Ionic liquids (ILs) can replace conventional solvents in separation processes, such as extractive distillation (ED), because of their ability to selectively separate azeotropic/close boiling mixtures. Four case studies were selected: ethanol/water (1-ethyl-3-methylimidazolium dicyanamide, [emim][N(CN)2], and ethylene glycol, EG), 1-hexene/n-hexane (no suitable IL found), methylcyclohexane/toluene (1-hexyl-3-methylimidazolium tetracyanoborate, [hmim][B(CN)4], and N-methyl-2-pyrrolidone, NMP), and ethylbenzene/styrene (4-methyl-N-butylpyridinium tetrafluoroborate, [4-mebupy][BF4], and sulfolane). Pilot plant experiments proved that the developed models for ED could well describe the experimental results.

Conceptual processes were designed for the ED of three case studies. The ethanol/water process with [emim][N(CN)2] reduced the energy requirements with 16 % compared to the process with EG, provided that proper heat integration is implemented. The methylcyclohexane (MCH)/toluene process with [hmim][B(CN)4] required about 50 % less energy with heat integration than the conventional process with NMP with heat integration.

The IL [4-mebupy][BF4] reduced the energy requirement most compared to the conventional distillation for the ethylbenzene/styrene process (43.2 %), which is 5 % lower than with extractive distillation with sulfolane. However, the capital expenditures were about 23 % higher than for the sulfolane process. It can be concluded from the total annual costs that all studied ED processes outperform the current distillation process to obtain high purity styrene, but that ILs do not perform better than sulfolane.

The general conclusion of these four examples is that only in some special cases ILs can be more advantageously applied than conventional solvents in extractive distillation. The key performance points for ED are a high selectivity and high capacity, next to the solvent recovery and heat integration.@en

Solventimpregnatedresinsarepromisingfortheremovalofpolarorganiccompoundsfromaqueous streams, buthavelowmass-transferrates. Athoroughunderstandingofthephenomenaoccurringinside the oresofthesolventimpregnatedresinisthereforerequired.Inthisstudyamathematicalmodelwas developed todescribethesimultaneousdiffusionandreaction.Thediffusionwasdescribedusingthe Maxwell¿Stefanapproachtowardsmulti-componentdiffusionandincludedthevolume-expansionof the organicphase.Themodelwasvalidatedusingexperimentaldatafromtheliteratureonthe extractionofphenolbyCyanex923impregnatedinmacro-porouspolypropylene.Themodeldescribed the experimentaldataasfunctionoftemperatureandinitialconcentrationaccuratelywithan R240.96 and aregressedreactionrateconstantwithaconfidence intervalof 76%. Analysisofthemodelresults revealedthatmulti-componenteffectsasdescribedbytheMaxwell¿Stefanmodelwereoflimited importance whereasthevolumeexpansionwasessentialtoaccuratelydescribetheexperimentaldata.@en

Enantioseparation through liquid extraction technology is an emerging field, e.g., enantioseparations of amino acids (and derivatives thereof), amino alcohols, amines, and carboxylic acids have been reported. Often, when a new selector is developed, the versatility of substrate scope is investigated. From an industrial point of view, the problem is typically approached the other way around, and for a target racemate, a selector needs to be found in order to accomplish the desired enantioseparation. This study presents such a screening approach for the separation of the enantiomers of DL-¿-methyl phenylglycine amide (DL-¿-MPGA), a model amide racemate with high industrial relevance. Chiral selectors that were reported for other classes of racemates were investigated, i.e., several macrocyclic selectors and Pd-BINAP complexes. It appeared very challenging to obtain both high extraction yields and good enantioselectivity for most selectors, but Pd-BINAP-based selectors performed well, with enantioselectivities up to 7.4 with an extraction yield of the desired enantiomer of 95.8%. These high enantioselectivities were obtained using dichloromethane as solvent. Using less volatile chlorobenzene or 1-chloropentane, reasonable selectivities of up to 1.7 were measured, making these the best alternative solvents for dichloromethane. Chirality 27:123¿130, 2015@en

Solvent impregnated resins (SIRs) were evaluated for the recovery of pyridine derivatives from an aqueous waste-stream containing also acetic acid and succinonitrile. For this purpose, a new solvent was developed, synthesized and impregnated in Amberlite XAD4. Sorption studies were used to determine the capacity, selectivity and the mass-transfer rate. A high capacity of 21 g 4-yanopyridine (CP) per kg SIR was found, with very high selectivity toward CP over the other solutes of at least 570. A modified Langmuir equation could describe the equilibrium sorption isotherm. Both the linear driving force model and a Fickian diffusion model were evaluated. The Fick-model described both regeneration and loading best. The CP-diffusivity through the solvent phase was estimated at 6.53 10 13 ± 2.5% m2 s 1. The model was validated using fixed-bed column experiments. The R2 values for this model ranged between 0.94 at a flow rate of 5 mL/min and 0.99 at a flow rate of 1 mL/min during the loading cycle. Due to mass-transfer limitations the breakthrough profiles were broad and breakthrough occurred after 5 or 23 bed volumes, for flow rates of 5 and 1 mL/min, respectively. Both acetic acid and succinonitrile broke through immediately due to the very high CP-selectivity of the SIR.@en

tLiquid¿liquid extraction using polymers followed by induced phase separation is a potential energyreducing technology for water¿salt separation. Ternary equilibrium data have been determined andreported for the (block co)poly ethers¿sodium chloride¿water systems at two different temperaturesat 298.15 K and 313.15 K and atmospheric pressure. The experimental data were correlated with theNRTL model, and the obtained binary interaction parameters to describe the ternary liquid¿liquid sys-tems at different temperatures are presented. The model predictions are in good agreement with theexperimental data.@en

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.@en

tLiquid¿liquid extraction using thermoresponsive polymers as solvents in aqueous two phase systemsfollowed by induced phase separation to recover the polymers is a potential technology for water¿saltseparations. Here we report for seven polymers on their ternary systems containing water, sodium sulfateand the (block co)poly ether. Equilibrium data were measured at 298.15 K and 313.15 K and atmosphericpressure. Empirical equations have been used to correlate the experimental equilibria for both temper-atures separately and the semi-empirical NRTL model has been applied with a temperature dependentparameter to describe the complete dataset for both temperatures together. Model predictions were ingood agreement with the experimental data.@en

An important element in the work-up of brines is the separation of different ions present. Usually, energy consuming technologies, such as multi-stage evaporation, reverse osmosis, crystallization, and nanofiltration, are used to bring the composition of the brine to the required specification. Fractionation of salts by liquid¿liquid extraction using thermo-responsive polymers is a novel concept. In the current study we have evaluated the fractional extraction of sodium chloride from brines containing sodium sulfate as well. Four different polymers (Dehypon LS 54, PPG 425, Pluronic L31 and Triton X ¿ 15) have been used. The quaternary systems of these polymers with water, sodium chloride and sodium sulfate have been obtained at 283.15 K and 298.15 K. From experiments at 298.15 K, it was concluded that the polymer Dehypon LS 54 showed the most interesting combination of extracted sodium chloride yield and selectivity of sodium chloride over sodium sulfate. The polymer losses to the feed (brine) phase were limited. Collected extract phases were subjected to a temperature increase to 323.15 K, 333.15 K, 343.15 K, and 353.15 K in order to study the polymer recovery by temperature induced phase splitting. It was found that at higher temperature the miscibility gap increased strongly and limited amounts of polymer remained in the aqueous phase.@en