Administration (FDA) the effectiveness of the anti-septic ingredients should be studied reflecting exposure timeand real-life situations Kim et al [3] studied the antibac-terial effect of some plain and antibacterial soaps against 20bacterial strains proposed by the FDA Under real-lifeconditions no significant differences in bactericidal effectswere found Furthermore in the year 2008 by Aiello et al [8]

HindawiJournal of ChemistryVolume 2020 Article ID 6989312 13 pageshttpsdoiorg10115520206989312

and also in the year 2015 by Kim et al [3] supported the ideathat antibacterial soaps are not so significant compared tobland soaps Added antibacterial agents have very little timeto show bactericidal action therefore the mechanical aspectof friction is of critical importance In the food and healthcare industries hand-washing practices matter themost-eactivity of soap friction and rinsing are crucial for effectiveantibacterial action [9 10]

Not all bacteria are pathogenic and bactericides are notrequired to be used on daily usable products Antibacterialagents are used in many personal care products such as soapstoothpaste lotions shampoos and other household productssuch as kitchenware clothing furniture and toys Irre-sponsible and abusive use of antimicrobial products is closingthe antibiotic era -ere have been many outbreaks of food-borne diseases and nosocomial infections due to hand con-tamination Ogba et al [1] reported S aureus followed by Ecoli to be the most common isolates on the hands of primaryschool children in Nigeria S aureus and E coli are associatedwith skin infections and food poisoning respectively [11]

Nepal being rich in flora and diversity a lot of amazing lifeforms are planted here Traditionally plant extracts are usedfor many purposes including food preservation flavor en-hancement health improvement and more Plant oils are oldtested and reliable sources for the treatment of various skindiseases and are therefore used in body and skincare products[12] Plant-derived compounds represent an unlimited sourceof safe effective and environmentally friendly antimicrobialsDue to the fascinating antimicrobial effects nontoxic natureand low cost many self-care products like lotions toothpastesoaps etc manufactured here have been enriched with theextracts of natural products [13] -e herbal-based cosmeticsare rich in phytochemicals such as vitamins proteins tanninsterpenoids and other bioactive ingredients that possess an-tioxidant anticancer antimicrobial and other beneficial ac-tions [14] Low toxicity to users and the environment providesa great deal of beauty and medicinal effects [15] Of the fivesoaps selected two (OKT and NM) contained only herbalproducts while LX and LRL contained plant extracts addedwith chemicals

-e present paper aims to evaluate some solution be-havior and in vitro antibacterial efficacy of five toilet soapformulations containing both herbal and chemical-basedingredients -e soap contains surfactants that lower thesurface tension of the solution Lower surface tension hastaken advantage of improved cleansing action by easy dif-fusion on the skin surface [16] With the increase in thepurity of soap there is a profound effect in the electricalconductivity and the presence of impurities can cause someconstraints on the mobility of charge of the soap solution[17 18] Most plant extracts used in herbal-based soaps havemedicinal value In addition the antibacterial efficacy ofnatural herbal extracts in soap was compared and evaluated

2 Experimental

21Materials andMethods All chemicals and reagents usedfor this experiment were of analytical reagent grade Fivesoaps were selected for assessment and were purchased from

the local market of Biratnagar Nepal -ese soap formu-lations are coded as Lux (LX) Lifebuoy (LFBY) Liril (LRL)Okhati (OKT) and Chiuree Neem (NM) -eir ingredientsare listed in Table S1 A Kruss K20S Easy Dyne ForceTensiometer was employed to measure the surface tensionby the ring detachment technique using a platinum ring withthe correction of Harkins and Jordan -e AutorangingConductivityTDS meter TCM 15+ was used to measure thespecific conductance of soap solutions For the antibacterialefficacy assessment the glassware was washed with tripledistilled water and dried in the oven before use Pyrogen-freedistilled water was used for the preparation of solutions andwas made at their four different concentrations such as 1 011 02 1 04 and 1 08 To explore the solution propertiesall soaps solutions were prepared at 02mgmL concentra-tion and kept as stock solutions Further the internal di-lution in tap water was preformed 15 times for all -isstudy carried in tap water was to mimic the daily householdprocedure

22 Antimicrobial Assay -e antibacterial sensitivity of thesoap was studied by the disc diffusion technique -reedifferent bacterial pathogens E coli S Aureus and Pvulgaris which are known to reside on the body surface andgive evidence to cause piles of diseases are deployed in thisevaluation -e bacterial culture was revived by seedingsome well-isolated colonies of pathogens in nutrient brothand incubated for two hours -e sterile Mueller-Hintonagar solution prepared by standard technique was left tocongeal in the sterile Petri plates -e broth of previouslyseeded bacterial culture was spread in the media and thewell-sterilized paper discs of 5mm diameter (Whatman no 1)impregnated with test samples were stuck on the plates Forcomparison of efficacy a disc of antibiotic (amikacin 30 μgdisc) was also installed -e plates were incubated at 37degCfor 24 hours -e antibacterial sensitivity was then assessedby measuring the diameter of the zone of inhibition in mmAll the procedures were repeated three times to reduceerrors

3 Results and Discussion

31 Conductivity and )ermodynamic Properties -e spe-cific conductance of surfactants depends on the nature ofions formed after ionization the nature of the solvent usedthe temperature and the presence of additives like salts [19]-e variation of specific conductivity with the concentrationof soap is well demonstrated in Table 1 and Figure 1 LX hasthe lowest specific conductivity (0404mScm) while LFBY(0454mScm) has the highest -e decrease in specificconductivity with dilution is due to the replacement of ionsby colloidal particles which although conducting has alower equivalent conductivity than the ions from which theyare formed Colloidal particles are thus formed in very lowconcentrations [20] Upon dilution the specific conductivityof all soaps has significantly reduced On the overall view wecan take the specific conductivity of LFBY NM and OKTashigher values and LRL and LX as lower values

2 Journal of Chemistry

32 CriticalMicelle Concentration -e specific conductanceof soaps in water for the calculation of the CMC at 30315Kis shown in Figure 1-e specific conductivity increases withthe increase of concentration with a certain slope But at aparticular concentration the slope changes -e breakingpoint of two linear variations is called critical micelleconcentration (CMC) A degree of dissociation (α) is ob-tained from the ratio of postmicellar (S2) to the premicellarslope (S1) -e variations in the pre- and postmicellar slopeson the plots of specific conductance with a concentration ofthe solution of soaps are given in Table 2

33 Correlation of (κoκCMC) with Soaps In the year 2012Mukhim and Ismail [21] proposed the ratio of the solventsurface tension to the limiting surface tension at the CMC

(cocCMC) to describe the solvophobic effect [22] But herewe tried to see the ratio of solvent conductance to theconductance at the CMC with soaps Figure 2 shows thevariation in the ratio of the solvent conductance to theconductance at the CMC with soaps -e fitting is from thepolynomial equations having correlation coefficients r2 1-e highest ratio value is for LX (5) whereas the least ratiovalue is for LFBY (1) -e concave curve of (κoκCMC) withsoaps is observed (Figure 2) Hence the higher the ratiovalues of (κoκCMC) the better the cleansing action

We used the variation of X-axis of soaps as LFBY (1) NM(2) OKT (3) LRL (4) and LX (5)

34 Correlation of Slopes with Soaps -e premicellar slope(S1) sharply decreases with LFBY NM OKT LRL and LX-e fitting of the data was done by the polynomial equationwith the correlation coefficient r2 1-e postmicellar slope(S2) increases monotonously with LFBY NM OKT LRLand LX -e fitting of the data was done in the quadraticequation with the correlation coefficient r2 1 but it lookslike linear variation (Figure 3)

All soaps have shown the highest pre-CMC slopes andthe lowest post-CMC slopes leading to the lowest degrees ofdissociation (Table 2) -ese slopes are so sensitive that theydetermine the degrees of dissociation CMC and otherthermodynamic parameters-e CMC obtained for all soapsfrom conductivity measurements in water at 30315K isgiven in Table 2 It indicates that CMC increases with LFBYNM OKT LRL and LX -e increase of CMC and α withinthe ascending order of LFBY NM OKT LRL and LX in theaqueous medium is shown in Table 2 -e reason for thehighest CMC on LX is due to the presence of the hugenumbers of ingredients that slow down the dielectric con-stant of water and hence CMC increases Such an increase ofCMC with the decrease of the dielectric constant of water inthe presence of external compounds was also found in theliterature [23] It is well known that the presence of variouscompounds diminishes aggregation number of the micelleswhich then causes an increment in the electrostatic repulsionbetween the cationic head group of LX and leads to a re-duction in the electrical charge density at the micellarsurface -is may be the reason for the increase in α [24]

CMC increases sharply with ascending order of LFBYNM OKT LRL and LX (Figure 4) -e nature of the curvelooks like somehow linear but concave fitting by the poly-nomial equation of correlation coefficient r2 1

-e increases sharply with ascending order of LFBYNM OKT LRL and LX (Figure 5) -e nature of the curvelooks like concave fitting by the polynomial equation of thecorrelation coefficient r2 1

-e free energies of micelle formation of soaps arecalculated by a pseudophase separation model [23] and thedata are given in Table 2

ΔGom (2 minus α)RT ln XCMC (1)

where XCMC R and T have usual meaningsΔGo

m is negative with all soaps and becomes less negativefrom the ascending order of LFBY NM OKT LRL and LX

Table 1 Concentration against specific conductivity of differentsoap samples

Conductivity (mScm)SN

Concentration(mgmL) OKT NM LFBY LRL LX

1 0200 0441 0448 0459 0429 04002 0166 0434 0443 0454 0421 03933 0143 0430 0438 0449 0416 03864 0125 0425 0435 0445 0412 03805 0111 0423 0433 0444 0409 03786 0100 0419 0428 0441 0407 03727 0090 0417 0425 0438 0402 03678 0083 0413 0424 0436 0398 03639 0076 0409 0423 0435 0392 035710 0071 0403 0419 0433 0387 035511 0066 0398 0416 0432 0385 035212 0062 0395 0413 0430 0384 034813 0058 0391 0409 0427 0382 034514 0055 0388 0405 0425 0380 034315 0052 0385 0401 0421 0376 034116 005 0382 0399 0418 0375 033917 Tap water 0383

035

040

045

0 005 010 015 020 025[C] (mgmL)

κ (m

Scm

)

Figure 1 Graph depicting the variation of specific conductancewith the concentration of different soaps LFBY (closed triangles)NM (closed circles) OKT (triangles) LRL (circles) and LX(squares)

Journal of Chemistry 3

(Table 2) -e nature of the curve looks like concave fittingby the polynomial equation of correlation coefficientr2 = 1(Figure 6) -e higher negative ΔGo

m indicates that themicellization process is spontaneous and becomes lessspontaneous from the ascending order of LFBY NM OKTLRL and LX (Table 2) Less negativeΔGo

m indicates co-solutedoes not facilitate the micellization [25]

35 Model for Critical Micelle Concentration We are veryfamiliar with the CMC determination from the intersectionof the two straight lines drawn before and after the break intheK against soap concentration (c) plot (Figure 7) Here wehave also used the concept of Carpena et al [26] for our dataof soaps Let us take the derivative of the sigmoid type andcan be described by using a Boltzmann-type sigmoid that hasthe following equation

Table 2 Values of premicellar slope (S1) postmicellar slope (S2) degree of dissociation (α) critical micelle concentration (CMC) and Gibbsfree energy of micellization (ΔGo

m) of LFBY NM OKT LRL and LX in aqueous medium at 30315K

Soaps S1 (mS cmminus1mlmiddotmgminus1) S2 (mS cmminus1mlmiddotmgminus1) α CMC (mgmiddotmLminus1) ΔGom(kJmolminus 1)

LFBY (1) 114 0187 0164 006295 minus3137NM (2) 110 0194 0176 007174 minus3057OKT (3) 104 0211 0203 008323 minus2993LRL (4) 0658 0216 0328 009502 minus2728LX (5) 0647 0243 0376 01089 minus2593-e error limits of α CMC and ΔGo

m are within plusmn 4 plusmn 4 and plusmn 5 respectively

0

04

08

12

1 2 3 4 5

y = ax5 + bx4 + cx3 + dx2 + ex + f max dev 149E ndash 8r2 = 100

a = 602E ndash 4 b = ndash000670 c = 00242 d = ndash00268f = 0196

y = ax5 + bx4 + cx3 + dx2 + ex +f max dev 136E ndash 8 r2 = 100

a = 000962 b = ndash0103 c = 0353 d = ndash0422f = 130

S2

S1

Soaps

Slop

e (m

scm

lowast m

Lmiddotm

gndash1)

Figure 3 Variation of slope versus soaps in premicellar slope (S1)and postmicellar slope (S2) regions

006

007

008

009

010

011

1 2 3 4 5

y = +749E ndash 4x2 + 000703x1 + 00551max dev 361E ndash 4 r2 = 100

Soaps

CMC

(mgmiddot

mLndash1

)

Figure 4 Variation of CMC versus soaps

090

095

100

1 2 3 4 5

y = ax3 + bx2 + cx + d max dev 874E ndash 4 r2 = 100a = 000398 b = ndash00283 c = 00784 d = 0830

Soaps

κ oκ

cmc

Figure 2 Variation of (κoκCMC) with different soaps LFBY (1)NM (2) OKT (3) LRL (4) and LX (5)

015

020

025

030

035

040

1 2 3 4 5


a = ndash000248 b = 00264 c = ndash00894 d = 0106f = 0123

Soaps

α

Figure 5 Variation of α versus soaps


κ( c) A1 minus A2

1 + e cminuscoΔc( )+ A2 (2)

On integrating equation (2) we get

K(c) K(0) + A1c + Δc A2 minus A1( 1113857ln1 + e cminus coΔc( )

1 + e minuscoΔc( )1113888 1113889 (3)

where K0 A1 A2 and Δc are the specific conductivity of thesolution at zero concentration of the soap premicellar slopepostmicellar slope and width of the transition respectively-is is one of the most efficient methods which is being usedrecently especially for the micellization of soap whereprobably a weak curvature is obtained -e central point onthe width of the transition (co) corresponds to CMC and thedegree of counterion dissociation (α) can be determinedfrom the ratio of the postmicellar slope to the premicellarslope as α A2A1 [23]

A smaller value of Δc means abrupt transition (micel-lization is highly cooperative) while its higher value shows agradual transition (micellization process is less cooperative)In the analysis K(0) was set equal to zero because theconductivity of the solvent was substracted corresponding toeach data point Data fitting was carried out bymaking use ofinitial guess values of A1 A2 co and Δc in equation (3) tocalculate an approximate value of conductivity K

approxc

corresponding to each surfactant concentration Chi-squareχ2 the sum of the squares of deviations of approximateconductivity from the experimental values is defined as

χ2 1113944N

i1Ki minus K

approxi1113858 1113859

2 (4)

(where N is the number of data points and Ki and Kapproxi

are the experimental conductivity and approximate con-ductivity at a given soap concentration respectively) wasminimized with respect to these parameters and their valuescorresponding to the minimum were then used as the newset of guess values in an iterative procedure till χ2 effectivelystopped decreasing indicating convergence of input andoutput parameters -e minimized value of χ2 gives maxi-mum likelihood estimate of model parameters Equation (3)being nonlinear in the parameters a computer program forthe nonlinear least-squares fitting of data as described byPress et al [27] and making use of the Levenberg-Marquardtalgorithm was written with necessary modification toperform the iterative procedure for the optimization ofparameters -e final set of values K0 A1 A2 and Δc whenχ2 effectively stopped decreasing was taken as their best-fitparameters Figure 7 shows the representative conductivityconcentration plot of LFBY in water at 30315K

-e CMC obtained from the conventional procedure is006295mgml whereas CMC from the first derivative is0064mgml (equation 2) and the CMC from the integralequation (3) is 00625mgml Micelles only form when theconcentration of soap is greater than the CMC -ereforethe higher the concentration the more micelles there are-e cleaning action is associated with the CMC In ourstudy we have seen that the formation of the micelles ishighest for LX At this point the LX will have the highestnumber of micelles to wet the substrate -e cleaning is noteffective due to fewer micelle formation in the cleaningsolution as it is superconcentrated Fewer micelles andfoaming in the cleaning solution are not beneficial in thecleaning application [28]

36 Surface Tension and Surface Properties Soaps are usuallyamphiphilic organic compounds that have the ability tochange the interfacial properties of liquids in which they arepresent even at a very low quantity -e lower the surfacetension higher will be the cleansing action and vice versa[29] We want to study the micellization behavior of soaps inwater at 30315K from the surface tension study -e valuesof critical micelle concentration (CMC) maximum surfaceexcess concentration (Γmax) area occupied by per surfactantmolecule (Amin) surface pressure (πCMC) solution surface

01

03

05

07

0 005 010 015 020cmc

[C] (mgml)

κ (m

Scm

)

Figure 7 Experimental data of conductivity (circles) againstconcentration the break point of two straight lines is the CMCK(c) and their corresponding first derivative (squares) κ( c) forLFBY at 30315K -e lines are the best fits of data

ndash32

ndash30

ndash28

ndash26

ndash24

1 2 3 4 5Soaps

∆Gdeg m

(kJm

olndash1

)

y = ax5 + bx4 + cx3 + dx2 + ex + f max dev386Endash8 r2 = 100a = ndash00600 b = 0671 c = ndash245 d = 325f = ndash328

Figure 6 Variation of ΔGom versus soaps


tension (cCMC) solvent surface tension (co) free energies ofadsorption (ΔGo

ads) efficiency of adsorption (pC20) effectiveGibbs free energy (ΔGo

eff ) relation between Amin and πCMCthe correlation of slope (dcdlog C) (cocCMC) (ΓΓmax)(ΔGo

adsΔGom) and (CMCpC20) with soaps are also in-

cluded in this study -e experimental data of surfacetension of soaps are compared with the theoretical model

As we talk about soaps we see the existence of a hy-drophilic head and a hydrophobic tail All classes of soapsare mostly used in all areas of the present world because oftheir unique properties It is well known that the inter-action between the soap molecules and water moleculesresults in a hydrophilic affinity towards the head whereasthe hydrophobic affinity towards the tail As a result themolecules are oriented on the surface of the water tailaligning towards the air -is behavior is very common forall classes of soaps As we increase the concentration ofsoap the interaction between the soap molecules and watermolecules also increases and the formation of aggregationtakes place Such aggregates are known as micelles [30]-emicelles play a very important role to make the soap sig-nificant in the related fields such as pharmaceutical andtextile industries In the micelles there is always a balancebetween hydrophobic and hydrophilic forces [31] Somefactors directly affect the morphological behavior of themicellar system -ey are additives temperature as well assolvent composition [32]

Figure 8 depicts the different initial values of surfacetension among different soaps -e surface tension of LXbeing 529mNm is the least and that of LFBY (596mNm)is the highest At all concentrations the surface tension ofLX is relatively low and highest for LFBY (Table 3) All thesoaps have shown a general pattern of regular increment ofsurface tension upon dilution Also we have seen that thesurface tension of soap at first decreases with increasingconcentration of soap and then follows a sigmoid curvebetween surface tension (c) and log[surfactant] -ere is aformation of a visible break on the sigmoidal curve afterwhich the surface tension remains approximately constant-e breaking point is called the CMC [33]

Such studies of soaps are scarce but only the surfacetension of shampoos is studied [34] without explanation ofthe micellization behavior of shampoos Our first aim is toinvestigate the aggregation behavior of soaps in water at30315K in detail and the second aim is to compare ourexperimental data of surface tension of soap with the the-oretical model-e surface tension of soap solutions in waterwas plotted against the concentration to get the CMC valuesat 30315K -e representative figure (Figure 9) shows thevariation of the surface tension of soap in water at 30315K

From the plot of surface tension with the concentrationof soap solution the following surface properties are cal-culated [35] -e maximum surface excess concentration atthe air-water interface Γmax has been calculated by applyingGibbs isotherm

Γmax minus1

2303nRT

dc

dlog C1113890 1113891

TP

(5)

where c denotes the surface tension R is the gas constant(8314 Jmiddotmolminus1middotKminus1) T is the absolute temperature C is thesoap concentration and (dcdlog C) is the slope of the c

versus log C plot taken at CMC -e constant n takes thevalues 2 for conventional soap where the soap ion and thecenter line are univalent -e area occupied per soapmolecule (Amin) at the air-water interface has been obtainedby

Amin 1

NΓmax (6)

where N is Avogadrorsquos number-e value of the surface pressure at the CMC (πCMC) is

obtained as

πCMC co minus cCMC (7)

50

55

60

65

70

ndash14 ndash12 ndash10 ndash08 ndash06Log [C]

γ (m

Nm

)

Figure 8 Graph representing the dependence of surface tensionwith the concentration LFBY (closed circles) NM (squares) OKT(circles) LRL (triangles) and LX (closed squares)

Table 3 Concentration versus surface tension of different soapsamples

Surface tension (mNm)S N Concentration (mgmL) NM OKT LRL LFBY LX1 0200 585 571 549 596 5292 0166 589 574 558 601 5353 0143 592 580 569 604 5384 0125 599 586 574 610 5465 0111 605 592 577 616 5526 0100 609 598 589 620 5577 0090 616 607 593 625 5668 0083 621 615 599 633 5749 0076 630 618 607 638 58010 0071 641 623 614 641 58611 0066 645 630 624 648 59312 0062 651 638 630 656 59813 0058 657 644 635 661 60614 0055 660 650 640 664 61415 0052 665 655 647 672 61816 0050 670 662 650 678 62317 Tap water 7134


where co and cCMC are the values of surface tension of waterand the soap solution at the CMC respectively

-e standard free energy interfacial adsorption at the airsaturated monolayer interface can be evaluated from therelation [36]

ΔGoads ΔGo

m minusπCMC

Γmax (8)

Amin refers to the property associated with the soapmonolayer at the airwater interface -e maximum surfaceexcess concentration at the airwater interface (Γmax) areaoccupied per surfactant molecule (Amin) at the air-waterinterface surface pressure at the CMC (πCMC) and thestandard free energy interfacial adsorption (ΔGo

ads) of soapssolutions in water at 30315K are calculated respectivelyand the values are listed in Table 3

Chakraborty et al [37] calculated the CMC (mM) ofCTAB at 25degC by (0959) conductivity and by (0883) ten-siometry Similarly our CMC of soaps at 30315K byconductivity and tensiometry almost matched each other-e data suggest that Γmax as well as πCMC values decreasewith soaps at 30315K indicating the low population of soapmolecules at the interface due to the addition of ingredientsNegative values of ΔGo

ads indicate that the adsorption of soapmolecules on the surface is spontaneous and this phe-nomenon is more spontaneous than the micellization due tolarger negative value than ΔGo

m -e values of ΔGoads become

more negative with soaps at 30315K that shows morespontaneity of adsorption of soap molecules on the surface

37 Variation of the Slope of Surface Tension Curve withSoaps -e slope of the surface tension curve (Figure 10) ofsoaps solution in water at 30315K gives various informationabout the surface properties of soaps solution [33] It is seenthat the slopes increase with soaps in the order of LFBY NMOKT LRL and LX

38 Correlation of (coccmc)with Soaps Figure 11 shows thevariation of (cocCMC) with soaps at 30315K -e values of(cocCMC) increase in the order of LFBY NM OKT LRLand LX -e nature of the curve is concave fitting by thepolynomial equation of the correlation coefficient r2 1

39 Correlation of ΔGoads with Soaps Gibbs energies of ad-

sorption of soaps in water show the unique variation at30315K (Figure 12) ΔGo

ads monotonously decreases withsoaps in the order of LFBY NM OKT LRL and LX -enature of the curve is the combination of convex-concave-convex fitting by the polynomial equation of correlationcoefficient r2 1

310 Correlation of ΔGoeff with Soaps -e difference between

ΔGoads and ΔG

om is called effective Gibbs free energy (ΔGo

eff )-e curve of ΔGo

eff sharply decreases with convex variationby the addition of various soaps in the order of LFBY NMOKT LRL and LX at 30315K (Figure 13) fitting by thepolynomial equation of correlation coefficient r2 = 1 It is

50

55

60

65

70

ndash150 ndash125 ndash100 ndash075 ndash050

LX

y = ndash182x1 + 378 max dev 118E ndash 4 r2 = 100


Log [C]

γ (m

Nm

)

Figure 9 Plot of surface tension versus concentration of a rep-resenting soap (LX) solution at 30315K

ndash28

ndash24

ndash20

ndash16

ndash12

1 2 3 4 5

y = ax5 + bx4 + cx3 + dx2 + ex + f max dev 363E ndash 8 r2 = 100a = ndash0233 b = 275 c = ndash109 d = 157

f = ndash352

Soaps

Slop

e (m

Nm

ndash1 lowast

lnm

Lmiddotm

gndash1)

Figure 10 Variation of the slope with soap solutions

10

11

12

13

1 2 3 4 5

y = ax5 + bx4 + cx3 + dx2 + ex + f max dev 497E ndash 9 r2 = 100a = 000107 b = ndash00123 c = 00476 d = ndash00561

f = 112

Soaps

γ oγ

cmc

Figure 11 Variation of (coccmc) with soaps


also observed that the values of ΔGoeff decrease with an

increase in head group polarity of soaps indicating thataggregation is more favored than the adsorption processand also less energy is required for the aggregation process[38]

311 )e Relation between Amin and πCMC πCMC is ameasure of the cohesive force in the surfactant film whereasAmin describes the ldquoorientationrdquo of the surfactantrsquos moleculein an aqueous solution We also plotted the curve ofπCMCAmin with πCMC of LFBY NM OKT LRL and LX-enature of the curve at first increases sharply for LFBY andNMand then the curve monotonously increases for OKT andagain sharply for LRL Eventually the convex curve was seenfrom LRL to LX at temperature 30315K (Figure 14) fitting bythe polynomial equation of correlation coefficient r2 1

312 Correlation of (ΓΓmax) with Soaps Applying theFrumkin isotherm equation provided in the literature [39] itwas confirmed that the concentration value at which c ofwater is minimized by 20mNm and the ratio of the Gibbs

surface excess concentration (Γ) to the maximal (Γmax) iswithin 084 to 0999

We have calculated the (ΓΓmax) values for soaps fromthe equation used in the literature [39]

πcmc minusRTΓmax ln 1 minusΓΓmax

1113888 1113889 (9)

Our values of (ΓΓmax) for soaps perfectly matchedwithin the range of the literature [39]

-e values of (ΓΓmax) increase sharply for soaps in theorder of LFBY NM OKT LRL and LX at 30315K (Fig-ure 15) fitting by the polynomial equation of correlationcoefficient r2 1 and finally the curve looks like convex-ehighest value of (ΓΓmax) shown for LX and the lowest forLFBY But the values of (ΓΓmax) for all soaps are within therange of 066 to 099

313 Correlation of (ΔGoadsΔGo

m) with Soaps -e observedΔGo

ads values are higher than ΔGomin values indicating the

adsorption at the air-solution interface is more favorable thanthe formation ofmicelles in the bulk solution [40]-e ratio of(ΔGo

adsΔGom) is found in the range of 11 to 114 for LFBY

NM OKT LRL and LX (Figure 16) -e variation of thecurve looks concave fitting by the polynomial equation of thecorrelation coefficient r2 = 0997 -e value of (ΔGo

adsΔGom)

for LX is the highest and the lowest for LFBY at 30315K

314 Correlation of (CMCpC20) with Soaps -e ratio ofCMC to pC20(CMCpC20) is an interesting study Such typeof work was observed by Niranjan and Upadhyay in 2010[41] -e variation of the curve for soaps increases sharplyfor LFBY NM OKT LRL and LX (Figure 17) fitting by thepolynomial equation of correlation coefficient r2 = 1 Natureof the curve looks somehow like convex

315 )eoretical Model -e surface tension data for soapsolution at 30315K were fitted with a nonlinear least-squaresregression analysis using the Szyszkowski equation for the

ndash365

ndash355

ndash345

ndash335

1 2 3 4 5


f = ndash348

Soaps

∆Ga0 ds

(kJmiddotm

olndash1

)

Figure 12 Variation of ΔGoads with soaps

ndash12

ndash10

ndash8

ndash6

ndash4

ndash2

1 2 3 4 5


f = ndash204

Soaps

∆Ge0 ff

(kJmiddotm

olndash1

)

Figure 13 Variation of ΔGoeff with soaps

0

5

10

15

20

5 10 15

y = ax6 + bx5 + cx4 + dx3 + ex2 + fx + g max dev 346E ndash 8 r2 = 100

a = 614E ndash 5 b = ndash000390 c = 00857 d = ndash0706f = 287 g = ndash101

π cm

cAm

in

πcmc

Figure 14 Variation of πCMCAmin with πCMC


premicellar region whereas for the postmicellar region thelinear variation was noted It is also well known that verysmall concentrations of surface-active impurities affect the

transition region around the CMC By analyzing the surfacetension versus concentration data for the system in thepremicellar region is the subject of our interest [42] Heresoap contains cation and anion So we denote the mean ionicactivity coefficient of the solution by cplusmn and the followingrelations can be written by using the DebyendashHuckel equationto relate the activity of the surfactant to the ionic strength (I)

asoap cplusmnCanionfreecplusmnCCationfree

I [Soap]total

log cplusmn( 1113857 minus0509I05

1 + 131I05( )+ 0049I

(10)

where Canionfree and CCationfree are molar concentrations of thefree anion and cation respectively It can be mentioned thatthe complex formation in the premicellar region does notaffect the ionic strength -e combination of the Langmuirmodel for surface adsorption with the Gibbs equation c canbe explained by the Szyszkowski equation

c c0 minus bln 1 + casoap1113872 1113873 (11)

where b ΓinfinRT (RTω) Γinfin is the value of surface excessof the soap when a complete monolayer is present and ω isthe cross-sectional area of the soap molecule at the surfaceper mole [43] c is related to the equilibrium constant Byplotting c versus asoap we get the fitting parameters asb(501 plusmn 030m middot Nmminus 1) and c(459 plusmn 01 (mgml)minus2) withcorrelation coefficient (r2 = 0996) as shown in Figure 18 forLX It is interesting to see that ongoing from LX to LRLOKT NM and LFBY there is an increase of b but thedecrease of c -e correlation coefficient of the experimentaldata of all soaps fits around (r2 = 0996) with the model Butwe have shown in Figure 18 the more experimental dataabove the CMC of LRL OKT NM and LFBY to makesymmetry in the graph so we have observed the correlationcoefficient of fits look more good to less good (Figure 18)ongoing from LX to LRL OKT NM and LFBY

-e mean square average deviation δc between theexperimental (exp) and the predicted model (model) surfacetension values is minimized as the relation [44]

δc

1113936Ni1 cexpi

minus cmodeli1113872 11138732

N

1113971

(12)

where N is the number of data points -e above model cansay ldquosuccessfulrdquo if δc is the same as or lower than the esti-mated error in the surface tension measurements taken to bewithin 1mmiddotNmminus1 [44] In our case δc 097mmiddotNmminus1 -e fitis successful So we are also interested to see theminimal valueof the surface tension of aqueous solution of soap at 30315Kwith the help of the equation described elsewhere [45]

Γmax

ΓinfincCMC+ 1 minusΓmax

Γinfin1113874 1113875cwater ccal (13)

where Γmax 000156 (Table 4) Γinfin 0019877 asb ΓinfinRT cCMC 552 for LX and cwater 7134 and thenthe value of ccal turns out to be 6574mmiddotNmminus1 -is issomehow higher than the measured one (552mmiddotNmminus1)

10

11

12

13

14

1 2 3 4 5

y = ax3 + bx2 + cx + d max dev 000969 r2 = 0997a = ndash917E ndash 4 b = 00256 c = ndash00475 d = 111

Soaps

∆G0 ad

s∆G

m0

Figure 16 Variation of (ΔGoadsΔG

om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5

y = ax4 + bx3 + cx2 + dx + e max dev 287E ndash 4 r2 = 100a = ndash000167 b = 00198 c = ndash00832 d = 0159

Soaps

CMC

pC20

Figure 17 Variation of (CMCpC20) with soaps

06

07

08

09

10

0 01 02 03 04

y = ax3 + bx2 + cx + d max dev 000413 r2 = 100a = ndash449 b = 158 c = 0900 d = 0660

Soaps

ΓΓ m

ax

Figure 15 Variation of (ΓΓmax) with soaps


Based on Van Oss concept [46] c of water changes in therange of soap concentration in the bulk phase correspondingto the saturated monolayer at the water-air interfaceAccording to this concept 30 of c of water results from theLifshitz-Vander Waals and 70 from the hydrogen bondintermolecular interaction It may be possible that the in-volvement of soap molecules in the surface layer causespartial breaking of hydrogen bonds which lowers c of water

Using the value of c the standard Gibbs energy of ad-sorption can be calculated as [47]

ΔGoads minus RT ln(c) (14)

where R 8314 Jmiddotmolminus1middotKminus1 is the gas constant andT 30315K-e value ofΔGo

ads is equal tominus1545 kJmiddotmolminus1 forLXWe are interested to compare the standard Gibbs energy ofadsorption for LX at 30315K with the various equations

Let us take the equation which has the degree of dis-sociation (α) critical micelle concentration (CMC) and areaoccupied by per surfactant molecule (Amin) and surfacepressure (πCMC) [48]

ΔGoads 2303(2 minus α)RT log CMC minus 06023πCMCAmin

(15)

Here α 0376 from Table 3 of LX in water at 30315K byconductivity methods and the rest values of Amin and πCMCwas taken from Table 4 then the value of ΔGo

ads becomesminus100288 kJmiddotmolminus1 From the above discussion we observe aminimum in the surface tension concentration curve for an

aqueous solution of LX and it is widely accepted that theminimum is caused by the existence of a highly surface-activeimpurity in the soap solution [49] Hence the surface tensionof the different soap solutions depicts that LX has the best andLFBY has the least cleansing action

316 Antibacterial Sensitivity Screening Human skin is arich habitat of pathogenic microbes Antibacterial screeningof soap solutions was performed at four different concen-trations and the data revealed pathetic conditions thatcontrasted with their commercial advertisements In vitroantibacterial study of soaps was conducted against threedifferent bacterial pathogens such as S aureus E coli and Pvulgaris by the standard KirbyndashBauer paper disc diffusiontechnique [50] -e antibacterial data are summarized in

40

50

60

70

00015 00030 00045 00060 00075 00090

y = 7134 + (b ndash 7134)lowastclowastxlowast(1 + clowastx)ndash1 max dev 0721 r2 = 0986b = 520 c = 248





aSOAP

γ

Figure 18 Variation of c with asoap closed triangles (LFBY) triangles (NM) closed circles (OKT) circles (LRL) and squares (LX) solidlines represent the model

Table 4 Slopes critical micelle concentration (CMC) maximum surface excess concentration (Γmax) the area occupied by surfactantmolecule (Amin) surface pressure at the CMC (πCMC) effective Gibbs free energy (ΔGo

eff ) and free energy of adsorption (ΔGoads)

Soaps Slopes CMC (mgml) Γmax106(molmminus 2) Amin(A2moleculeminus 1) πCMC(mNmminus 1) ΔGoeff(kJmolminus 1) ΔGo

ads(kJmolminus 1)

LFBY minus280 00659 241 6884 654 minus271 minus3408NM minus235 00710 202 8203 724 minus357 minus3414OKT minus232 00830 199 8343 984 minus492 minus3485LRL minus184 00899 158 1047 1204 minus759 minus3488LX minus182 01110 157 1059 1614 minus1029 minus3622-e error limits of CMC Γmax Amin πCMC ΔGo

eff and ΔGoads are within plusmn 3 plusmn 5 plusmn 4 plusmn 3 plusmn 4 and plusmn 6 respectively

Table 5 -e diameter of zone of inhibition of the pastes againstthree pathogenic bacteria

Soap-e diameter of zone of inhibition in mm

S aureus E coli P vulgarisConcn(microgmicrol) 100 50 25 125 100 50 25 125 100 50 25 125

OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0


Table 5 and the results are evaluated on bar graph (Fig-ure 19) LFBY soap revealed satisfactory bacterial growthinhibition even at the lowest tested concentration relative toother soaps Soap solutions at 100 μgμL concentrationbecame very concentrated and were soon converted tosemisolid form and were unable to show the expected an-tibacterial action All soaps showed their highest action at50 μgμL except LX whose highest activity was shown at25 μgμL From this study looking at the data against Saureus we can say that the use of small amounts of LFBYand LX soaps can kill bacteria among others -e highaction shown by soap at 50 μgμL (and 25 μgμL for LX) canbe argued towards the superior diffusion capacity of soap athigh concentrations -e antibacterial action shown byherbal soaps is less than that of other soaps but not so lowand may still replace chemically manufactured soaps wherebacteria are more likely to become resistant

-e excessive use of antibiotics for the control of in-fections has created some exceptional conditions for de-veloping resistant elements in bacterial populations [51] Inthis era where the strongest of antibiotics are failing to killpathogenic bacteria now becoming superbugs it may not bea big surprise to see the low inactivity of toilet soaps -e so-called continued use of antibacterial soap is itself supportiveof being resistant to bacteria [4] In the present study amongthe bacteria encountered two are seen to be completelyresistant to any soap whereas S aureus is seen to be sus-ceptible Looking at the literature and current tests only afew bacteria are seen to be susceptible to the most common

form of antibacterial agents and are in the same race to beresistant Not only do we take antibiotics or animal feedswith dietary antibiotics (to get healthy and support rapidgrowth) contact with any creature with resistant bacteriacan supply us with those bacteria that eventually turn theharmless bacteria into resistant [52] More surprisingly anyform of the cosmetic product in which manufacturersproudly advertise their product as pathogenic slayer canusually induce and support the resistance in bacteria Eventhough antibacterial soaps can protect patients from thetransfer of opportunistic pathogens prolonged use of an-tiseptic soaps can eliminate both beneficial and harmfulbacteria making the skin more vulnerable to pathogenicmicroorganisms and ultimately antibacterial resistanceRather the use of herbal soaps is supported [4]

4 Conclusion

-e cleaning action of soaps is associated with the surfacetension as well as CMC -e CMC calculated from thesurface tension and conductivity of soaps matched eachother In comparison with other investigated soaps theCMC is more in the LX and has the lowest value of surfacetension Higher CMC and lower surface tension of LX al-ways give more micelles Hence the solution of LX soap isthe effective cleaning solution because of more micellesSimilarly the antibacterial potency of LFBY was foundhigher than other soaps Based on these studies we cansimply take LFBY at the highest rank -e present

S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)

Figure 19 -e antibacterial action of the soaps against the pathogenic bacteria at four different concentrations


investigation reveals solution property study which controlsthe cleansing and removal of dirt and bacteria -e bioactiveingredients present in them provide antibacterial potency tocure various skin problems caused by bacterial pathogens-e antibacterial action of the herbal soap is also satisfactoryand can replace the chemical soaps in needed times -esurface tension data of the complex system give a very goodfitting of the experimental data of surface tension with thehelp of a theoretical model indicating that the presence ofsurface-active agents is more in the soaps Our findings mayserve as a landmark for selecting appropriate soap for thesociety and also motivate to investigate further on the ex-perimental data of surface tension and conductivity forsoaps with more theoretical models

Data Availability

-e graphical data of ingredients of various soaps selectedfor antibacterial assessment supporting this paper have beenuploaded as electronic supplementary material

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Supplementary Materials

S1 Table ingredients of various soaps selected for antibac-terial assessment (Supplementary Materials)

References

[1] O M Ogba P E Asukwo and I B Otu-Bassey ldquoAssessmentof bacterial carriage on the hands of primary school childrenin Calabar municipality Nigeriardquo Biomedical Dermatologyvol 2 no 6 pp 1ndash7 2018

[2] T Yahaya J Okpuzor and E O Oladele ldquoInvestigation oftoxicity of detergentsrdquo Journal of Environmental Science andTechnology vol 4 no 6 pp 638ndash645 2011

[3] S A Kim H Moon K Lee and M S Rhee ldquoBactericidaleffects of triclosan in soap both in vitro and in vivordquo )eJournal of Antimicrobial Chemotherapy vol 70 pp 3345ndash3352 2015

[4] C N Obi ldquoAntibacterial activities of some medicated soapson selected human pathogensrdquo American Journal of Micro-biological Research vol 2 no 6 pp 178ndash181 2014

[5] J L Fuls N D Rodgers G E Fischler et al ldquoAlternative handcontamination technique to compare the activities of anti-microbial and nonantimicrobial soaps under different testconditionsrdquoApplied and Environmental Microbiology vol 74no 12 pp 3739ndash3744 2008

[6] S Riaz A Ahmad and S Hasnain ldquoAntibacterial activity ofsoaps against daily encountered bacteriardquo African Journal OfBiotechnology vol 8 no 8 pp 1431ndash1436 2009

[7] A E Aiello E L Larson and S B Levy ldquoConsumer anti-bacterial soaps effective or just riskyrdquo Clinical InfectiousDiseases vol 45 no 2 pp S137ndashS147 2007

[8] A E Aiello R M Coulborn V Perez and E L LarsonldquoEffect of hand hygiene on infectious disease risk in thecommunity setting a meta-analysisrdquo American Journal ofPublic Health vol 98 no 8 pp 1372ndash1381 2008

[9] B Michaels V Gangar A Schultz et al ldquoWater temperatureas a factor in handwashing efficacyrdquo Food Service Technologyvol 2 no 3 pp 139ndash149 2003

[10] S Bidawid N Malik O Adegbunrin S A Sattar andJ M Farber ldquoNorovirus cross-contamination during foodhandling and interruption of virus transfer by hand antisepsisexperiments with feline calicivirus as a surrogaterdquo Journal ofFood Protection vol 67 no 1 pp 103ndash109 2004

[11] T B Hansen and S Knochel ldquoImage analysis method forevaluation of specific and non-specific hand contaminationrdquoJournal of Applied Microbiology vol 94 no 3 pp 483ndash4942003

[12] N Tabassum and M Hamdani ldquoPlants used to treat skindiseasesrdquo Pharmacognosy Reviews vol 8 no 15 pp 52ndash602014

[13] K Kon and M Rai Antibiotic Resistance Mechanisms andNew Antimicrobial Approaches Sara Tenney Academic PressWashington DC USA 2016

[14] A Chandrasekara and F Shahidi ldquoHerbal beverages bioac-tive compounds and their role in disease risk reduction-areviewrdquo Journal of Traditional and Complementary Medicinevol 8 no 4 pp 451ndash458 2018

[15] O Atolani E T Olabiyi A A Issa et al ldquoGreen synthesis andcharacterisation of natural antiseptic soaps from the oils ofunderutilised tropical seedrdquo Sustainable Chemistry andPharmacy vol 4 pp 32ndash39 2016

[16] A Fathi-Azarbayjani and A Jouyban ldquoSurface tension inhuman pathophysiology and its application as a medicaldiagnostic toolrdquo BioImpacts vol 5 no 1 pp 29ndash44 2015

[17] M O Adebajo M S Akanni and R L Frost ldquoEffect of palmkernel oil extraction method on the electrical conductance ofnigerian traditional soaps in alcoholsrdquo Journal of Surfactantsand Detergents vol 7 no 1 pp 81ndash85 2004

[18] M O Adebajo and M Sola Akanni ldquo-e electrical con-ductance and viscosity of Nigerian traditional soaps in al-coholic mediardquo Colloids and Surfaces A Physicochemical andEngineering Aspects vol 194 no 1ndash3 pp 97ndash110 2001

[19] T P Niraula S K Chatterjee and A Bhattarai ldquoMicellizationof sodium dodecyl sulphate in presence and absence of alkalimetal halides at different temperatures in water and metha-nol-water mixturesrdquo Journal of Molecular Liquids vol 250pp 287ndash294 2018

[20] K M Sachin S A Karpe M Singh and A Bhattarai ldquoSelf-assembly of sodium dodecylsulfate and dodecyl-trimethylammonium bromide mixed surfactants with dyes inaqueous mixturesrdquo Royal Society Open Science vol 6 no 32019

[21] T Mukhim and K Ismail ldquoAggregation counter ion bindingand adsorption behaviors of cetylpyridinium chloride inwaterglycerol media at 25degCrdquo Journal of Surfactants andDetergents vol 15 no 1 pp 47ndash51 2012

[22] P A Koya K -ud-Din and K Ismail ldquoMicellization andthermodynamic parameters of butanediyl-14- bis(te-tradecyldimethylammonium Bromide) gemini surfactant atdifferent temperatures effect of the addition of 2-methox-yethanolrdquo Journal of Solution Chemistry vol 41 no 8pp 1271ndash1281 2012

[23] A Bhattarai K Pathak and B Dev ldquoCationic and anionicsurfactants interaction in water and methanol-water mixedsolvent mediardquo Journal of Molecular Liquids vol 229pp 153ndash160 2017

[24] J M del Rio G Prieto F Sarmiento and V Mosqueraldquo-ermodynamics of micellization of


N-Octyltrimethylammonium bromide in different mediardquoLangmuir vol 11 no 5 pp 1511ndash1514 1995

[25] S Kolay K K Ghosh and P Quagliotto ldquoMicellizationbehavior of [C16-12-C16] 2Br-gemini surfactant in binaryaqueous-solvent mixturesrdquo Colloids and Surfaces A Physi-cochemical and Engineering Aspects vol 348 no 1ndash3pp 234ndash239 2009

[26] P Carpena J Aguiar P Bernaola-Galvan and C CarneroRuiz ldquoProblems associated with the treatment of Con-ductivityminusConcentration data in surfactant solutions simu-lations and experimentsrdquo Langmuir vol 18 no 16pp 6054ndash6058 2002

[27] W H Press S A Teukolsky W Vetterling and B FlanneryNumerical Recipes the Art of Scientific Computing CambridgeUniversity Press Cambridge UK 2007

[28] D Ng S Kundu M Kulkarni and H Liang ldquoRole of sur-factant molecules in post-CMP cleaningrdquo Journal of theElectrochemical Society vol 155 no 2 pp 64ndash68 2008

[29] P Barkvoll ldquo[Should toothpastes foam Sodium lauryl sul-fate--a toothpaste detergent in focus]rdquo Den Norske Tann-laegeforenings Tidende vol 99 no 3 pp 82ndash84 1989

[30] N Dubey ldquoCTAB aggregation in solutions of higher alcoholsthermodynamic and spectroscopic studiesrdquo Journal of Mo-lecular Liquids vol 184 pp 60ndash67 2013

[31] B Kronberg M Costas and R Silveston ldquo-ermodynamicsof the hydrophobic effect in surfactant solutions micellizationand adsorptionrdquo Pure and Applied Chemistry vol 67 no 6pp 897ndash902 1995

[32] K Manna and A K Panda ldquoPhysicochemical studies on theinterfacial and micellization behavior of CTAB in aqueouspolyethylene glycol mediardquo Journal of Surfactants and De-tergents vol 14 no 4 pp 563ndash576 2011

[33] I Mukherjee S P Moulik and A K Rakshit ldquoTensiometricdetermination of Gibbs surface excess and micelle point acritical revisitrdquo Journal of Colloid and Interface Sciencevol 394 no 1 pp 329ndash336 2013

[34] A Pradhan and A Bhattacharyya ldquoShampoos then and now synthetic versus naturalrdquo Journal of Surface Science andTechnology vol 30 no 1-2 pp 59ndash76 2014

[35] S K Shah S K Chatterjee and A Bhattarai ldquo-e effect ofmethanol on the micellar properties of Dodecyl-trimethylammonium bromide (DTAB) in aqueous medium atdifferent temperaturesrdquo Journal of Surfactants and Detergentsvol 19 no 1 pp 201ndash207 2016

[36] M Abdul Rub ldquoAggregation and interfacial phenomenon ofamphiphilic drug under the influence of pharmaceuticalexcipients (greenbiocompatible gemini surfactant)rdquo PLoSOne vol 14 no 2 2019

[37] T Chakraborty I Chakraborty and S Ghosh ldquoSodiumCarboxymethylcellulose-CTAB interaction a detailed ther-modynamic study of Polymer-Surfactant interaction withopposite chargesrdquo Langmuir vol 22 no 24 pp 9905ndash99132006

[38] S S Borse T J Patil and M S Borse ldquoEffect of tuned headpolarity of cetyl trimethyl ammonium bromide on theirphysicochemical propertiesrdquo Tenside Surfactants Detergentsvol 51 no 3 pp 267ndash273 2014

[39] M J Rosen Micelle Formation by Surfactants John Wiley ampSons Hoboken NJ USA 3rd edition 2012

[40] R Patel A B Khan N Dohare M Maroof Ali andH K Rajor ldquoMixed micellization and interfacial properties ofionic liquid-type imidazolium gemini surfactant with am-phiphilic drug amitriptyline hydrochloride and its

thermodynamicsrdquo Journal of Surfactants and Detergentsvol 18 no 5 pp 719ndash728 2015

[41] P S Niranjan and S K Upadhyay ldquoInteraction of poly-acrylamide with conventional anionic and gemini anionicsurfactantsrdquo Journal of Dispersion Science and Technologyvol 32 no 1 pp 109ndash113 2010

[42] U R Dharmawardana S D Christian E E TuckerR W Taylor and J F Scamehorn ldquoA surface tension methodfor determining binding constants for cyclodextrin inclusioncomplexes of ionic surfactantsrdquo Langmuir vol 9 no 9pp 2258ndash2263 1993

[43] V B Fainerman and R Miller ldquoSurface tension isotherms forsurfactant adsorption layers including surface aggregationrdquoLangmuir vol 12 no 25 pp 6011ndash6014 1996

[44] A J Prosser and E I Franses ldquoAdsorption and surfacetension of ionic surfactants at the air-water interface reviewand evaluation of equilibrium modelsrdquo Colloids and SurfacesA Physicochemical and Engineering Aspects vol 178 no 1ndash3pp 1ndash40 2001

[45] A Zdziennicka and B Janczuk ldquoProperties of n-octyl-β-d-glucopyranoside and sodium dodecylsulfate mixedmonolayerat the water-air interfacerdquo Journal of Molecular Liquidsvol 280 pp 259ndash267 2019

[46] C J van Oss Interfacial Forces in Aqueous Media CRC PressNew York NY USA 1994

[47] M R Bresler and J P Hagen ldquoSurfactant adsorption a re-vised physical chemistry labrdquo Journal of Chemical Educationvol 85 no 2 pp 269ndash271 2008

[48] C Zhang T Geng Y Jiang L Zhao H Ju and Y WangldquoImpact of NaCl concentration on equilibrium and dynamicsurface adsorption of cationic surfactants in aqueous solu-tionrdquo Journal of Molecular Liquids vol 238 pp 423ndash4292017

[49] S-Y Lin Y-Y Lin E-M Chen C-T Hsu and C-C KwanldquoA study of the equilibrium surface tension and the criticalmicelle concentration of mixed surfactant solutionsrdquo Lang-muir vol 15 no 13 pp 4370ndash4376 1999

[50] A W Bauer W M M Kirby J C Sherris and M TurckldquoAntibiotic susceptibility testing by a standardized single diskmethodrdquo American Journal of Clinical Pathology vol 45no 4_ts pp 493ndash496 1966

[51] E D Brown and G D Wright ldquoAntibacterial drug discoveryin the resistance erardquo Nature vol 529 no 7586 pp 336ndash3432016

[52] M Barza S Gorbach and S J DeVincent ldquoIntroductionrdquoClinical Infectious Diseases vol 34 no s3 pp S71ndashS72 2002


and also in the year 2015 by Kim et al [3] supported the ideathat antibacterial soaps are not so significant compared tobland soaps Added antibacterial agents have very little timeto show bactericidal action therefore the mechanical aspectof friction is of critical importance In the food and healthcare industries hand-washing practices matter themost-eactivity of soap friction and rinsing are crucial for effectiveantibacterial action [9 10]

Not all bacteria are pathogenic and bactericides are notrequired to be used on daily usable products Antibacterialagents are used in many personal care products such as soapstoothpaste lotions shampoos and other household productssuch as kitchenware clothing furniture and toys Irre-sponsible and abusive use of antimicrobial products is closingthe antibiotic era -ere have been many outbreaks of food-borne diseases and nosocomial infections due to hand con-tamination Ogba et al [1] reported S aureus followed by Ecoli to be the most common isolates on the hands of primaryschool children in Nigeria S aureus and E coli are associatedwith skin infections and food poisoning respectively [11]

Nepal being rich in flora and diversity a lot of amazing lifeforms are planted here Traditionally plant extracts are usedfor many purposes including food preservation flavor en-hancement health improvement and more Plant oils are oldtested and reliable sources for the treatment of various skindiseases and are therefore used in body and skincare products[12] Plant-derived compounds represent an unlimited sourceof safe effective and environmentally friendly antimicrobialsDue to the fascinating antimicrobial effects nontoxic natureand low cost many self-care products like lotions toothpastesoaps etc manufactured here have been enriched with theextracts of natural products [13] -e herbal-based cosmeticsare rich in phytochemicals such as vitamins proteins tanninsterpenoids and other bioactive ingredients that possess an-tioxidant anticancer antimicrobial and other beneficial ac-tions [14] Low toxicity to users and the environment providesa great deal of beauty and medicinal effects [15] Of the fivesoaps selected two (OKT and NM) contained only herbalproducts while LX and LRL contained plant extracts addedwith chemicals

-e present paper aims to evaluate some solution be-havior and in vitro antibacterial efficacy of five toilet soapformulations containing both herbal and chemical-basedingredients -e soap contains surfactants that lower thesurface tension of the solution Lower surface tension hastaken advantage of improved cleansing action by easy dif-fusion on the skin surface [16] With the increase in thepurity of soap there is a profound effect in the electricalconductivity and the presence of impurities can cause someconstraints on the mobility of charge of the soap solution[17 18] Most plant extracts used in herbal-based soaps havemedicinal value In addition the antibacterial efficacy ofnatural herbal extracts in soap was compared and evaluated

2 Experimental

21Materials andMethods All chemicals and reagents usedfor this experiment were of analytical reagent grade Fivesoaps were selected for assessment and were purchased from

the local market of Biratnagar Nepal -ese soap formu-lations are coded as Lux (LX) Lifebuoy (LFBY) Liril (LRL)Okhati (OKT) and Chiuree Neem (NM) -eir ingredientsare listed in Table S1 A Kruss K20S Easy Dyne ForceTensiometer was employed to measure the surface tensionby the ring detachment technique using a platinum ring withthe correction of Harkins and Jordan -e AutorangingConductivityTDS meter TCM 15+ was used to measure thespecific conductance of soap solutions For the antibacterialefficacy assessment the glassware was washed with tripledistilled water and dried in the oven before use Pyrogen-freedistilled water was used for the preparation of solutions andwas made at their four different concentrations such as 1 011 02 1 04 and 1 08 To explore the solution propertiesall soaps solutions were prepared at 02mgmL concentra-tion and kept as stock solutions Further the internal di-lution in tap water was preformed 15 times for all -isstudy carried in tap water was to mimic the daily householdprocedure

22 Antimicrobial Assay -e antibacterial sensitivity of thesoap was studied by the disc diffusion technique -reedifferent bacterial pathogens E coli S Aureus and Pvulgaris which are known to reside on the body surface andgive evidence to cause piles of diseases are deployed in thisevaluation -e bacterial culture was revived by seedingsome well-isolated colonies of pathogens in nutrient brothand incubated for two hours -e sterile Mueller-Hintonagar solution prepared by standard technique was left tocongeal in the sterile Petri plates -e broth of previouslyseeded bacterial culture was spread in the media and thewell-sterilized paper discs of 5mm diameter (Whatman no 1)impregnated with test samples were stuck on the plates Forcomparison of efficacy a disc of antibiotic (amikacin 30 μgdisc) was also installed -e plates were incubated at 37degCfor 24 hours -e antibacterial sensitivity was then assessedby measuring the diameter of the zone of inhibition in mmAll the procedures were repeated three times to reduceerrors

3 Results and Discussion

31 Conductivity and )ermodynamic Properties -e spe-cific conductance of surfactants depends on the nature ofions formed after ionization the nature of the solvent usedthe temperature and the presence of additives like salts [19]-e variation of specific conductivity with the concentrationof soap is well demonstrated in Table 1 and Figure 1 LX hasthe lowest specific conductivity (0404mScm) while LFBY(0454mScm) has the highest -e decrease in specificconductivity with dilution is due to the replacement of ionsby colloidal particles which although conducting has alower equivalent conductivity than the ions from which theyare formed Colloidal particles are thus formed in very lowconcentrations [20] Upon dilution the specific conductivityof all soaps has significantly reduced On the overall view wecan take the specific conductivity of LFBY NM and OKTashigher values and LRL and LX as lower values

















1 0200 0441 0448 0459 0429 04002 0166 0434 0443 0454 0421 03933 0143 0430 0438 0449 0416 03864 0125 0425 0435 0445 0412 03805 0111 0423 0433 0444 0409 03786 0100 0419 0428 0441 0407 03727 0090 0417 0425 0438 0402 03678 0083 0413 0424 0436 0398 03639 0076 0409 0423 0435 0392 035710 0071 0403 0419 0433 0387 035511 0066 0398 0416 0432 0385 035212 0062 0395 0413 0430 0384 034813 0058 0391 0409 0427 0382 034514 0055 0388 0405 0425 0380 034315 0052 0385 0401 0421 0376 034116 005 0382 0399 0418 0375 033917 Tap water 0383

035

040

045

0 005 010 015 020 025[C] (mgmL)

κ (m

Scm

)












0

04

08

12

1 2 3 4 5





S2

S1

Soaps

Slop

e (m

scm

lowast m

Lmiddotm

gndash1)


006

007

008

009

010

011

1 2 3 4 5


Soaps

CMC

(mgmiddot

mLndash1

)


090

095

100

1 2 3 4 5


Soaps

κ oκ

cmc


015

020

025

030

035

040

1 2 3 4 5



Soaps

α



κ( c) A1 minus A2




1 + e minuscoΔc( )1113888 1113889 (3)



approxc


χ2 1113944N

i1Ki minus K

approxi1113858 1113859

2 (4)





01

03

05

07

0 005 010 015 020cmc

[C] (mgml)

κ (m

Scm

)


ndash32

ndash30

ndash28

ndash26

ndash24

1 2 3 4 5Soaps

∆Gdeg m

(kJm

olndash1

)













Γmax minus1

2303nRT

dc

dlog C1113890 1113891

TP

(5)



Amin 1

NΓmax (6)


obtained as


50

55

60

65

70


γ (m

Nm

)







ΔGoads ΔGo

m minusπCMC

Γmax (8)













ΔGoads and ΔG




50

55

60

65

70


LX



Log [C]

γ (m

Nm

)


ndash28

ndash24

ndash20

ndash16

ndash12

1 2 3 4 5


f = ndash352

Soaps

Slop

e (m

Nm

ndash1 lowast

lnm

Lmiddotm

gndash1)


10

11

12

13

1 2 3 4 5


f = 112

Soaps

γ oγ

cmc










1113888 1113889 (9)









adsΔGom)




ndash365

ndash355

ndash345

ndash335

1 2 3 4 5


f = ndash348

Soaps

∆Ga0 ds

(kJmiddotm

olndash1

)


ndash12

ndash10

ndash8

ndash6

ndash4

ndash2

1 2 3 4 5


f = ndash204

Soaps

∆Ge0 ff

(kJmiddotm

olndash1

)


0

5

10

15

20

5 10 15



π cm

cAm

in

πcmc






I [Soap]total


1 + 131I05( )+ 0049I

(10)





δc

1113936Ni1 cexpi


N

1113971

(12)


Γmax




10

11

12

13

14

1 2 3 4 5


Soaps

∆G0 ad

s∆G

m0


om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5


Soaps

CMC

pC20


06

07

08

09

10

0 01 02 03 04


Soaps

ΓΓ m

ax










(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References








































































1 0200 0441 0448 0459 0429 04002 0166 0434 0443 0454 0421 03933 0143 0430 0438 0449 0416 03864 0125 0425 0435 0445 0412 03805 0111 0423 0433 0444 0409 03786 0100 0419 0428 0441 0407 03727 0090 0417 0425 0438 0402 03678 0083 0413 0424 0436 0398 03639 0076 0409 0423 0435 0392 035710 0071 0403 0419 0433 0387 035511 0066 0398 0416 0432 0385 035212 0062 0395 0413 0430 0384 034813 0058 0391 0409 0427 0382 034514 0055 0388 0405 0425 0380 034315 0052 0385 0401 0421 0376 034116 005 0382 0399 0418 0375 033917 Tap water 0383

035

040

045

0 005 010 015 020 025[C] (mgmL)

κ (m

Scm

)












0

04

08

12

1 2 3 4 5





S2

S1

Soaps

Slop

e (m

scm

lowast m

Lmiddotm

gndash1)


006

007

008

009

010

011

1 2 3 4 5


Soaps

CMC

(mgmiddot

mLndash1

)


090

095

100

1 2 3 4 5


Soaps

κ oκ

cmc


015

020

025

030

035

040

1 2 3 4 5



Soaps

α



κ( c) A1 minus A2




1 + e minuscoΔc( )1113888 1113889 (3)



approxc


χ2 1113944N

i1Ki minus K

approxi1113858 1113859

2 (4)





01

03

05

07

0 005 010 015 020cmc

[C] (mgml)

κ (m

Scm

)


ndash32

ndash30

ndash28

ndash26

ndash24

1 2 3 4 5Soaps

∆Gdeg m

(kJm

olndash1

)













Γmax minus1

2303nRT

dc

dlog C1113890 1113891

TP

(5)



Amin 1

NΓmax (6)


obtained as


50

55

60

65

70


γ (m

Nm

)







ΔGoads ΔGo

m minusπCMC

Γmax (8)













ΔGoads and ΔG




50

55

60

65

70


LX



Log [C]

γ (m

Nm

)


ndash28

ndash24

ndash20

ndash16

ndash12

1 2 3 4 5


f = ndash352

Soaps

Slop

e (m

Nm

ndash1 lowast

lnm

Lmiddotm

gndash1)


10

11

12

13

1 2 3 4 5


f = 112

Soaps

γ oγ

cmc










1113888 1113889 (9)









adsΔGom)




ndash365

ndash355

ndash345

ndash335

1 2 3 4 5


f = ndash348

Soaps

∆Ga0 ds

(kJmiddotm

olndash1

)


ndash12

ndash10

ndash8

ndash6

ndash4

ndash2

1 2 3 4 5


f = ndash204

Soaps

∆Ge0 ff

(kJmiddotm

olndash1

)


0

5

10

15

20

5 10 15



π cm

cAm

in

πcmc






I [Soap]total


1 + 131I05( )+ 0049I

(10)





δc

1113936Ni1 cexpi


N

1113971

(12)


Γmax




10

11

12

13

14

1 2 3 4 5


Soaps

∆G0 ad

s∆G

m0


om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5


Soaps

CMC

pC20


06

07

08

09

10

0 01 02 03 04


Soaps

ΓΓ m

ax










(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References


































































0

04

08

12

1 2 3 4 5





S2

S1

Soaps

Slop

e (m

scm

lowast m

Lmiddotm

gndash1)


006

007

008

009

010

011

1 2 3 4 5


Soaps

CMC

(mgmiddot

mLndash1

)


090

095

100

1 2 3 4 5


Soaps

κ oκ

cmc


015

020

025

030

035

040

1 2 3 4 5



Soaps

α



κ( c) A1 minus A2




1 + e minuscoΔc( )1113888 1113889 (3)



approxc


χ2 1113944N

i1Ki minus K

approxi1113858 1113859

2 (4)





01

03

05

07

0 005 010 015 020cmc

[C] (mgml)

κ (m

Scm

)


ndash32

ndash30

ndash28

ndash26

ndash24

1 2 3 4 5Soaps

∆Gdeg m

(kJm

olndash1

)













Γmax minus1

2303nRT

dc

dlog C1113890 1113891

TP

(5)



Amin 1

NΓmax (6)


obtained as


50

55

60

65

70


γ (m

Nm

)







ΔGoads ΔGo

m minusπCMC

Γmax (8)













ΔGoads and ΔG




50

55

60

65

70


LX



Log [C]

γ (m

Nm

)


ndash28

ndash24

ndash20

ndash16

ndash12

1 2 3 4 5


f = ndash352

Soaps

Slop

e (m

Nm

ndash1 lowast

lnm

Lmiddotm

gndash1)


10

11

12

13

1 2 3 4 5


f = 112

Soaps

γ oγ

cmc










1113888 1113889 (9)









adsΔGom)




ndash365

ndash355

ndash345

ndash335

1 2 3 4 5


f = ndash348

Soaps

∆Ga0 ds

(kJmiddotm

olndash1

)


ndash12

ndash10

ndash8

ndash6

ndash4

ndash2

1 2 3 4 5


f = ndash204

Soaps

∆Ge0 ff

(kJmiddotm

olndash1

)


0

5

10

15

20

5 10 15



π cm

cAm

in

πcmc






I [Soap]total


1 + 131I05( )+ 0049I

(10)





δc

1113936Ni1 cexpi


N

1113971

(12)


Γmax




10

11

12

13

14

1 2 3 4 5


Soaps

∆G0 ad

s∆G

m0


om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5


Soaps

CMC

pC20


06

07

08

09

10

0 01 02 03 04


Soaps

ΓΓ m

ax










(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References

























































κ( c) A1 minus A2




1 + e minuscoΔc( )1113888 1113889 (3)



approxc


χ2 1113944N

i1Ki minus K

approxi1113858 1113859

2 (4)





01

03

05

07

0 005 010 015 020cmc

[C] (mgml)

κ (m

Scm

)


ndash32

ndash30

ndash28

ndash26

ndash24

1 2 3 4 5Soaps

∆Gdeg m

(kJm

olndash1

)













Γmax minus1

2303nRT

dc

dlog C1113890 1113891

TP

(5)



Amin 1

NΓmax (6)


obtained as


50

55

60

65

70


γ (m

Nm

)







ΔGoads ΔGo

m minusπCMC

Γmax (8)













ΔGoads and ΔG




50

55

60

65

70


LX



Log [C]

γ (m

Nm

)


ndash28

ndash24

ndash20

ndash16

ndash12

1 2 3 4 5


f = ndash352

Soaps

Slop

e (m

Nm

ndash1 lowast

lnm

Lmiddotm

gndash1)


10

11

12

13

1 2 3 4 5


f = 112

Soaps

γ oγ

cmc










1113888 1113889 (9)









adsΔGom)




ndash365

ndash355

ndash345

ndash335

1 2 3 4 5


f = ndash348

Soaps

∆Ga0 ds

(kJmiddotm

olndash1

)


ndash12

ndash10

ndash8

ndash6

ndash4

ndash2

1 2 3 4 5


f = ndash204

Soaps

∆Ge0 ff

(kJmiddotm

olndash1

)


0

5

10

15

20

5 10 15



π cm

cAm

in

πcmc






I [Soap]total


1 + 131I05( )+ 0049I

(10)





δc

1113936Ni1 cexpi


N

1113971

(12)


Γmax




10

11

12

13

14

1 2 3 4 5


Soaps

∆G0 ad

s∆G

m0


om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5


Soaps

CMC

pC20


06

07

08

09

10

0 01 02 03 04


Soaps

ΓΓ m

ax










(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References


































































Γmax minus1

2303nRT

dc

dlog C1113890 1113891

TP

(5)



Amin 1

NΓmax (6)


obtained as


50

55

60

65

70


γ (m

Nm

)







ΔGoads ΔGo

m minusπCMC

Γmax (8)













ΔGoads and ΔG




50

55

60

65

70


LX



Log [C]

γ (m

Nm

)


ndash28

ndash24

ndash20

ndash16

ndash12

1 2 3 4 5


f = ndash352

Soaps

Slop

e (m

Nm

ndash1 lowast

lnm

Lmiddotm

gndash1)


10

11

12

13

1 2 3 4 5


f = 112

Soaps

γ oγ

cmc










1113888 1113889 (9)









adsΔGom)




ndash365

ndash355

ndash345

ndash335

1 2 3 4 5


f = ndash348

Soaps

∆Ga0 ds

(kJmiddotm

olndash1

)


ndash12

ndash10

ndash8

ndash6

ndash4

ndash2

1 2 3 4 5


f = ndash204

Soaps

∆Ge0 ff

(kJmiddotm

olndash1

)


0

5

10

15

20

5 10 15



π cm

cAm

in

πcmc






I [Soap]total


1 + 131I05( )+ 0049I

(10)





δc

1113936Ni1 cexpi


N

1113971

(12)


Γmax




10

11

12

13

14

1 2 3 4 5


Soaps

∆G0 ad

s∆G

m0


om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5


Soaps

CMC

pC20


06

07

08

09

10

0 01 02 03 04


Soaps

ΓΓ m

ax










(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References



























































ΔGoads ΔGo

m minusπCMC

Γmax (8)













ΔGoads and ΔG




50

55

60

65

70


LX



Log [C]

γ (m

Nm

)


ndash28

ndash24

ndash20

ndash16

ndash12

1 2 3 4 5


f = ndash352

Soaps

Slop

e (m

Nm

ndash1 lowast

lnm

Lmiddotm

gndash1)


10

11

12

13

1 2 3 4 5


f = 112

Soaps

γ oγ

cmc










1113888 1113889 (9)









adsΔGom)




ndash365

ndash355

ndash345

ndash335

1 2 3 4 5


f = ndash348

Soaps

∆Ga0 ds

(kJmiddotm

olndash1

)


ndash12

ndash10

ndash8

ndash6

ndash4

ndash2

1 2 3 4 5


f = ndash204

Soaps

∆Ge0 ff

(kJmiddotm

olndash1

)


0

5

10

15

20

5 10 15



π cm

cAm

in

πcmc






I [Soap]total


1 + 131I05( )+ 0049I

(10)





δc

1113936Ni1 cexpi


N

1113971

(12)


Γmax




10

11

12

13

14

1 2 3 4 5


Soaps

∆G0 ad

s∆G

m0


om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5


Soaps

CMC

pC20


06

07

08

09

10

0 01 02 03 04


Soaps

ΓΓ m

ax










(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References
































































1113888 1113889 (9)









adsΔGom)




ndash365

ndash355

ndash345

ndash335

1 2 3 4 5


f = ndash348

Soaps

∆Ga0 ds

(kJmiddotm

olndash1

)


ndash12

ndash10

ndash8

ndash6

ndash4

ndash2

1 2 3 4 5


f = ndash204

Soaps

∆Ge0 ff

(kJmiddotm

olndash1

)


0

5

10

15

20

5 10 15



π cm

cAm

in

πcmc






I [Soap]total


1 + 131I05( )+ 0049I

(10)





δc

1113936Ni1 cexpi


N

1113971

(12)


Γmax




10

11

12

13

14

1 2 3 4 5


Soaps

∆G0 ad

s∆G

m0


om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5


Soaps

CMC

pC20


06

07

08

09

10

0 01 02 03 04


Soaps

ΓΓ m

ax










(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References




























































I [Soap]total


1 + 131I05( )+ 0049I

(10)





δc

1113936Ni1 cexpi


N

1113971

(12)


Γmax




10

11

12

13

14

1 2 3 4 5


Soaps

∆G0 ad

s∆G

m0


om) with soaps

0090

0105

0120

0135

0150

0165

1 2 3 4 5


Soaps

CMC

pC20


06

07

08

09

10

0 01 02 03 04


Soaps

ΓΓ m

ax










(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References
































































(15)





40

50

60

70

00015 00030 00045 00060 00075 00090






aSOAP

γ





ads(kJmolminus 1)






OKT 14 15 13 0 0 0 0 0 0 0 0 0NM 13 19 18 11 0 0 0 0 0 0 0 0LFBY 13 25 20 20 0 0 0 0 8 0 0 0LX 13 21 25 15 0 0 0 0 0 0 0 0LRL 13 23 17 8 0 0 0 0 0 0 0 0





4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References




























































4 Conclusion


S aureus

Ecoli

P vulgaris

0

5

10

15

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 100microgmicroL

(a)

S aureus

Ecoli

P vulgaris

05

10152025

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 50microgmicroL

(b)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

25

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 25microgmicroL

(c)

S aureus

Ecoli

P vulgaris

0

5

10

15

20

OKT NM LFBY LX LRL

Dia

met

er o

f zon

e of

inhi

bitio

n in

mm

at 125microgmicroL

(d)




Data Availability






References


























































Data Availability






References

























































Conductivity,SurfaceTension,andComparativeAntibacterial ...

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