Research Article Spectroscopic and Thermogravimetric...

Research ArticleSpectroscopic and Thermogravimetric Investigation ofCd(II) Dinonyldithiophosphate Removal of Cadmium fromAqueous Solutions

Nermin Biricik1 Hadice Budak Guumlmguumlm2 and Bahattin Guumlmguumlm1

1Department of Chemistry Faculty of Science Dicle University 21280 Diyarbakir Turkey2Department of Physics Faculty of Science Dicle University 21280 Diyarbakir Turkey

Correspondence should be addressed to Hadice Budak Gumgum hbudakggmailcom

Received 22 January 2015 Revised 1 April 2015 Accepted 1 April 2015

Academic Editor Henryk Kozlowski

Copyright copy 2015 Nermin Biricik et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Dinonyldithiophosphoric acid (HDDTP) was synthesised from the reaction of phosphorus pentasulphide and nonyl alcoholDinonyldithiophosphate complex of cadmium [Cd(DDTP)

2] was prepared by mixing solutions of Cd(II) with HDDTP in ethanol

at room temperatureThe acid and its complex were characterised by elemental analysis and spectroscopyThe thermal behaviour ofCd(DNDTP)

2was investigated by thermogravimetric analysis Removal ofCd(II) fromaqueousmedia byHDDTP solutionwas also

studiedThe optimum conditions for removal of Cd(II) were investigated for effects of solvent pH contact time concentration andinorganic anions Cd(II) was quantitatively removed from aqueous solutions at the pH range of 05 lt pH lt 6 under the conditionsthat the stoichiometric ratio of HDDTPCd(II) ge21 It can be stated that contact of the Cd(II) with HDDTP was sufficient forquantitative removing of cadmium from acidic aqueous solutions

1 Introduction

Organodithio compounds are widely used in chemical andindustrial applications [1ndash3] Due to the synthesis andpurifying challenges of long chains dialkyldithiophosphoricacids their use in experiments was rare [2 4] althoughlong chains dialkyldithiophosphoric acids are more easilytransferred into the organic phase [5] andmore stable againsthydrolysis than the short-chain ones [6] The well-knownlubricant zinc dialkyldithiophosphate (ZDDTP) has beenextensively investigated [7] but only a few articles have beenpublished on the thermal properties of the other heavy metaldialkyldithiophosphates [8 9] Similarly there are only afew studies on Cd(II) dialkyldithiophosphates for its removalfrom aqueous solutions [10ndash14] but there are no articles onCd(II) dinonyldithiophosphate

Cadmium is one of the most toxic heavy metals forliving organisms One of the important natural heavy metalpollution sources is phosphate rocksphosphorus fertilizersDuring the production of phosphorus fertilizers dangerousamounts of heavy metals pollute the environment The main

source of cadmium accumulation in the agricultural landsis the phosphorus fertilizers and its restriction is almostimpossible [15] Thus cadmium is one of the common envi-ronmental contaminants and widely distributed around theworld

Theother important pollution sources are different indus-trial activities such as plating of metal mining pigmentspolyvinyl chloride plastics petrochemicals alloy and steelindustries andmunicipal discharge-wastewater [16] Accord-ing to the international standards the threshold level of Cd(II)concentration should be lower than 001mgL in wastewaterused for irrigation [17] Therefore it is necessary to eliminateCd(II) from contaminated waters

Because of its high mobility in soil and plant systemand easy accumulation cadmium may cause toxicities suchas cancer (lung and prostate) kidney damage and bonediseases [18] To reduce or remove Cd(II) from wastewateror contaminated waters various methods have been devel-oped including adsorption [19ndash22] biosorption [23 24] ionexchange [25] hydrogel [26] and chemical precipitation-extraction [27]

Hindawi Publishing CorporationJournal of ChemistryVolume 2015 Article ID 695324 5 pageshttpdxdoiorg1011552015695324

2 Journal of Chemistry

C9H19O

C9H19O

P

SSH

+ Cd2+ +

OC9H19

S

P

HS Oc9H19

C9H19O

C9H19O

P

SS

SS

Cd P

Oc9H19

Oc9H19

+ 2H+

Scheme 1

In the present study dinonyldithiophosphoric acid andits complex of Cd(II) were prepared and characterised byspectroscopic techniques and thermal analysis The removalof Cd(II) from aqueous solutions by using dinonyldithio-phosphoric acid was investigated

2 Materials and Methods

21 Preparation and Characterisation of HDDTP andCd(DDTP)

2 HDDTP was prepared from the reaction of

phosphorus pentasulphide and nonyl alcohol by usinga microwave oven (CEM-MDS 2000 Matthews USA)according to a previously published method [5] and tomake a sufficiently pure compound the method describedin the literature [6] was modified The obtained mixture wascooled and the unreacted solid part was filtered The oilyacid was converted to calcium salt by neutralisation withlime slurry at room temperature The salt was separated andwashed with hexane and acidified with 3M H

2SO4 The free

dinonyldithiophosphoric acid floating on top of aqueousphase was separated as a yellowish-green viscous liquid with98 purity

4C9H19OH + P

2S5997888rarr 2 (C

9H19O)2PSSH +H

2S (1)

An adequate amount of 10minus2M solutions of viscous oilHDDTP and Cd(II) in ethanol is mixed at room temperatureand Cd(DDTP)

2was obtained as white precipitate with

melting point 285∘C (see Scheme 1)The prepared acid and its complex were characterised by

elemental analysis (EA) ultraviolet-visible (UV-vis) infrared(IR) spectrophotometers and inductively coupled plasma-optical emission spectrometry (ICP-OES) and the thermalbehaviour of Cd(DDTP)

2was investigated by thermogravi-

metric analysis (TGA) Elemental analysis was carried outusing a CHNS-O elemental analyser (Carlo Erba EA 1108Milan Italy) UV-vis spectra of the samples dissolved in CCl

4

were recorded in the range 200ndash900 nmby aUVvisible spec-trophotometer (Unicam-UV2-100 Cambridge UK) using a1 cm quartz cell The IR spectra were recorded on a Fouriertransform IR (FTIR) spectrometer (Midac Co M SeriesCosta Mesa CA USA) as neat liquid using a NaCl cell inthe range 400ndash4000 cmminus1 The concentrations of Cadmiumwere determined by an ICP-OES (Perkin Elmer 2100 DVMassachusetts USA) at 228802 nm The TG measurementwas performed using a thermogravimetric analyser (Shi-madzu TGA-50 Kyoto Japan) with a temperature range fromroom to 800∘C at the rate of 20∘Cminminus1 under nitrogen(20mLminminus1) atmosphere

22 Experiments on Cd(II) Removal from Aqueous SolutionsWe have prepared solutions of HDDTP (2sdot10minus2M) in thedifferent solvents such as kerosene benzene 119899-hexanepetroleum ether and carbon tetrachlorideThe stock solutionof cadmium (1sdot10minus2M) was also prepared in distilled waterAll of the chemicals were of analytical reagent grade Removalof Cd(II) from aqueous solutions to the organic phase wasinvestigated as a function of pH for various anions solventsextractant concentration and extraction times Extractionor contact experiments related effect of time and pH wereperformed between 1 and 5 minutes and pH 05 and 60respectively Removal of Cd(II) using HDDTP was carriedout from different 01M aqueous solution of NaClO

4 NaCl

NaBr NaNO3 and CH

3COONa salts by stirring equal vol-

umes (25mL) of 10minus3M organic and aqueous phases at roomtemperature in a conventional separation funnel at differenttimes (min)ThepHvalueswere adjusted by adding sulphuricacid or sodium hydroxide and the pH values were measuredwith a pHmeter (Jenway 3010 LondonUK) After separationof the phases an aliquot of the aqueous part was analysed byan ICP-OES for the particular Cd(II) ion concentrations at228802 nm

The recovery percentage (119877) of Cd(II) can be calculatedas follows

119877 () =[119862119899+]0minus [119862119899+]

[119862119899+]0

times 100 (2)

where [119862119899+]0is initial concentration of the Cd(II) in the

aqueous phase and [119862119899+] is the concentration in the aqueousphase after extraction

3 Result and Discussion

31 Characterisation of HDDTP and Cd(DDTP)2 Potentio-

metric titration of the acid with 01M NaOH showed that theproduct contained 98 HDDTP which is a yellowish-green viscous oil The elemental analysis results for(C9H19O)2PSSH Analytical calculated () C 565 H

102 S 167 and found values () C 568 H 103 S 165Elemental analysis of the recovered white solid Cd(DDTP)

2

(melting point 285∘C) was C 493 H 87 S 146 P 71 andCd 128 for analytical calculations and the found values werefound to be C 495 H 82 S 144 P 70 and Cd 126 andthe results are in agreement with each other

The UV-vis absorption spectrum of dinonyldithiophos-phoric acid in CCl

4using a 1 cm quartz cell showed a peak at

267 nm can be attributed to 119899 rarr 120587lowast electronic transitionrelated gtP(=S)SH group (Table 1) The UV-vis absorption

Journal of Chemistry 3

Table 1 The UV-vis (120582 nm) and IR (V cmminus1) data of HDDTP and Cd(DDTP)2

Compound 120582maxnm

(P)ndashOndashCV cmminus1

PndashOndashCV cmminus1

(P=S)V cmminus1

(PndashS)V cmminus1

(SndashH)V cmminus1

HDDTP 267 1300ndash940 900ndash820 740ndash660 540 2550Cd(DDTP)2 294 1251ndash930 838ndash718 677ndash649 570 mdash

Wei

ght l

oss (

)

1 2

4993∘C

minus7037 ()

2071∘C

0800mgdiv

Temperature (∘C)

10 60 110 160 210 260 310 360 410 460

Figure 1 Thermogravimetric analysis of Cd(DDTP)2at a heating

rate of 20∘Cminminus1 under atmosphere of nitrogen

spectrumof Cd(DDTP)2was obtained at the same conditions

and relevant band was found 294 nm (Table 1) and can beattributed to the metal-ligand electronic transition

The recorded IR data of the acid and complex (Table 1)showed a good agreement with earlier studies carried outon other dialkyldithiophosphates [1 2] The IR spectral dataof cadmium dinonyldithiophosphate have been recorded atthe range of 4000ndash400 cmminus1 (Table 1) and it was observedthat the characteristic band of the dinonyldithiophosphoricacid at 2550 cmminus1 related to (P)SndashH stretching vibration wasvanished with the formation of Cd(DDTP)

2 and there was

no absorption record in the region Classically the strongintensity band present in the region 740ndash660 cmminus1 has beenattributed to P=S double bond and the absorption peak atsim540 cmminus1 has been assigned to PndashS single bond (Table 1)By formation of the complex the absorption values of thebands were significantly shifted and P=S peak was shifteddown while PndashS peak was shifted upThus P=S double bondstrength was decreased while PndashS single bond strength wasincreased This result was in agreement with the previousstudies on the other dialkyldithiophosphates [9 10 13] Thisapproach can be easily acceptable for simple M+ salt ofdithiophosphoric acids for example these two bands (P=Sand PndashS) of potassium butyldithiophosphate can be seen at703 cmminus1 and 550 cmminus1 respectively [13]

According to the obtained thermogram (Figure 1)Cd(DDTP)

2is stable at temperatures up to sim207∘C and

does not contain water As shown in Figure 1 Cd(DDTP)2

decomposes in three steps and the main weight loss ofthe complex takes place between 207 and 332∘C becauseof the decomposition of the organic part The total weightloss percentage of the Cd(DDTP)

2is 704 up to the

temperature 499∘CThe weight change is lower than 3 over332∘C temperature The results are in good agreement with

our earlier studies on heavy metal dialkyldithiophosphatecomplexes [9]

32 Cd(II) Removal from Aqueous Solutions Themolar ratioof dinonyldithiophosphoric acidcadmium has main influ-ence in the extraction process (Table 2(a)) Cd(II) was quanti-tatively recovered from the acidic aqueous solution under theconditions that the stoichiometric ratio of HDDTPCd(II)was gt21 When the experiment was performed with lowermolar ratio such as equal volumes of 1sdot10minus3M HDDTP and1sdot10minus3Mmetal solutionwasmixed the removal ratio ofCd(II)was found to be 60 A favourable result was obtained andCd(II) was quantitatively extracted from the aqueous solu-tion to organic phase when molar ratio of HDDTPCd(II)increased to 3 (Table 2(a)) The pH experiments on theextraction of Cd(II) showed that (Table 2(b)) it is possibleto suggest Cd(II) can be quantitatively extracted between pH05 and 6 The contact time of metal-ligand on the removalof Cd(II) was examined (Table 2(c)) and it was found that1-minute stirring time can supply quantitative removal ofcadmium

The experiment conducted on different solvents suchas kerosene benzene 119899-hexane petroleum ether and CCl

4

implies that there is no difference between solvents used(Table 2(d)) Therefore all the investigated solvents can beused in the removal of Cd(II) We have also investigatedthe effect of common inorganic anions such as NaClO

4

NaCl NaBr NaNO3 and CH

3COONa on the extractions

of Cd(II) from aqueous solution We have found that therewere no differences except for CH

3COONa salt (Table 2(e))

Cadmium acetate was also a stable complex and its solubilityin water was very high In addition our primary resultsshowed that the Cd(II) could not be recovered back by 1ndash5MH2SO4from organic to aqueous phase

Our results were in agreement with the studies relatedto extraction of Cd(II) by diethy- dipropyl- and dibutyldithiophosphates [10ndash14] In these studies they showed thatpH 3ndash5 is suitable for Cd(II) removal and they form differentCd(II) complexes in the basic pH in order to regenerate fromorganic phase to aqueous phase The compounds containinglong chain alkyl or more carbon are easily soluble in organicsolvents and their solubility in aqueous media decreasesIf the results were compared with our findings the effectof dinonyl group can easily be seen Cd(DDTP)

2with

long nonyl group is insoluble in water and very soluble inorganic solvents and 1 minute is sufficient for quantitativelyremoving of cadmium from aqueous media There was anacceptable agreement between the previous results and ourfindings on removing Cd(II) from aqueous solutions usingalkyldithiophosphates as extractants


Table 2 Determination of removed cadmium from aqueous solutions by dinonyl dithiophosphoric acid (a) Effect of HDDTP concentration(b) influence of pH of aqueous phase (c) influence of contact time (d) effect of solvents and (e) effect of salts (120582 228802 nm)

(a) Effect of HDDTP concentration (pH 3 time 3min solvent kerosene)

HDDTP conc (10minus3M) 05 10 20 30 40 50Extraction rate () Cd++ 28 60 100 100 100 100

(b) Influence of pH of aqueous phase (HDDTP 3sdot10minus3M time 3min solvent kerosene)

pH of aqueous phase 05 1 2 3 4 6Extraction rate () Cd++ 100 100 100 100 100 100

(c) Influence of contact time (HDDTP 3sdot10minus3M pH 3 solvent kerosene)

Time (Min) 1 2 3 4 5Extraction rate () Cd++ 100 100 100 100 100

(d) Effect of solvents (HDDTP 3sdot10minus3M pH 3 time 3min)

Solvents Kerosene Benzene 119899-Hexane Petroleum ether Carbon-tetrachlorideExtraction rate () Cd++ 100 100 100 100 100

(e) Effect of salts (HDDTP 3sdot10minus3M pH 3 time 3min solvent kerosene)

Salts (01M) NaClO4 NaCl NaBr NaNO3 CH3COONaExtraction rate () Cd++ 100 100 100 100 00

Present results showed that Cd(II) could be easilyremoved from the acidic aqueous solutions by HDDTPanyorganic solvent

4 Conclusions

Dinonyldithiophosphoric acid instantly reacts with Cd(II)to form a white solid complex at room temperature TheCd(DDTP)

2is stable up to sim207∘C and insoluble in water but

very soluble in organic solvents such as kerosene benzene119899-hexane petroleum ether and carbon tetrachloride andthese are suitable solvents for using HDDTP or its salt asextractants

The experiments concerning the influence of the concen-tration of HDDTPany solvent on removal of Cd(II) from theacidic aqueous solutions show that cadmium was quantita-tively removed under the conditions that the stoichiometricratio of HDDTPCd(II) ge21 The experiments related withpH of aqueous media show that Cd(II) can be removedcompletely from the acidic solutions at pH range of 05ltpHlt6 When the technique is applied on any acidic wastewateror sludge it does not require any pH adjustment and themethod can supply low costs Experiments related to effectof contact time for removal of Cd(II) showed that contactof the HDDTP with Cd(II) was sufficient for its quantitativeremoving Cd ions were quantitatively transferred to organicphase after 1min mixing of Cd(II) and HDDTP Because thepotential ecological risk of cadmium is relatively high it isnecessary to remove or reduce Cd(II) levels in the municipalor industrials discharges It can be concluded that HDDTP isan appropriate substance for removal of Cd(II) from acidicaqueous solutions

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J C Ramos A J Curtius and D L G Borges ldquoDiethyldithio-phosphate (DDTP) a review on properties general applica-tions and use in analytical spectrometryrdquo Applied SpectroscopyReviews vol 47 no 8 pp 583ndash619 2012

[2] AM Barnes K D Bartle andV R AThibon ldquoA review of zincdialkyldithiophosphates (ZDDPS) characterisation and role inthe lubricating oilrdquo Tribology International vol 34 no 6 pp389ndash395 2001

[3] I Haiduc ldquoThiophosphorus and related ligands in coordina-tion organometallic and supramolecular chemistry A personalaccountrdquo Journal of Organometallic Chemistry vol 623 no 1-2pp 29ndash42 2001

[4] T H Handley and J A Dean ldquoO1198741015840-dialkyl phosphorodithioicacids as extractants for metalsrdquo Analytical Chemistry vol 34no 10 pp 1312ndash1315 1962

[5] B Gumgum N Biricik A Baysal O Akba and G OzturkldquoPreparation and solvent extraction of nickel complex of O1198741015840-dinonyldithiophosphate and its application to spectrophoto-metric determination of nickel in sediment samplesrdquo Annali diChimica vol 96 no 11-12 pp 681ndash688 2006

[6] V F Toropova A R Garifzyanov and I E Panfilova ldquoStericand hydrophobic effects of substituents in extraction of metalcomplexes with OO-dialkyldithiophosphoric acidsrdquo Talantavol 34 no 1 pp 211ndash214 1987


[7] K-H Ohrbach G Matuschek A Kettrup and A JoachimldquoSimultaneous thermal analysis-mass spectrometry on lubri-cant systems and additivesrdquo Thermochimica Acta vol 166 pp277ndash289 1990

[8] S Y Wu and B Xie ldquoSynthesis and spectroscopic propertiesof (tetraazacyclotetradeca) center dot bis(OO1015840-bi(1-naphthyl)dithiophosphate) nickel or copper complexesrdquo Chinese Journalof Inorganic Chemistry vol 15 no 2 pp 267ndash271 1999

[9] N Biricik and B Gumgum ldquoThe preparation and thermo-analytical characterization of heavy metal complexes of OO1015840-dinonyldithiophosphaterdquo Thermochimica Acta vol 417 no 1pp 43ndash45 2004

[10] X Ying and Z Fang ldquoExperimental research on heavy metalwastewater treatment with dipropyl dithiophosphaterdquo Journalof Hazardous Materials vol B137 no 3 pp 1636ndash1642 2006

[11] J S Carletto R M Luciano G C Bedendo and E CarasekldquoSimple hollow fiber renewal liquid membrane extractionmethod for pre-concentration of Cd(II) in environmental sam-ples and detection by Flame Atomic Absorption SpectrometryrdquoAnalytica Chimica Acta vol 638 no 1 pp 45ndash50 2009

[12] R M Luciano G C Bedendo J S Carletto and E CarasekldquoIsolation and preconcentration of Cd(II) from environmentalsamples using polypropylene porous membrane in a hollowfiber renewal liquidmembrane extraction procedure and deter-mination by FAASrdquo Journal of HazardousMaterials vol 177 no1ndash3 pp 567ndash572 2010

[13] Y Xu Z Xie and L Xue ldquoChelation of heavy metals by potas-sium butyl dithiophosphaterdquo Journal of Environmental Sciencesvol 23 no 5 pp 778ndash783 2011

[14] Y Xu Y Chen and Y Feng ldquoStabilization treatment of theheavy metals in fly ash frommunicipal solid waste incinerationusing diisopropyl dithiophosphate potassiumrdquo EnvironmentalTechnology vol 34 no 11 pp 1411ndash1419 2013

[15] A W Al-Shawi and R Dahl ldquoThe determination of cadmiumand six other heavy metals in nitratephosphate fertilizer solu-tion by ion chromatographyrdquo Analytica Chimica Acta vol 391no 1 pp 35ndash42 1999

[16] J Duan and B Su ldquoRemoval characteristics of Cd(II) fromacidic aqueous solution by modified steel-making slagrdquo Chem-ical Engineering Journal vol 246 pp 160ndash167 2014

[17] N Gupta D K Khan and S C Santra ldquoAn assessment ofheavy metal contamination in vegetables grown in wastewater-irrigated areas of Titagarh West Bengal Indiardquo Bulletin ofEnvironmental Contamination and Toxicology vol 80 no 2 pp115ndash118 2008

[18] K J Yost L J Miles and R A Greenkorn ldquoCadmium simu-lation of environmental control strategies to reduce exposurerdquoEnvironmental Management vol 5 no 4 pp 341ndash352 1981

[19] G Yang L Tang X Lei et al ldquoCd(II) removal from aqueoussolution by adsorption on 120572-ketoglutaric acid-modified mag-netic chitosanrdquo Applied Surface Science vol 292 pp 710ndash7162014

[20] C Cheng J Wang X Yang A Li and C Philippe ldquoAdsorptionof Ni(II) and Cd(II) from water by novel chelating sponge andthe effect of alkali-earth metal ions on the adsorptionrdquo Journalof Hazardous Materials vol 264 pp 332ndash341 2014

[21] M Xu Q Chang W Zhang and Q Du ldquoRemoval of cadmium(II) from aqueous solution using chitosan modified with thio-glycolic acidrdquo Fresenius Environmental Bulletin vol 22 no 1App 163ndash170 2013

[22] D Bingol ldquoRemoval of cadmium (II) from aqueous solutionsusing a central composite designrdquo Fresenius EnvironmentalBulletin vol 20 no 10 pp 2704ndash2709 2011

[23] G Edris Y Alhamed and A Alzahrani ldquoBiosorption ofcadmium and lead from aqueous solutions byChlorella vulgarisbiomass equilibrium and kinetic studyrdquo Arabian Journal forScience and Engineering vol 39 no 1 pp 87ndash93 2014

[24] C G Rocha D A M Zaia R V D S Alfaya and A A D SAlfaya ldquoUse of rice straw as biosorbent for removal of Cu(II)Zn(II) Cd(II) and Hg(II) ions in industrial effluentsrdquo Journal ofHazardous Materials vol 166 no 1 pp 383ndash388 2009

[25] Y Zheng C Xiong C Yao et al ldquoAdsorption performance andmechanism for removal of Cd(II) from aqueous solutions byD001 cation-exchange resinrdquo Water Science amp Technology vol69 no 4 pp 833ndash839 2014

[26] A M Atta H S Ismail and A M Elsaaed ldquoApplication ofanionic acrylamide-based hydrogels in the removal of heavymetals from waste waterrdquo Journal of Applied Polymer Sciencevol 123 no 4 pp 2500ndash2510 2012

[27] Y Shengke and C Yuyun ldquoSynergistic effects of chelating pre-cipitation and flocculation on removal of cadmium amino-complex from wastewaterrdquo Fresenius Environmental Bulletinvol 20 no 12 pp 3235ndash3240 2011

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

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Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


C9H19O

C9H19O

P

SSH

+ Cd2+ +

OC9H19

S

P

HS Oc9H19

C9H19O

C9H19O

P

SS

SS

Cd P

Oc9H19

Oc9H19

+ 2H+

Scheme 1

In the present study dinonyldithiophosphoric acid andits complex of Cd(II) were prepared and characterised byspectroscopic techniques and thermal analysis The removalof Cd(II) from aqueous solutions by using dinonyldithio-phosphoric acid was investigated

2 Materials and Methods

21 Preparation and Characterisation of HDDTP andCd(DDTP)

2 HDDTP was prepared from the reaction of

phosphorus pentasulphide and nonyl alcohol by usinga microwave oven (CEM-MDS 2000 Matthews USA)according to a previously published method [5] and tomake a sufficiently pure compound the method describedin the literature [6] was modified The obtained mixture wascooled and the unreacted solid part was filtered The oilyacid was converted to calcium salt by neutralisation withlime slurry at room temperature The salt was separated andwashed with hexane and acidified with 3M H

2SO4 The free

dinonyldithiophosphoric acid floating on top of aqueousphase was separated as a yellowish-green viscous liquid with98 purity

4C9H19OH + P

2S5997888rarr 2 (C

9H19O)2PSSH +H

2S (1)

An adequate amount of 10minus2M solutions of viscous oilHDDTP and Cd(II) in ethanol is mixed at room temperatureand Cd(DDTP)

2was obtained as white precipitate with

melting point 285∘C (see Scheme 1)The prepared acid and its complex were characterised by

elemental analysis (EA) ultraviolet-visible (UV-vis) infrared(IR) spectrophotometers and inductively coupled plasma-optical emission spectrometry (ICP-OES) and the thermalbehaviour of Cd(DDTP)

2was investigated by thermogravi-

metric analysis (TGA) Elemental analysis was carried outusing a CHNS-O elemental analyser (Carlo Erba EA 1108Milan Italy) UV-vis spectra of the samples dissolved in CCl

4

were recorded in the range 200ndash900 nmby aUVvisible spec-trophotometer (Unicam-UV2-100 Cambridge UK) using a1 cm quartz cell The IR spectra were recorded on a Fouriertransform IR (FTIR) spectrometer (Midac Co M SeriesCosta Mesa CA USA) as neat liquid using a NaCl cell inthe range 400ndash4000 cmminus1 The concentrations of Cadmiumwere determined by an ICP-OES (Perkin Elmer 2100 DVMassachusetts USA) at 228802 nm The TG measurementwas performed using a thermogravimetric analyser (Shi-madzu TGA-50 Kyoto Japan) with a temperature range fromroom to 800∘C at the rate of 20∘Cminminus1 under nitrogen(20mLminminus1) atmosphere

22 Experiments on Cd(II) Removal from Aqueous SolutionsWe have prepared solutions of HDDTP (2sdot10minus2M) in thedifferent solvents such as kerosene benzene 119899-hexanepetroleum ether and carbon tetrachlorideThe stock solutionof cadmium (1sdot10minus2M) was also prepared in distilled waterAll of the chemicals were of analytical reagent grade Removalof Cd(II) from aqueous solutions to the organic phase wasinvestigated as a function of pH for various anions solventsextractant concentration and extraction times Extractionor contact experiments related effect of time and pH wereperformed between 1 and 5 minutes and pH 05 and 60respectively Removal of Cd(II) using HDDTP was carriedout from different 01M aqueous solution of NaClO

4 NaCl

NaBr NaNO3 and CH

3COONa salts by stirring equal vol-

umes (25mL) of 10minus3M organic and aqueous phases at roomtemperature in a conventional separation funnel at differenttimes (min)ThepHvalueswere adjusted by adding sulphuricacid or sodium hydroxide and the pH values were measuredwith a pHmeter (Jenway 3010 LondonUK) After separationof the phases an aliquot of the aqueous part was analysed byan ICP-OES for the particular Cd(II) ion concentrations at228802 nm

The recovery percentage (119877) of Cd(II) can be calculatedas follows

119877 () =[119862119899+]0minus [119862119899+]

[119862119899+]0

times 100 (2)

where [119862119899+]0is initial concentration of the Cd(II) in the

aqueous phase and [119862119899+] is the concentration in the aqueousphase after extraction

3 Result and Discussion

31 Characterisation of HDDTP and Cd(DDTP)2 Potentio-

metric titration of the acid with 01M NaOH showed that theproduct contained 98 HDDTP which is a yellowish-green viscous oil The elemental analysis results for(C9H19O)2PSSH Analytical calculated () C 565 H

102 S 167 and found values () C 568 H 103 S 165Elemental analysis of the recovered white solid Cd(DDTP)

2

(melting point 285∘C) was C 493 H 87 S 146 P 71 andCd 128 for analytical calculations and the found values werefound to be C 495 H 82 S 144 P 70 and Cd 126 andthe results are in agreement with each other

The UV-vis absorption spectrum of dinonyldithiophos-phoric acid in CCl

4using a 1 cm quartz cell showed a peak at

267 nm can be attributed to 119899 rarr 120587lowast electronic transitionrelated gtP(=S)SH group (Table 1) The UV-vis absorption






(P=S)V cmminus1

(PndashS)V cmminus1

(SndashH)V cmminus1


Wei

ght l

oss (

)

1 2

4993∘C

minus7037 ()

2071∘C

0800mgdiv

Temperature (∘C)

10 60 110 160 210 260 310 360 410 460






2 and there was






2is 704 up to the





4


4







2with















4 Conclusions







References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






(P=S)V cmminus1

(PndashS)V cmminus1

(SndashH)V cmminus1


Wei

ght l

oss (

)

1 2

4993∘C

minus7037 ()

2071∘C

0800mgdiv

Temperature (∘C)

10 60 110 160 210 260 310 360 410 460






2 and there was






2is 704 up to the





4


4







2with















4 Conclusions







References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of














4 Conclusions







References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of
































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Research Article Spectroscopic and Thermogravimetric...

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