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

Journal article (2014)

Authors

A Krzyzaniak External organisation
B Schuur External organisation
A.B. de Haan ChemE/Transport Phenomena - AS
Research Group
ChemE/Transport Phenomena (AS) (TU Delft)
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Published Date

2014

Language

English

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Faculty

Applied Sciences

Department

ChemE/Chemical Engineering

Research Group

ChemE/Transport Phenomena

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.