Equilibrium studies on lacticacid extraction with N,N-didodecylpyridin-4-amine (DDAP) extractant

A Krzyzaniak, B Schuur, AB de Haan

Research output: Contribution to journalArticleScientificpeer-review

43 Citations (Scopus)

Abstract

The extractionofaqueouslacticacid(LA)bytheextractantN,N-didodecylpyridin-4-amine(DDAP)dilutedin 1-octanolwasstudiedatthreetemperatures(298K,310Kand328K)inabatchsystemforaninitial concentrationof0.013M(0.12wt%)andarangeof Vorg/Vaq ratios(0.02¿1). Areactiveextractionmodelbased on massactionlawwasappliedtodescribetheexperimentaldata.Theparametersofthismodel,including aqueousphasedissociation,andaheterogeneouscomplexationwithstoichiometrycoefficientandcomplexa- tionconstantwere fittedtotheexperimentaldata.Theaqueousphasedissociationconstantswere fitted for thethreetemperatures,fromwhichtheenthalpyandentropyofdissociationwerefoundusingaVan'tHoff- plot.Thefoundvaluesare ¿Hd¼ 2.12 104J mol 1 and ¿Sd¼1.44 102 J mol 1 K 1. Theequilibrium constantsfor298K,310Kand328Kweredeterminedtobe570.42L/mol,349.77L/moland175.46L/mol, respectively.Thestoichiometrycoefficientwasfoundindependentontemperature,havingavalueof1.2.Using a Van'tHoffplot,thethermodynamicconstantsforthecomplexationwereestimatedat ¿Hc¼ 3.19 104 J mol 1 and ¿Sc¼ 0.54 102 J mol 1 K 1. Thedevelopedmodelwasusedforshort- cut calculationsonmultistageextraction ¿ backextractionoperations.Byapplyingback-extractionathigher temperature,atatmosphericpressureand T¼373Kwithwash/extractratio(W/E)¼5.4,theinitial0.013mol/L could beconcentratedtobetween0.041mol/Land0.078 mol/L lacticacid(concentrationfactorrangingfrom 3.15to6.06).Pressurizedrecoveryat413Kallowsforconcentrationsupto0.112¿0.21M(concentrationfactor rangingfrom8.66to16.66).Eventhoughsuchresultsareclearlyoutperformingthepreviouslyreported values,additionalpolishingtechniquesarerequired(i.e.evaporation)toobtainpureproductofhighquality.
Original languageEnglish
Pages (from-to)236-243
Number of pages8
JournalChemical Engineering Science
Volume109
Publication statusPublished - 2014

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