Solubility of gallic acid in liquid mixtures of (ethanol + water) from (293.15 to 318.15) K

Solubilityofgallicacidinliquidmixturesof(ethanol+water)from(293.15to318.15)K

AdelNoubigha, ,Chokrijeribia,ArbiMgaidib,ManefAbderrabbaa

ab

LaboratoryofPhysicalChemistryofMaterials,PreparatoryInstituteforScienti candTechnicalStudiesofLaMarsa,CarthageUniversity,Bp51,2070LaMarsa,TunisiaIndustrialInorganicChemistryLaboratory,ChemistryDepartment,FacultyofScienceofTunis,TunisElManarUniversity,1060Tunis,Tunisia

articleinfoabstract

Thesolubilityofgallicacidin(water+ethanol)binarysolventswasdeterminedfrom(293.15to318.15)KatatmosphericpressureusingathermostattedreactorandUV/visspectrophotometeranalysis.Theeffectsofbinarysolventscompositionandtemperatureonthesolubilitywerediscussed.Itwasfoundthatgallicacidsolubilityin(water+ethanol)ingtheexperimentallymeasuredsolubilities,thethermodynamicpropertiesofdissolutionofthegallicacidsuchasGibbsenergy(DsolG°),molarenthalpyofdissolution(DsolH°),andmolarentropyofdissolution(DsolS°)werecalculated.

Ó2012ElsevierLtd.Allrightsreserved.

Articlehistory:

Received3March2012

Receivedinrevisedform5May2012Accepted19June2012

Availableonline29June2012Keywords:GallicacidSolubility

Mixedsolvents

TemperaturedependenceThermodynamicproperties

1.Introduction

Gallicacid(3,4,5-trihydroxybenzoicacid)anditsderivativesarephenoliccompoundscontainedinOliveMillWasteWater(OMWW)[1,2]andpresentinsomeplants,suchasgreenandblackteas[3],andoak[4].Theyareindustriallyimportantchemicalswidelyusedinorganicsynthesis,pharmaceutical,food,andinte-gratedcircuitmanufacturing.Thesephenoliccompoundsareanti-oxidant[5,6],anti-in ammatory[7],phytotoxicandtoxictobacteriaandusedincommonbiologicalwastewatertreatment[8–10].Thesolubilityofsolidcompoundsinpuresolventsandmixedsolventsplaysakeyroleinallcrystallizationprocesses[11].Moreover,solubilitydatainpuresolventsandmixedsolventscanbeconsideredashelpfulintheextractionandpuri cationpro-cessesoforganiccompoundsfromdifferentmatrices.

Insomerecentworks[12,13],solubilitiesofgallicacidinsev-eralpuresolventshavebeenmeasuredasafunctionoftempera-ture.However,inourknowledgenoexperimentalortheoreticalstudyconcerningthesolubilityofgallicacidinbinarysolventshasbeenreportedintheliterature.Asacontinuationofourearlierstudiesconcerningthephenoliccompoundssolubility[14–17],wereporthereontheeffectsofbinarysolventscompositionandtem-peratureonthesolubilityofgallicacid.Thesolubilitiesofgallicacidin(water+ethanol)mixedsolventswithethanolmolefrac-tionsof0.0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,and1.0,onaCorrespondingauthor.Tel.:+21698934601;fax:+21671746551.

E-mailaddresses:adel.anoubigh@ipest.rnu.tn,anoubigh@yahoo.fr(A.Noubigh).

0021-9614/$-seefrontmatterÓ2012ElsevierLtd.Allrightsreserved./10.1016/j.jct.2012.06.022

solute-freebasisweredeterminedatT=(293.15,298.15,303.15,308.15,313.15,and318.15)K.Obtaineddatawereusedtocalcu-lateappropriatedissolutionthermodynamicproperties.2.Materialsandmethods

Gallicacid(C7H6O5,MW=170.12,>98%pure)andethanolwerepurchasedfromSigma–Aldrich(Germany).Gallicacidwasusedwithoutpriortreatment,butstoredinadessicatorwithP2O5oncethebottlehasbeenopened.AbsoluteEthanolwasofanalyticalgrade(C2H6O,purity=99.8%,MW=46.07,d=0.79g/mL).Distilledwater(conductivityaround1.5lSÁcmÀ1)hasbeenused.

BinarysolventwerepreparedbymassusingaSartoriusCP225Danalyticalbalancewithanaccuracyof±0.01mg.Theuncertaintyinthemolefractionofmixedsolventswasestimatedtobewithin±0.0003.25gofbinarysolventswereintroducedintoadoublejacketedreactorthermostattedat(T±0.1)K(PolystatHuberCC2).Anexcessofthesolidgallicacidwasaddedtotheliquidphaseandthesolutionwascontinuouslystirredwithamagneticstirrer.Tochecktheequilibrium,asampleoftheliquidphasewastakenthrougha0.2lmporesyringe lterandtheconcentra-tionwasmeasuredbyUV/visiblespectrophotometry(BeckmanCoulterUV/visspectrophotometermodelDU-520)at300nm.Thewavelengthof300nmwasdeterminedtobethemostadequateforgallicacidquanti cationbecauseofthemaximumabsorbanceatthiswavelength.Whentheconcentrationofgallicacidintheli-quidphaseremainedconstant,itwasassumedthatthesystemwasatequilibrium.Severalequilibriumtimeshavebeentested(from1

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