Intensified reactive extraction of 4-hydroxypyridine with di(2-ethylhexyl) phosphoric acid in 1-octanol by using tributyl phosphate

The efficient separation of amphoteric organic compounds from dilute solutions is of great importance in the industrial field. In the present work, the reactive extractions of 4-hydroxypyridine(4-HP) with tributyl phosphate(TBP), di(2-ethylhexyl) phosphoric acid(D2EHPA) and TBP + D2EHPA dissolved in 1-octanol were investigated, respectively. The influences of the initial concentrations of TBP, D2EHPA and TBP + D2EHPA on distribution ratio(D) were discussed, as well as the reactive extraction mechanism were proposed. The obvious intensification effect was observed when the mixture of TBP and D2EHPA was used as extractant. The best extraction conditions were found to be of the molar ratio of D2EHPA and TBP at 2:1 and the equilibrium aqueous pH at 3.50-4.50. D values increased with the increase of the total concentration of TBP and D2EHPA in 1-octanol. Especially, the analysis on the extraction mechanisms clearly indicate(i) TBP in 1-octanol shows negligible reactive extraction toward 4-HP,(ii) D2EHPA in 1-octanol exhibits moderate extraction effect by forming 4-HP:D2EHPA(1:1) and 4-HP:2D2EHPA(1:2) type complexes, while(iii) D2EHPA in TBP/1-octanol demonstrates the maximum distribution ratio with the 4-HP:D2EHPA(1:1) type complex domination. The discussion provides new insights on the mechanism and opens a new way for the intensified extraction of amphoteric organic compounds by using the mixture of multiple extractants in the diluent.

Reactive extraction for intensifying 2-ethylhexyl acrylate synthesis using deep eutectic solvent [Im:2PTSA]

2-Ethylhexyl acrylate(2-EHA)is one of the most widely used acrylates in the polymer industry,which is synthesized via Fisher esterification that is limited by chemical equilibrium.To intensify the esterification process,in this work,reactive extraction concept is proposed,with halogen-free deep eutectic solvent(DES[Im:2PTSA])as dual solvent-catalyst that consists of imidazole(Im)and p-toluenesulfonamide(PTSA).The bifunctional effects of the DES[Im:2PTSA]are evaluated by thermodynamic analysis and experimental study.Favorable phase splitting is verified byσ-potential analysis predicted by COSMO-RS theory,combined with experiments,and the optimal acid-to-alcohol molar ratio is set to 1.2.The esterification kinetics is then experimentally determined and fitted using the molar-based and activity-based pseudo-homogeneous(PH)models,respectively.The activity-based PH model,that considers the bifunctional roles of the DES,proves to be more accurate with small RMSD of 0.0344.The stability of DES after recycling is validated to further confirm the industrial prospects of DES[Im:2PTSA]in 2-EHA production.

Reactive extraction for synthesizing long chain ester butyl hexanoate intensified by deep eutectic solvent

Butyl hexanoate(BuHE)is an important long-chain ester that is widely used in the food,beverage and cosmetic industries.In this work,reactive extraction concept was proposed to intensify the BuHE formation in a biphasic system,in which deep eutectic solvent(DES)comprising 2-methylimidazole(2-MIm)and p-toluenesulfonic acid(PTSA)was used as dual solvent-catalyst.First,the effect of 2-MIm to PTSA molar ratio on esterification was investigated to determine the optimum DES of[2-MIm:2PTSA],which was characterized by FT-IR and TGA.Then,the liquid–liquid equilibrium(LLE)and esterification experiments were carried out to confirm the extraction and catalytic effect of[2-MIm:2PTSA],respectively.Afterwards,the pseudo-homogeneous kinetic model was employed to describe the esterification kinetics.Finally,the intensification mechanism of reactive extraction for BuHE formation was proposed according to the experiments and interaction effect analysis.

Reactive extraction for preparation of hydrogen peroxide under pressure

The preparation of hydrogen peroxide from anthrahydroquinone by reactive extraction was investigated.The integration process of oxidation of anthrahydroquinone by air and extraction of hydrogen peroxide from the organic phase with water was carried out in a sieve plate column under pressure.The conversion of anthrahydroquinone increased with increasing pressure resulting in an increase of hydrogen peroxide concentration in the aqueous phase.However,no change in extraction efficiency of hydrogen peroxide was observed.A mathematical model for gas-liquid-liquid reactive extraction was established.In themodel,the effects of pressure and gas superficial velocity on reaction were considered.With increasing gas superficial velocity,the conversion of anthrahydroquinone increased,and the fraction of hydrogen peroxide extracted reached a plateau with a maximum of 72.94%.However,both the conversion of anthrahydroquinone and the fraction of hydrogen peroxide extracted decreased with increasing organic phase superficial velocity.

Kinetic study on reactive extraction for chiral separation of phenylsuccinic acid enantiomers

The kinetics of the extraction of phenylsuccinic acid(PSA) enantiomers by hydroxypropyl-β-cyclodextrin(HP-β-CD) in a modified Lewis cell was studied,in which HP-β-CD dissolved in 0.1 mol L-1 NaH2PO4/H3PO4 buffer solution(pH = 2.5) was selected as the chiral extractant.PSA enantiomers were extracted from organic phase to aqueous phase in the extraction module.The theory of extraction accompanied by a chemical reaction has been used to obtain the intrinsic kinetics of this extraction module.The different parameters affecting the extraction rate such as agitation speed,interfacial area,initial concentration of PSA enantiomers in organic phase as well as HP-β-CD concentration in aqueous phase were separately studied.The experimental results demonstrate that the extraction reactions are fast.The reactions were found to be first order with respect to PSA and second order with respect to HP-β-CD with forward rate constants of 3.4 × 10-2 m6 mol-2 s-1 for R-PSA and 9.96 × 10?3 m6 mol-2 s-1 for S-PSA.These data will be useful in the design of extraction processes.