AluminuminEffluentsandSludgesfromthePreliminary...

Research ArticleAluminum in Effluents and Sludges from the PreliminaryCoagulation in Dairy Factory Aerated Balancing Tanks AnAnalytical and Sorption Study

Michał Sadowski Piotr Anielak and Wojciech M Wolf

Institute of General and Ecological Chemistry Faculty of Chemistry Lodz University of Technology 116 Zeromskiego Street90-924 Lodz Poland

Correspondence should be addressed to Michał Sadowski michalsadowskieduplodzpl

Received 15 April 2018 Revised 1 November 2018 Accepted 8 November 2018 Published 4 December 2018

Academic Editor Hassan Arida

Copyright copy 2018 Michał Sadowski et al is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

e coagulation process is used as the first step for the chemical treatment of liquid waste Resulting wet sludge is treated withcoagulants or polyelectrolytes to improve dewatering characteristics of its so-called conditioning e coagulants such as alu-minum sulphate or polyaluminum chloride (Al2Cln(OH)6minusn) are widely used for dairy wastewater treatment systems epretreatment dairy sludge can be applied in agriculture as fertilizer containing valuable nutrients Hence a simple cost effectiveand rapidmethod for the determination of aluminum content in the sludge is essential for calculation of the appropriate coagulantdose at the sludge pretreatment process In this paper either colorimetric or atomic absorption spectrometric methods as appliedfor the determination of aluminum concentration in the dairy wastewater are compared For colorimetric method the optimumexperimental conditions such as pH reaction time and concentration of other ions in the sample were determined e sorptionisotherms of aluminum on the activated sludge were determined for diverse aluminum species

1 Introduction

Dairy manufacturing has become one of the fastest growingand most profitable sectors of food industry in PolandDomestic milk production approached 129mln liters in2015 [1] Unfortunately dairy farms and factories are alsoone of the largest sewage producers in Poland Assumingthat each 1m3 of processed milk provides almost 32m3 ofwastewater it can be extrapolated that total amount of dairysewage in 2015 approached 413mln liters [2]

e coagulation process is widely used as the first step forchemical treatment of liquid waste Resulting wet sludge istreated with coagulants or polyelectrolytes in a processknown as conditioning to improve its dewatering charac-teristics e coagulants such as aluminum sulphate orpolyaluminum chloride are commonly used for dairywastewater treatment systems to enhance sedimentation rateof organic matter e European Union promotes usage ofthe sewage sludge in agriculture [3] e utilization by the

thermal treatment ie pyrolysis gasification or combustionis also supported [4] is also concerns aluminum ionsbecause in relatively low concentrations they may becometoxic either to plants or to the aquatic environment Alu-minum and its compounds can interact with metals andnonmetals leading to changes in the biological availability ofessential elements which are necessary for the properfunctioning of living organisms Dewatered dairy sludge isan important source of inorganic and organic nutrients andmay be used in agriculture for the soil fertilization andimprovement erefore a simple cost effective and rapidmethod for the determination of aluminum content in thesludge is essential for calculation of the appropriate co-agulant dose at the sludge pretreatment process It may alsobe useful for controlling the final aluminum level just beforethe soil fertilization

For many years the basic analytical method being usedto determine the concentration of aluminum in industrialwastewater was the colorimetric analysis It is based on the

HindawiJournal of ChemistryVolume 2018 Article ID 3150363 8 pageshttpsdoiorg10115520183150363

well-recognized ability of aluminum to form colourfulcomplexes with organic compounds such as eriochromecyanine R (3Prime-sulfo-33prime-dimethyl-4-hydroxyfuchson-55prime-dicarboxylic (ECR)) (Figure 1) catechol violet [5] or alu-minon [6]

Nowadays modern analytical techniques such as atomicabsorption spectrometry (AAS) and inductively coupledplasma spectrometry (ICP) have challenged classic colori-metric analysis Both methods are quite expensive and re-quire considerable expertise In this study aluminumconcentration in wastewater has been determined bymodied spectrophotometric method which is characterizedby good precision high reproducibility low cost andsimplicity Flame and graphite furnace atomic absorptionspectrometries [7] were used as reference methodologies

Aluminum is an amphoteric element with the lowestsolubility at neutral pH when it precipitates as aluminumhydroxide Al(OH)3 Its solubility increases in either acidic oralkaline solutions Aluminum can form complexes with ECRgiving stable compounds such as Al-ECR3 or Al-ECR2OH inthe range of pH 5 to 6 [8] (Figure 2) erefore during theanalysis it is necessary to take into account the impact ofsolution pH on the structure of aluminum-ECR complexes

An important issue aecting the metalsrsquo determinationin complex samples is the interfering eect of matrixcomponents especially in highly saline samples includingseawaters dialysis solutions or mineralisates is matrixeect can be corrected by the careful sample mineralizationand the standard addition calibration method e pHoptimization for the signal to noise enhancement is man-datory [9]

2 Experimental

21 e Dairy Sewage Materials e examined sewage wasgenerated in the production of cottage cheese in the dairyfactory located in Lodz region Postproduction sewage isdrained to the factory sewage pretreatment plant whichconsists of three aerated balancing tanks followed by thesedimentation tank Aluminum coagulants were added tothe former to keep the pH at the 65 level Wastewater wasdischarged into the municipal sewage system after the four-day treatment time Samples were collected from balancingtanks in a two-week period over the whole 2017 year

211 e pH Optimization e experimental studies werecarried out to get the information about impact of acetatebuer concentration and pH value on spectrophotometricECR method for determination of aluminum content indairy sewage samples e correct solution pH was main-tained by using acetate buer e various concentrations ofacetate buer as well as dierent ratios of buer componentswere investigated e buer was prepared by mixingCH3COONamiddot3H2O with CH3COOH (Chempur Piekary SlPoland)

212 Measurements of the UV-Vis Spectra Maximum ab-sorbance wavelength for both eriochrome cyanine R and

complex of Al-ECR was determined e ECR was suppliedby POCH (Gliwice Poland)e spectra were measured on aUV-Vis spectrophotometer (2041-PC Shimadzu Japan)e reference sample was deionized water and the analyzedsamples contained aluminum in the form of eitherKAl(SO4)212H2O (Chempur) or polyaluminum chloride(Kemira PAX) at concentration of 74middot10minus2mMe sampleswere prepared in accordance with the procedure for de-termining the aluminum content in environmental samplesas described in the Polish Standard [10]

213 Mineralization of the Samples Due to the highcontent of organic compounds in the samples the driedsamples of the dairy sludge were mineralized before thealuminum content was determined e each sludgemineralization was made by closed microwave reactionsystem Multiwave 300 (Anton Paar USA) e averagemass of the tested samples was about 01 g e mixture of6 1mL (866mM HNO3 (Chempur) and 117mM HCl(Chempur)) was applied In the next step the mineralisateswere lled up to 100ml with deionized water e sameacid mixture was also added in the course of preparing thecalibration curves for mineralisates e oxidative eect ofHNO3HCl mixture on absorbance of emergent complexAl-ECR3 was also investigated e acid mixture concen-tration used for calibration curves was gradually increasedfrom 01mM to 10mM e constant aluminum and theECR doses (74middot10minus2 and 373middot10minus2 mM respectively) wereapplied

214 Measurements of the Absorption Colorimetric Complexe absorption intensity of the tested aluminum complexwas measured using Spekol 11 colorimeter (Carl-Zeiss Jena

CH3

O

O

HOO

O

OSO

OO

Na

NaNa

CH3

Figure 1 e chemical structure of eriochrome cyanine R (ECR)

ML3

MLH ML3H

ML2OH

0

20

40

60

80

100

20 25 30 35 40 45 50 55 60 65 70 75 80

Mol

ar p

erce

ntag

e of

com

plex

Sample pH value

Figure 2 e types of complexes Al3+-ECR depending on solutionpH μ 01M KNO3 [8]

2 Journal of Chemistry

Germany) Samples for analysis were prepared in accor-dance with the procedure described in Polish Standards [10]taking into account the differences in concentrations ofacetate buffer dependent on type of sample physical state andorganic matter content When determining the Al con-centration in samples of nonmineralized supernatant liquidsulfuric acid was used (001M) while in other samples it wasused a mixture of nitric acid and hydrochloric acid (005M)All pH value measurements were made by a pH meter(Model N-517 Mera-Elwro Poland)

In colorimetric method it is necessary to prepare cali-bration curves before every analysis It is the simplest way toreduce influence of random errors on the analysis Foraluminum determination in concentration range of001ndash050mgmiddotLminus1 was prepared a calibration curve followingthe procedure as described in Hermanowicz et al [11] ecalibration solutions were obtained by dissolvingKAl(SO4)2middot12H2O (Chempur) in double distilled water eabsorbance was measured at 535 nm against a blank solutioncontaining only the reagents used in analysis

e formation of the Al(ECR)3 complex takes place inpH range 50ndash60 e pH value of supernatant liquor wasadjusted to the optimum range by adding sulfuric acid(001M) according to the Polish Standard [10] and Her-manowicz et al [11] e ECR concentration in all studieswas kept constant at 373middot10minus2mM [12]

Based on earlier studies on the Al-ECR complex stability[6] as well as our own analyses it was concluded that themost intensive signal appeared in 10min after adding theeriochrome reagent is time was applied to all investigatedsamples

215 +e Filtered Supernatant Liquid In the first stepdairy slurry was homogenized by magnetic stirrer andthen was filtered through the medium filter paper ealuminum residual content in filtrate was determined bygraphite furnace atomic adsorption spectrometry(GFAAS) e aluminum concentration never exceededthe value of 0015mgmiddotLminus1 e difference between theblank sample containing the supernatant and the blanksample for deionized water was subtracted from analysisdata

22 Atomic Absorption Spectrometry e basic methods todetermining aluminum content in sewage sludge are in-strumental techniques mainly based on atomic absorptionspectrometry e Polish Standard [7] recommends usingthe flame atomic absorption spectrometry (FAAS) for de-termining the concentration of aluminum in the range from5mgmiddotLminus1 to 100mgmiddotLminus1 e content of aluminum was an-alyzed by ermo Elemental SOLAAR S2 Flame AASpectrometer (ermo Scientific Waltham USA) Studieshave shown that at concentrations above 5mgmiddotLminus1 thismethod is completely satisfactory At low concentrationsless than 4mgmiddotLminus1 the accuracy of the assay is unsuitableand SD value reaches exceeding 5 e graphite furnaceatomic absorption spectrometry (GFAAS) is recommendedfor small or trace aluminum contents from 001 to

01mgmiddotLminus1 [7] GFAAS spectrometer Sensa AA (GBC Sci-entific Equipment Braeside VIC Australia) was appliede introduced division is applied to analyze both sewagesludge samples and supernatant liquid

Graphite furnace atomic absorption spectrometry is amethod based on atomization of aluminum as a result ofheating the graphite tube e nitrous oxide-acetylene flameis a oxidantfuel combination which has a maximumtemperature of about 2900degC [13] e liquid aluminumsample was heated stepwise (up to 2500degC for 50 seconds) toevaporate [14] Aluminum determination was made at anexcitation wavelength of 30935 nm at a slit width of 05 nm[7] All atomic absorption measurements were made using asingle-element aluminum hollow-cathode lamp (PhotronNarre Warren Australia) e GFAAS calibration curveswere prepared by adequate dilutions of a 1000mgmiddotLminus1 alu-minum standard solution for ASS (Merck Germany) inrange 001 005 010mgmiddotLminus1

e main disadvantage in GFAAS aluminum analysis ismatrix interference and the formation of refractory carbides[15] From among three chemical modifiers ie phosphoricacid (Chempur) [16] Mg(NO3)2 (Merck) [17] andPd(NO3)2 (Merck) the last was chosen e mixture ofPd(NO3)2Mg(NO3)2 as a chemical modifier is recom-mended too [18 19] Pd(NO3)2 can be used to stabilise Alions at higher pyrolysis temperature [20] Palladium mod-ifier gives correct results of aluminum content when thesamples have low silica content [21] e interference ofeasily decomposing chlorides was eliminated by a nitric acidacidification of the sample [22]

3 Results and Discussion

31 +e Colorimetric Method Maximum absorbancewavelength was determined for both eriochrome cyanine Rand Al-ECR complex As shown in Figure 3 the absorptionspectrum of ECR has maximum absorbance at wavelength of440 nm and for Al-ECR complex the absorption peak isshifted to longer wavelengths (535 nm)

32 +e Buffer Capacity of the System Following Herma-nowicz et al [11] the acetate buffer at concentration 020Mwas used to obtain pH 615 but the standard method forspectrophotometric determination of aluminum recom-mends the usage of stronger acetate buffer of 046M whichgives pH 635 [10] is issue is of particular importancewhen applied strongly acidic mixtures in the microwavemineralization when the capacity of the weaker acetatebuffer was practically exhausted (Figure 4)

e acid concentration above 6mM leads to de-composition of the chromogenic reagent if a weaker acetatebuffer was used e stronger buffer solution of 046M wassufficient to neutralize the damaging acid impact

e solutionsrsquo pH values in this analysis were withinrange from 67 to 25 and themaximum solution absorbanceoccurred at pH of 61 when the most stable complexesbetween aluminum and triple molecules ECR-like ligandsare formed [8] e absorbance decreases with increase of

Journal of Chemistry 3

the hydrogen ion concentration and nally the oxidation ofECR occurs at the pH value 35ndash37 (Figure 5)

Figure 6 shows the inumluence of acetate buer concen-tration on the absorbance of the Al(ECR)3 complex econcentration of a HCl and HNO3 mixture was xed at174mM for all analysis in this experiment

e buer at concentration of 020M gives a higherabsorbance values despite lower pH of the sample ie 517plusmn 003 e stronger buer (046M) allows to obtain pHvalue of 555 plusmn 005 However its greater ionic strengthdisturbs the ECR complex formation and in eect reducesthe sensitivity of absorbance measurements

As shown in Figure 7 the buer concentration has animpact on the absorbance value but has no inumluence on theoptimum wavelength for particular measurement e redline corresponds to the high pH and high concentration ofthe acetate buer (046M) while the blue and green linesrepresent absorbance obtained with the 020M buer

33 e Organic Matter in ECR Colorimetric Methodree calibration curves were prepared by diluting thestandard aluminum solution in the form KAl(SO4)2middotH2Oe rst curve (series 1) was made according to the PolishStandard [10] in a range of aluminum concentrations from007mgmiddotLminus1 to 049mgmiddotLminus1 e second curve (series 2) wasprepared in a similar way but instead deionized water 20mlof supernatant liquid was added e third curve (series 3)was based on the supernatant liquid and treated by min-eralization according to the Polish Standard [10] where

oxidation acids were evaporated at the end e pH ofsamples was adjusted to value 63 by addition of acetatebuer

Figure 8 shows dierences between the slopes of cali-bration curves In real samples the organic matrix com-ponents interact with aluminum e compounds ofaluminum and organic matter have often greater stabilitythan the complex of aluminum and the eriochrome cyanineR [14] Additionally there was the intensication of in-teractions of dierent ions which appeared in samples as aconsequence of mineralization process As a result there is adecrease in the signal of Al(ECR)3 complex e absorbancesignals of curve 2 and 3 were lower against the standardcalibration curve 1

001020304050607

300 400 500 600 700

Abso

rptio

n (mdash

)

Wavelength (nm)

Figure 3 Spectra of eriochrome cyanine R (blue) and Al-ECRcomplexes (green) against distilled water with the following con-ditions pH 520 acetate buer 02M Al3+ 74middot10minus2mM

ndash02ndash01

00102030405

0 1 2 3 4 5 6 7 8 9 10

Abso

rban

ce (mdash

)

HNO3HCl (mM)

Buffer 1 (020M)Buffer 2 (046M)

Figure 4 e eect of acid concentration on absorbance

ndash02ndash01

00102030405

2531374349556167

Abso

rban

ce (mdash

)

pH value (mdash)

Figure 5 e pH eect on Al-ECR3 signal intensity acetate buer(02M Al3+ (74middot10minus2mM))

y = 12636x

y = 09699x

0

02

04

06

0 01 02 03 04 05

Abso

rban

ce (mdash

)

Al concentration (mg Lndash1)

Buffer 1 (020M)Buffer 2 (046 M)

Figure 6 Inumluence of acetate buer concentrations on absorbance

0005

01015

02025

03035

500 520 540 560 580 600

Abso

rptio

n (mdash

)

Wavelength (nm)

Figure 7 Spectra of Al-ECR complexes at various concentrationsof acetate buer and pH in relation to blank probe blue 52orange 55 green 49 Al3+ (74middot10minus2mM)


34 e Graphite Furnace Atomic Adsorption SpectroscopyDetermination of aluminum content in samples by GFAASbrings a lot of dilaquoculties in implementing the analysis erst experimental problem is the purity of reagents used tomeasurements Only high analytical grade reagents could beapplied to avoid interferences of dierent ions and inumluenceof aluminum contained in that Many analyses have shownthat this problem occurs for the rst step when calibrationcurve was prepared

e quality and the lifetime of graphite tube are par-ticularly important because many analyses on the sametube lead to irremediable adsorption of trace contentaluminum on the tube surface e optimum number ofmeasurement with a single tube is dilaquocult to estimatebecause it depends on the aluminum concentration inmeasured samples [23]

e next problem is a prerequisite for homogeneity ofthe sample [24] GFAAS is a very sensitive method whereumluctuations in local concentrations of aluminum resultfrom the aluminum binding by hydrophobic organiccompounds such as ligands It leads to rejection of ana-lytical results

35 Comparison of GFAAS and ECR Colorimetric Methode analyzed samples both supernatant and solid sludgehave a complex chemical composition and substantialmatrix eects are very likely e interfering eect of matrixcomponents can be minimalized by the samplesrsquo mineral-ization and using standard addition calibration method Forthis reason the aluminum determination by atomic ab-sorption spectrometry and by colorimetric method withECR ligands was evaluated

Results of aluminum concentration analyses in samplesof mineralized supernatant for both measurement methodswere compared A calibration curve was prepared with theaddition of 20mL of mineralized supernatant analogouslyto the previously described procedure (p 313) A cali-bration curve for GFAAS was also prepared according tothe Polish Standard [7] for the aluminum standard and formineralisate with the addition of standard at 5-fold dilutionof the samples so that the aluminum concentrationsranged from 005mgmiddotLminus1 to 05mgmiddotLminus1 For preparedsamples a 3-fold measurement was made e obtained

results indicate that deviations from the actual signal valueincrease with the increase of the concentration of matrixcomponents e main reason of the increase in the de-viation from the true absorbance value is the increase of theionic strength of solutions

Figure 9 shows the dierence between the reading value(rhombus red dashed line for GFAAS method and squareblue dashed line for colorimetric complex method) and thereal the aluminum concentration in the studied supernatantliquid (green line) e red and yellow columns (fromGFAAS and Al(ECR)3 respectively) in the bottom showsdeviation from the real aluminum content in percentstandard deviation scale e colorimetric method read-outresults are lower in the whole measuring range compared toreal contents

It should be noted that similar results can be obtained forsamples of mineralized supernatant liquid when the con-centration of Al+3 ions is up to 025mgmiddotLminus1 Based on theanalyses it can be concluded that the GFAAS method betterdetermines the actual content in the samples than theAl(ECR)3 method

36 Adsorption Study Experiments were conducted to de-termine the adsorptive capacity of activated sludge towardsaluminum e sewage sludge was prepared by washingseveral times with deionized water to remove the impuritiesand then ltration through standard lter paperse sludgewas mixed with water by the magnetic stirrere aluminumconcentration in ltrate samples for each batch neverexceeded 15 microgmiddotLminus1 and they could be treated as a blanksample Such low aluminum concentrations could be de-termined only by GFAAS

About 01 g of activated sludge (dry weight) was shakenwith 100mL of aluminum solutions of various concentra-tions in the range 10ndash170mgmiddotLminus1 for a contact time of 5 hAluminum was used in the form of various chemicalcompounds listed below e solutions were ltered and thesupernatants were analyzed for Al residues using FAASmethode adsorption elaquociency was calculated by dividingthe amount of adsorbed metal by the mass of activatedsludge

Figure 10 indicates high adsorption of aluminum in theform of sulphate at a pH of about 45 (yellow line) Aneutralization of the solution by sodium hydroxide to pHabout 70 leads to the formation of insoluble aluminumhydroxide Al(OH)3 and it causes almost total metal ad-sorption (blue line) e analyzed samples measured byGFAAS method gives aluminum concentration read-outsbelow 005mgmiddotLminus1 e same samples analyzed by FAASgive unreal aluminum content in level exceeding04mgmiddotLminus1 e umlame atomic absorption spectrometrygives reproducible results for the aluminum concentrationabove 5mgmiddotLminus1

e use of acidic coagulants type PAX 25 (green line)and PAX 19H (purple line) shows lower adsorption be-cause pH value of tested samples is low in the range of 35 plusmn03 e aluminum adsorption for PAX 19H is particularlylow and does not exceed 10mgmiddotLminus1 It showed also worst

0010203040506

0 01 02 03 04 05

Abso

rban

ce (mdash

)

e aluminum concentration (mg Lndash1)

Series 1Series 2

Figure 8 Dependence between absorbance and aluminumconcentration


sludge sedimentation probably due to higher solution acidity[25] e samples with the addition of the alkaline coagulantSAX 18 (red line) showed pH value from 65 to 95 For SAX18 aluminum adsorption elaquociency incipiently was better butin nal coagulants doses were much worse in comparisonwith PAX 25 (reaction sample close to 35)

It should be noted that both aluminum sulphate andPAX 25 at a dose exceeding 10mgmiddotLminus1 aluminum show anacidic pH of the solution of similar value en acidic formsof aluminum Al(OH2)6+3 and AlOH(OH2)5+2 are formed[26] So such large dierences in the adsorption of alu-minum by sludge must therefore be caused by dierences inthe structure of aluminum compounds used ie poly-aluminum chloride In the case of basic SAX 18 the pH valueof the solution increases leading to the formation of solublealuminum forms such as Al(OH)2+ Hence the conclusion isthat ionic reactions have a signicant role in the sorption ofaluminum by the activated sludge during the coagulationprocess

e sorption of aluminum dependent on dosed coagulanttype is an important but not the only factor aecting theelaquociency of sewage sludge treatment It should also take intoaccount such measures of treated wastewater as TOC TNNTU size and viscosity of the resulting aggregates of sludge

4 Conclusions

Wastewater produced in dairy plants is commonly treatedwith aluminum sulphate or polyaluminum chloride co-agulants ey enhance sedimentation rate of organic mattercomponent is paper evaluates common methods for thedetermination of aluminum concentration in wastewatere main results are summarized as follows

Considering the measuring range of used analyticalmethods the GFAAS allows detection of the aluminumcontent in samples ranging from 001 to 01mgmiddotLminus1 butanalysis of mineralized samples can be stretched to rangeup to 05mgmiddotLminus1 by diluting 5 times in very good eectIncreasing the dilution multiplicity leads to a reduction inthe accuracy of the results to an unacceptable level Col-orimetric analysis can give similar results to GFAAS withinrange up to 025mgmiddotLminus1 e detection range of aluminumcontent in sludge samples can be extended up to 20mg inthe case of mineralized and diluted samples but read-outresults were indicative Whereas the FAAS method isrecommended for samples with a aluminum concentrationof 5 to 100mgmiddotLminus1 At low aluminum concentrations lessthan 4mgmiddotLminus1 the accuracy of the assay is unsuitable forFAAS e detection limits determined in this work wererespectively 002mgmiddotLminus1 for GFAAS method 007mgmiddotLminus1for colorimetric method and 40mgmiddotLminus1 for FAAS

e aluminum absorbance depends on the samplesrsquo pHand the form of aluminum which is introduced into thesystem Aluminum hydroxide is not fully atomized attemperatures generated in the standard acetylene umlame Ithas to be raised by the addition of N2O e umlame atomicabsorption spectrometry gives reproducible results for thealuminum concentration above 5mgmiddotLminus1 and it was toohigh to compare the aluminum content with other methodsfor the same analyzed samples erefore it is necessary toanalyze supernatant samples using both types of atomicabsorption spectrometry when an analyte content umluc-tuates between one of the detection limit scales

In the colorimetric method the absorbance value de-pends not only on the aluminum concentration but also on

y = 09067x

y = 09733x

0

2

4

6

8

10

12

14

0

01

02

03

04

05

06

000 007 014 022 028 034 041 048

RSD

()

Read

-out

alum

inum

conc

entr

atio

n(m

g Lndash1

)

Insert aluminum concentration (mg Lndash1)

GFAAS ()ECR ()

ECR methodGFAAS methodReal

Figure 9 Comparison of GFAAS aluminum concentration determinations and colorimetric method in relation to the actual value

Al2(SO4)3 + NaOH

SAX 18PAX 25

PAX 19H0

Al2(SO4)3

020406080

100120140160180

0 30 60 90 120 150 180

Qe (

mg

gndash1)

Ce (mg Lndash1)

Figure 10 Adsorption of aluminum by sludge for dierent types ofcoagulants


the reaction time and pH A simple modification of thecolorimetric method consisting in adjustment of suitablebuffer capacity of the sample allows to determine the alu-minum content in sewage sludge after its acidic minerali-zation To neutralize acidity impact it is necessary to use thestronger acetate buffer (046mM) which protected erio-chrome cyanine R before the decomposition

e low value of pH decreased the absorbance Highacetate buffer concentrations led to absorption decreasedespite the relatively high pH value of the sample Wespeculate that high ionic strength of the acetate bufferhampered the aluminum complex formation

Determination of aluminum content in samples byGFAAS is a more challenging method Particular attentionshould be paid to the inhomogeneity of analyzed sampleswhich may lead to substantial absorption intensity varia-tions Reagents of high analytical grade ultra pure water andhigh quality graphite tube should be applied

Determination of aluminum content by spectrophoto-metric method may be a useful and cheap alternative foranalyses carried out by atomic adsorption spectroscopiesespecially when concentrations of an analyte at the upperlimit of the GFAAS or the lower limit of the FAAS areconcerned However it should be noticed that atomic ab-sorption spectrometry determines the total content of alu-minum either in a free ionic or complexed forms e lattermay be characterized by lower stability than the Al(ECR)3

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon reasonablerequest

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

e authors wish to thank Mr Jakub Kubicki (Institute ofGeneral and Ecological Chemistry Lodz University ofTechnology) andMrs Jadwiga Albinska (Institute of Generaland Ecological Chemistry Lodz University of Technology)for technical assistance

References

[1] M Kulis and A Tylkowska-Siek Fizyczne Rozmiary ProdukcjiZwierzecej w 2015 r Głowny Urzad Statystyczny Departa-ment Rolnictwa Warsaw Poland 2016

[2] D Boruszko and W Dabrowski ldquoBadania efektywnosciprocesu flotacji i własciwosci osadow poflotacyjnych zpodczyszczania sciekow mleczarskichrdquo Inzynieria i OchronaSrodowiska vol 17 no 2 pp 269ndash280 2014

[3] K Szwedziak ldquoCharakterystyka osadow sciekowych i rolniczewykorzystanierdquo Inzynieria Rolnicza vol 4 pp 297ndash302 2006

[4] J B Bien and K Wystalska ldquoEnergetyczne wykorzystanieosadow sciekowychrdquo Przemysł Chemiczny vol 94 no 9pp 1496ndash1499 2008

[5] D Hawke J Powell and S Simpson ldquoEquilibrium modellingof interferences in the visible spectrophotometric de-termination of aluminium(III) comparison of the chromo-phores chrome azurolS eriochrome cyanine R andpyrocatechol violet and stability constants for eriochromecyanine R-aluminium complexesrdquo Analytica Chimica Actavol 319 no 3 pp 305ndash314 1996

[6] W Dougan and A Wilson ldquoe absorptiometric de-termination of aluminium in water A comparison of somechromogenic reagents and the development of an improvedmethodrdquo Analyst vol 99 no 1180 pp 413ndash430 1974

[7] Polish Standard Jakosc Wody-Oznaczanie Glinu-MetodyAtomowej Spektrometrii Absorpcyjnej PN-EN ISO 12020Polish Standard Warsaw Poland 2002

[8] A Shokrollahi M Ghaedi M S Niband and H R RajabildquoSelective and sensitive spectrophotometric method for de-termination of sub-micro-molar amounts of aluminium ionrdquoJournal of Hazardous Materials vol 151 no 2-3 pp 642ndash6482008

[9] A G G Dionisio A M Dantas de Jesus R S Amais et alldquoOld and new flavors of flame (furnace) atomic absorptionspectrometryrdquo International Journal of Spectroscopyvol 2011 Article ID 262715 30 pages 2011

[10] Polish Standard Oznaczanie Glinu Metoda zEriochromocyjanina R PN-C-04605-02 Polish StandardWarsaw Poland 1992

[11] W Hermanowicz J Dojlido and W Dozanska Fizyczno-Chemiczne Badanie Wody i Sciekow Arkady WarsawPoland 1999

[12] W Siriangkhawut S Tontrong and P ChantiratikulldquoQuantitation of aluminium content in waters and soft drinksby spectrophotometry using eriochrome cyanine Rrdquo ResearchJournal of Pharmaceutical Biological and Chemical Sciencesvol 4 no 3 pp 1154ndash1161 2013

[13] B Perkin-Elmer Analytical Methods for Atomic AbsorptionSpectroscopy e Perkin-Elmer Corp Norwalk CT USA1996

[14] I Narin M Tuzen and M Soylak ldquoAluminium de-termination in environmental samples by graphite furnaceatomic absorption spectrometry after solid phase extractionon Amberlite XAD-1180pyrocatechol violet chelating resinrdquoTalanta vol 63 no 2 pp 411ndash418 2004

[15] J Tria E C V Butler P R Haddad and A R BowieldquoDetermination of aluminium in natural water samplesrdquoAnalytica Chimica Acta vol 58 no 2 pp 153ndash165 2007

[16] C L Craney K Swartout F W Smith and C D WestldquoImprovement of trace aluminum determination by elec-trothermal atomic absorption spectrophotometry usingphosphoric acidrdquo Analytical Chemistry vol 58 no 3pp 656ndash658 1986

[17] C Marin A Tudorache and L Vladescu ldquoAluminium de-termination and speciation modelling in groundwater fromthe area of a future radioactive waste repositoryrdquo RevistadeChimie (Bucharest) vol 5 pp 431ndash438 2010

[18] Agilent Technical Overview+e Role of Chemical Modifiers inGraphite Furnace Atomic Absorption Spectrometry 5991-9286EN Agilent Santa Clara CA USA 2018

[19] P Bermejo-Barrera E Beceiro-Gonzalez and A Bermejo-Barrera ldquoUse of Pd-Mg(NO3)2 as matrix modifier for thedetermination of aluminum in water by electrothermal at-omization atomic absorption spectrometryrdquo MicrochemicalJournal vol 45 no 1 pp 90ndash96 1992

[20] L M Voth-Beach and D E Shrader ldquoInvestigations of areduced palladium chemical modifier for graphite furnace


atomic absorption spectrometryrdquo Journal of AnalyticalAtomic Spectrometry vol 2 no 1 pp 45ndash50 1987

[21] S Noremberg M Veiga D Bohrer et al ldquoDetermination ofaluminum and silicon in bovine liver by graphite furnaceatomic absorption spectrometry after dissolution with tet-ramethylammonium hydroxiderdquo Analytical Methods vol 7no 2 2014

[22] L Pszonicki and A M Essed ldquoPalladium and magnesiumnitrate as modifiers for the determination of lead by graphitefurnace atomic absorption spectrometryrdquo Chemia Anali-tyczna (Warsaw) vol 38 pp 771ndash778 1993

[23] R Sturgeon ldquoGraphite furnace atomic absorption spec-trometry fact and fictionrdquo Freseniusrsquo Zeitschrift fur analyti-sche Chemie vol 324 no 8 pp 807ndash818 1986

[24] N R Bader and B Zimmermann ldquoSample preparation foratomic spectroscopic analysis an overviewrdquo Advances inApplied Science Research vol 3 pp 1733ndash1737 2012

[25] X H Guan G H Chen and C Shang ldquoATR-FTIR and XPSstudy on the structure of complexes formed upon the ad-sorption of simple organic acids and aluminum hydroxiderdquoJournal of Environmental Sciences vol 19 no 4 pp 438ndash4432007

[26] J D Hem and C E Roberson ldquoForm and Stability of alu-minum hydroxide complexes in dilute solutionrdquo in Chemistryof Aluminum in Natural Water Geological Survey Water-Supply Paper 1827-A United States Government PrintingOffice Washington DC USA 1967


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well-recognized ability of aluminum to form colourfulcomplexes with organic compounds such as eriochromecyanine R (3Prime-sulfo-33prime-dimethyl-4-hydroxyfuchson-55prime-dicarboxylic (ECR)) (Figure 1) catechol violet [5] or alu-minon [6]

Nowadays modern analytical techniques such as atomicabsorption spectrometry (AAS) and inductively coupledplasma spectrometry (ICP) have challenged classic colori-metric analysis Both methods are quite expensive and re-quire considerable expertise In this study aluminumconcentration in wastewater has been determined bymodied spectrophotometric method which is characterizedby good precision high reproducibility low cost andsimplicity Flame and graphite furnace atomic absorptionspectrometries [7] were used as reference methodologies

Aluminum is an amphoteric element with the lowestsolubility at neutral pH when it precipitates as aluminumhydroxide Al(OH)3 Its solubility increases in either acidic oralkaline solutions Aluminum can form complexes with ECRgiving stable compounds such as Al-ECR3 or Al-ECR2OH inthe range of pH 5 to 6 [8] (Figure 2) erefore during theanalysis it is necessary to take into account the impact ofsolution pH on the structure of aluminum-ECR complexes

An important issue aecting the metalsrsquo determinationin complex samples is the interfering eect of matrixcomponents especially in highly saline samples includingseawaters dialysis solutions or mineralisates is matrixeect can be corrected by the careful sample mineralizationand the standard addition calibration method e pHoptimization for the signal to noise enhancement is man-datory [9]

2 Experimental

21 e Dairy Sewage Materials e examined sewage wasgenerated in the production of cottage cheese in the dairyfactory located in Lodz region Postproduction sewage isdrained to the factory sewage pretreatment plant whichconsists of three aerated balancing tanks followed by thesedimentation tank Aluminum coagulants were added tothe former to keep the pH at the 65 level Wastewater wasdischarged into the municipal sewage system after the four-day treatment time Samples were collected from balancingtanks in a two-week period over the whole 2017 year

211 e pH Optimization e experimental studies werecarried out to get the information about impact of acetatebuer concentration and pH value on spectrophotometricECR method for determination of aluminum content indairy sewage samples e correct solution pH was main-tained by using acetate buer e various concentrations ofacetate buer as well as dierent ratios of buer componentswere investigated e buer was prepared by mixingCH3COONamiddot3H2O with CH3COOH (Chempur Piekary SlPoland)

212 Measurements of the UV-Vis Spectra Maximum ab-sorbance wavelength for both eriochrome cyanine R and

complex of Al-ECR was determined e ECR was suppliedby POCH (Gliwice Poland)e spectra were measured on aUV-Vis spectrophotometer (2041-PC Shimadzu Japan)e reference sample was deionized water and the analyzedsamples contained aluminum in the form of eitherKAl(SO4)212H2O (Chempur) or polyaluminum chloride(Kemira PAX) at concentration of 74middot10minus2mMe sampleswere prepared in accordance with the procedure for de-termining the aluminum content in environmental samplesas described in the Polish Standard [10]

213 Mineralization of the Samples Due to the highcontent of organic compounds in the samples the driedsamples of the dairy sludge were mineralized before thealuminum content was determined e each sludgemineralization was made by closed microwave reactionsystem Multiwave 300 (Anton Paar USA) e averagemass of the tested samples was about 01 g e mixture of6 1mL (866mM HNO3 (Chempur) and 117mM HCl(Chempur)) was applied In the next step the mineralisateswere lled up to 100ml with deionized water e sameacid mixture was also added in the course of preparing thecalibration curves for mineralisates e oxidative eect ofHNO3HCl mixture on absorbance of emergent complexAl-ECR3 was also investigated e acid mixture concen-tration used for calibration curves was gradually increasedfrom 01mM to 10mM e constant aluminum and theECR doses (74middot10minus2 and 373middot10minus2 mM respectively) wereapplied

214 Measurements of the Absorption Colorimetric Complexe absorption intensity of the tested aluminum complexwas measured using Spekol 11 colorimeter (Carl-Zeiss Jena

CH3

O

O

HOO

O

OSO

OO

Na

NaNa

CH3

Figure 1 e chemical structure of eriochrome cyanine R (ECR)

ML3

MLH ML3H

ML2OH

0

20

40

60

80

100

20 25 30 35 40 45 50 55 60 65 70 75 80

Mol

ar p

erce

ntag

e of

com

plex

Sample pH value

Figure 2 e types of complexes Al3+-ECR depending on solutionpH μ 01M KNO3 [8]
























001020304050607

300 400 500 600 700

Abso

rptio

n (mdash

)

Wavelength (nm)


ndash02ndash01

00102030405

0 1 2 3 4 5 6 7 8 9 10

Abso

rban

ce (mdash

)

HNO3HCl (mM)



ndash02ndash01

00102030405

2531374349556167

Abso

rban

ce (mdash

)

pH value (mdash)


y = 12636x

y = 09699x

0

02

04

06

0 01 02 03 04 05

Abso

rban

ce (mdash

)




0005

01015

02025

03035

500 520 540 560 580 600

Abso

rptio

n (mdash

)

Wavelength (nm)















0010203040506

0 01 02 03 04 05

Abso

rban

ce (mdash

)


Series 1Series 2






4 Conclusions





y = 09067x

y = 09733x

0

2

4

6

8

10

12

14

0

01

02

03

04

05

06

000 007 014 022 028 034 041 048

RSD

()

Read

-out

alum

inum

conc

entr

atio

n(m

g Lndash1

)


GFAAS ()ECR ()



Al2(SO4)3 + NaOH

SAX 18PAX 25

PAX 19H0

Al2(SO4)3

020406080

100120140160180

0 30 60 90 120 150 180

Qe (

mg

gndash1)

Ce (mg Lndash1)







Data Availability




Acknowledgments


References



































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls


























001020304050607

300 400 500 600 700

Abso

rptio

n (mdash

)

Wavelength (nm)


ndash02ndash01

00102030405

0 1 2 3 4 5 6 7 8 9 10

Abso

rban

ce (mdash

)

HNO3HCl (mM)



ndash02ndash01

00102030405

2531374349556167

Abso

rban

ce (mdash

)

pH value (mdash)


y = 12636x

y = 09699x

0

02

04

06

0 01 02 03 04 05

Abso

rban

ce (mdash

)




0005

01015

02025

03035

500 520 540 560 580 600

Abso

rptio

n (mdash

)

Wavelength (nm)















0010203040506

0 01 02 03 04 05

Abso

rban

ce (mdash

)


Series 1Series 2






4 Conclusions





y = 09067x

y = 09733x

0

2

4

6

8

10

12

14

0

01

02

03

04

05

06

000 007 014 022 028 034 041 048

RSD

()

Read

-out

alum

inum

conc

entr

atio

n(m

g Lndash1

)


GFAAS ()ECR ()



Al2(SO4)3 + NaOH

SAX 18PAX 25

PAX 19H0

Al2(SO4)3

020406080

100120140160180

0 30 60 90 120 150 180

Qe (

mg

gndash1)

Ce (mg Lndash1)







Data Availability




Acknowledgments


References



































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls
















0010203040506

0 01 02 03 04 05

Abso

rban

ce (mdash

)


Series 1Series 2






4 Conclusions





y = 09067x

y = 09733x

0

2

4

6

8

10

12

14

0

01

02

03

04

05

06

000 007 014 022 028 034 041 048

RSD

()

Read

-out

alum

inum

conc

entr

atio

n(m

g Lndash1

)


GFAAS ()ECR ()



Al2(SO4)3 + NaOH

SAX 18PAX 25

PAX 19H0

Al2(SO4)3

020406080

100120140160180

0 30 60 90 120 150 180

Qe (

mg

gndash1)

Ce (mg Lndash1)







Data Availability




Acknowledgments


References



































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls







4 Conclusions





y = 09067x

y = 09733x

0

2

4

6

8

10

12

14

0

01

02

03

04

05

06

000 007 014 022 028 034 041 048

RSD

()

Read

-out

alum

inum

conc

entr

atio

n(m

g Lndash1

)


GFAAS ()ECR ()



Al2(SO4)3 + NaOH

SAX 18PAX 25

PAX 19H0

Al2(SO4)3

020406080

100120140160180

0 30 60 90 120 150 180

Qe (

mg

gndash1)

Ce (mg Lndash1)







Data Availability




Acknowledgments


References



































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








Data Availability




Acknowledgments


References



































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls

















Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




AluminuminEffluentsandSludgesfromthePreliminary...

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