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 pho...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.展开更多
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 proce...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.展开更多
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 biphasi...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.展开更多
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 organ...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.展开更多
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 so...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.展开更多
The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hyd...The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aqueous solution containing a reactive extractant, like borate salts, borate complexes, a monosalt of dicarboxylic acid, hydroxypropyl-cyclodextrins, and silver nitrate, shows limited potential to be used. Another approach, in which the alcohol is chemically modified prior to the extraction into an easy-extractable form, in this case a monoester/carboxylic acid, shows much more potential. An environmentally benign aqueous solution of sodium hydrogen carbonate can provide a distribution ratio of benzyl alcohol up to 200, leaving the solubility of the organic solvent in the aqueous solution unchanged relative to pure water and therefore increasing the selectivity with two orders of magnitude. The modification of aromatic, cyclo-aliphatic, and linear aliphatic alcohols can be performed efficiently in the apolar organic solvent without need for a catalyst. The recovery of the modified alcohol can be performed by back-extraction in combination with a spontaneous hydrolysis.展开更多
Extraction of chromate ions from wastewater by tri alkylamine(R 3N) dissolved in kerosene was studied at 2560℃. 1 Octanol was used as the modifier to remove the third phase. The aqueous phase was a sulfuric acid...Extraction of chromate ions from wastewater by tri alkylamine(R 3N) dissolved in kerosene was studied at 2560℃. 1 Octanol was used as the modifier to remove the third phase. The aqueous phase was a sulfuric acid solution of Cr(Ⅵ) in the concentration range commonly encountered in the galvanizing industry, namely about 2.0 mol/L. Measurement of equilibrium behavior of Cr(Ⅵ) was carried out over wide concentration ranges of amine, Cr 2O 2- 7 and 1 octanol. Experimental results showed that the proper temperatures for extraction are 2540℃ , the [H +] of the aqueous phase is 2 mol/L, and the solvent composition is 30% R 3N, 64% kerosene, and 6% 1 octanol. Prediction and optimization of solvent extraction plant performance for variable industrial feed conditions are then possible. The influence of 1 octanol as the modifier to remove the third phase was also studied.展开更多
Tertiary amines dissolved in diluents are attractive extractants for recovery of carboxylic acids from dilute aqueous solutions. Quantitative Fourier transform infrared (FTIR) analysis of organic solutions containin...Tertiary amines dissolved in diluents are attractive extractants for recovery of carboxylic acids from dilute aqueous solutions. Quantitative Fourier transform infrared (FTIR) analysis of organic solutions containing various concentrations of trioctylamine (TOA), n octanol, and propionic acid was carried out, and liquid liquid equilibrium was investigated using TOA in n octanol as the solvent. The fraction of ion pair association between TOA and propionic acid in the organic phase was quantitatively determined by FTIR. The apparent reactive extraction equilibrium constant, K 11 , was calculated using the quantitative FTIR spectrum and the equilibrium data. The results show that the fraction of ion pair association depends on diluent concentration, complex dissolution for propionic acid, and association between TOA and propionic acid. The K 11 based on quantitative FTIR has the same loading trend as that from the equilibrium data.展开更多
With Nb-Ti-stabilized 430 ferritic stainless steel(NTS430FSS) and SUS 430 ferritic stainless steel(SUS430FSS) as experimental materials, the influence of precipitation on intergranular corrosion resistance was inv...With Nb-Ti-stabilized 430 ferritic stainless steel(NTS430FSS) and SUS 430 ferritic stainless steel(SUS430FSS) as experimental materials, the influence of precipitation on intergranular corrosion resistance was investigated. A series of aging treatment were carried out. The free-exposure corrosion test and double loop electrochemical potentiokinetic reactivation(DL-EPR) test with a scan rate of 1.67 m V/s at 26 °C were applied to evaluate the intergranular corrosion(IGC) resistance. Metallographic observation, scanning electron microscope(SEM), transmission electron microscope(TEM) with energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD) analysis were conducted. The results show that IGC occurred in SUS430 FSS aged above 700 °C, while it occurred in NTS430 FSS as the temperature was improved to 1 050 °C. The critical degree of sensitization Ir/Ia reaches 0.305 in SUS430 FSS, which is higher than that of NTS430 FSS, i.e. 0.010, aged at 950 °C for 2 h. The TEM, EDS and XRD results show that a large amount of Cr23C6 precipitates with size of 60 nm×22 nm are located at the SUS430 FSS grain boundaries as chains. With the addition of Nb and Ti and reduction of C, the amount of precipitates reduces significantly in NTS430 FSS. A majority of Cr23C6 were replaced by Ti C and Nb C. Only a small amount of spherical Ti C(R=186 nm) and square Ti N(312 nm×192 nm) with Nb and Cr adsorbed are left along grain boundaries. Due to the dual stabilization of Nb and Ti, the precipitation of Cr23C6 is restrained, the chromium depleted region is avoided and accordingly the resistance to the intergranular corrosion is improved.展开更多
基金supported by the Science and Technology Research Project of Henan Province (192102310490 and 212102310505)。
文摘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.
基金The financial support from National Natural Science Foundation of China(21776074,21861132019 and 21978096)is greatly acknowledged
文摘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.
基金support from National Natural Science Foundation of China(21776074 and 21576081)is greatly acknowledged.
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China (20976041)Program for New Century Excellent Talents in University,Hunan Provincial Natural Science Foundation of China (10JJ1004)the Open Fund Project of Key Laboratory in Hunan University (09K095)
文摘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.
基金Supported by DSM, NWO-CW (Netherlands Organisation for Scien-tific Research-Chemical Science) and NOVEM (Netherlands Agency for Energy and Environment)
文摘The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aqueous solution containing a reactive extractant, like borate salts, borate complexes, a monosalt of dicarboxylic acid, hydroxypropyl-cyclodextrins, and silver nitrate, shows limited potential to be used. Another approach, in which the alcohol is chemically modified prior to the extraction into an easy-extractable form, in this case a monoester/carboxylic acid, shows much more potential. An environmentally benign aqueous solution of sodium hydrogen carbonate can provide a distribution ratio of benzyl alcohol up to 200, leaving the solubility of the organic solvent in the aqueous solution unchanged relative to pure water and therefore increasing the selectivity with two orders of magnitude. The modification of aromatic, cyclo-aliphatic, and linear aliphatic alcohols can be performed efficiently in the apolar organic solvent without need for a catalyst. The recovery of the modified alcohol can be performed by back-extraction in combination with a spontaneous hydrolysis.
基金the National Natural Science Foundationof China(No.2 9836 130
文摘Extraction of chromate ions from wastewater by tri alkylamine(R 3N) dissolved in kerosene was studied at 2560℃. 1 Octanol was used as the modifier to remove the third phase. The aqueous phase was a sulfuric acid solution of Cr(Ⅵ) in the concentration range commonly encountered in the galvanizing industry, namely about 2.0 mol/L. Measurement of equilibrium behavior of Cr(Ⅵ) was carried out over wide concentration ranges of amine, Cr 2O 2- 7 and 1 octanol. Experimental results showed that the proper temperatures for extraction are 2540℃ , the [H +] of the aqueous phase is 2 mol/L, and the solvent composition is 30% R 3N, 64% kerosene, and 6% 1 octanol. Prediction and optimization of solvent extraction plant performance for variable industrial feed conditions are then possible. The influence of 1 octanol as the modifier to remove the third phase was also studied.
基金the National Natural Science Foundationof China(No. 2 9836 130 )
文摘Tertiary amines dissolved in diluents are attractive extractants for recovery of carboxylic acids from dilute aqueous solutions. Quantitative Fourier transform infrared (FTIR) analysis of organic solutions containing various concentrations of trioctylamine (TOA), n octanol, and propionic acid was carried out, and liquid liquid equilibrium was investigated using TOA in n octanol as the solvent. The fraction of ion pair association between TOA and propionic acid in the organic phase was quantitatively determined by FTIR. The apparent reactive extraction equilibrium constant, K 11 , was calculated using the quantitative FTIR spectrum and the equilibrium data. The results show that the fraction of ion pair association depends on diluent concentration, complex dissolution for propionic acid, and association between TOA and propionic acid. The K 11 based on quantitative FTIR has the same loading trend as that from the equilibrium data.
文摘With Nb-Ti-stabilized 430 ferritic stainless steel(NTS430FSS) and SUS 430 ferritic stainless steel(SUS430FSS) as experimental materials, the influence of precipitation on intergranular corrosion resistance was investigated. A series of aging treatment were carried out. The free-exposure corrosion test and double loop electrochemical potentiokinetic reactivation(DL-EPR) test with a scan rate of 1.67 m V/s at 26 °C were applied to evaluate the intergranular corrosion(IGC) resistance. Metallographic observation, scanning electron microscope(SEM), transmission electron microscope(TEM) with energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD) analysis were conducted. The results show that IGC occurred in SUS430 FSS aged above 700 °C, while it occurred in NTS430 FSS as the temperature was improved to 1 050 °C. The critical degree of sensitization Ir/Ia reaches 0.305 in SUS430 FSS, which is higher than that of NTS430 FSS, i.e. 0.010, aged at 950 °C for 2 h. The TEM, EDS and XRD results show that a large amount of Cr23C6 precipitates with size of 60 nm×22 nm are located at the SUS430 FSS grain boundaries as chains. With the addition of Nb and Ti and reduction of C, the amount of precipitates reduces significantly in NTS430 FSS. A majority of Cr23C6 were replaced by Ti C and Nb C. Only a small amount of spherical Ti C(R=186 nm) and square Ti N(312 nm×192 nm) with Nb and Cr adsorbed are left along grain boundaries. Due to the dual stabilization of Nb and Ti, the precipitation of Cr23C6 is restrained, the chromium depleted region is avoided and accordingly the resistance to the intergranular corrosion is improved.