Removal of iron from Cr-electroplating solution by extraction with di(2-ethylhexyl)phosphoric acid in kerosene

The extraction of iron(III) from aqueous sulphate solution was studied using di(2-ethylhexyl)phosphoric acid (HA) mixed with kerosene. Distribution ratios were investigated as a function of the concentration of sulphuric acid, extractant, metal, hydrogen ion as well as the phase ratio and loading capacity of the extractant. The extracted iron species was suggested as [Fe(HA₂)₃] and the extraction constant was found to equal (9.1 ± 0.5) × 10². The thermodynamic functions calculated from the temperature dependence data referred to the endothermic nature of the extraction process. The method of extraction was successfully applied to remove the iron from the chromium electroplating solution giving purification percent of about 97.5%.     

Extraction of L-synephrine by Bis(2-ethylhexyl)phosphoric acid/n-octanol Reversed Micelles

In this study, reversed micelles of Bis(2-ethylhexyl)phosphoric acid/n-octanol was prepared to investigate the purification of L-synephrine in Citrus aurantium fruit crude extract. The reverse micellar system formed was confirmed with atomic force microscopy and the effect of important factors on extraction efficiency, such as the pH of the aqueous phase, molar ratio of water to surfactant, surfactant concentration, cationic ion concentration, and extraction time, was studied. Under the optimal operational conditions, the purity of L-synephrine was improved to be >85% and the total yield >98%. Mathematic analysis and experimental results exhibited that the extraction process in this system was effectuated mainly via electrostatic interactions between L-synephrine and the surfactant.     

二（2-乙基已基）磷酸萃取氨基苯甲酸的平衡特性

A series of extraction equilibrium experiments for aminobenzoic acid with di(2-ethylhexyl)phosphoric acid (D2EHPA) dissolved in n-octane or 1-octanol was carried out. The effects of aminobenzoic acid concentration,D2EHPA concentration and pH on the distribution ratio were discussed in detail. The infrared spectra of the organic phase loaded with solute illustrated that pH had little effect on the structure of the complex formed. There proceed ion association and cation-exchange.reaction in the extraction. An expression of the equilibrium distribution was proposed.     

Extraction of zinc(II) from ammoniacal solution into hydrophobic ionic liquids

BACKGROUND: Separation and recovery of zinc from ammoniacal solutions with solvent extraction is very important in the hydrometallurgical industry. Ionic liquids (ILs) have considerable potential for the separation of metal ions. The extraction behaviour of zinc from ammoniacal solution into three hydrophobic ILs was investigated using β‐diketone as the extractant. RESULTS: The extraction efficiency of zinc for three ILs reached a maximum at pH 7.5 and subsequently decreased with increase of pH and it also decreases with increase of the total ammonia concentration. The overall extraction process is exothermic. The extractability decreases in the IL order: [BMIM]NTf₂ > [OMIM]PF₆ > [OMIM]NTf₂. The results of X‐ray absorption spectra indicate that the coordination number of the extracted zinc complexes decreases with increase in the hydrophobicity of the ILs. The results of five recycling experiments indicate that the three hydrophobic ILs are more stable than [BMIM]PF₆ for the extraction of zinc in ammoniacal solutions. CONCLUSION: Hydrophobic ILs combined with β‐diketone can be used to extract zinc from ammoniacal solutions. The extraction of zinc is dependent on the zinc species in ammoniacal solutions and the hydrophobicity of ILs. Moreover, the latter affects both the extractability of extraction systems and the structure of the extracted complexes. © 2012 Society of Chemical Industry     

Extraction of uranium (VI) by di-(2-ethylhexyl)phosphoric acid gels based on a styrene-divinylbenzene copolymer

Uranium (VI) can be efficiently extracted using hydrophobic gel particles prepared by swelling styrene-divinylbenzene copolymer beads with di-(2-ethylhexyl)phosphoric acid packed into columns. Retained U (VI) can be quantitatively eluted with acid solutions. The effects of incorporating different organic solvents into the gel on its capacity and performance have been investigated. It was found that nitrobenzene gave the best results. The conditions required for the preparation of gels of high capacity have been established.     

Functionalized chitosan with butylammonium ionic liquids for removal of Cr(VI) from aqueous solution

Environmental pollution by heavy metals is currently a problem of great concern for human health. In this context, this study aims to contribute with the synthesis and characterization of chitosan functionalized with three different ionic liquids (n-butylammonium acetate, sec-butylammonium acetate, and tert-butylammonium acetate) followed by its application in hexavalent chromium effluent treatment. The adsorbents synthesized (ChN, ChS, and ChT) were characterized by SEM, EDS, FTIR, BET, RDD, PSD, and XRD techniques. Afterward, the influences of temperature, contact time, and pH on the Cr(VI) adsorption process were evaluated. The solution with pH 3 displayed the highest adsorption capacities (107.31, 104.60, and 107.97 mg.g^-1 for ChN, ChS, and ChT, respectively). The kinetic data were better adjusted to the Weber-Morris kinetic model with an ideal time of 2 h. Furthermore, the influence of temperature was evaluated using the Freundlich and Langmuir isotherms, with maximum capacities of 142.05 (ChN), 131.58 (ChS), and 146.63 mg.g^-1 (ChT). The adsorbent displayed enhanced adsorption properties in comparison with raw chitosan by an intensification of the electrostatic interaction between amino groups and hexavalent chromium. Finally, the reusability was investigated, and significant results were observed (84.33 ± 4.87%) in the adsorption process after 4 cycles.     

Extraction behaviour of dioxouranium(VI) cation by two phosphorous-based liquid cation-exchangers in room-temperature ionic liquids

Extraction of uranium with bis-(2-ethylhexyl) phosphonic acid (PC-88A) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex-272) was studied in several imidazolium-based room-temperature ionic liquids (RTILs), C_nmim·X (where n = 4, 6, 8 and X = PF₆ and Tf₂N). The extraction kinetics was slow and about 0.5–1 h equilibration time was required for most of the extraction systems, except in C₈mim·PF₆, where 2 h and 4 h were required to reach the equilibrium values for PC-88A and Cyanex-272, respectively. The extraction of UO₂²⁺ ion by the two ligands was significantly affected by the nature and the composition of the RTILs.     

Synthesis and identification of bis (diacylglycero) phosphoric acid and bis (monoacylglycero) phosphoric acid

Synthesis of bis-(diacylglycero)phosphoric acid fromsn-1,2-dipalmitoylglycerol and phenylphosphoryl dichloride according to Baer (1) was revised. New data are reported about identification of the intermediate and final products: (a) bis-phosphatidic acid phenyl ester is very slowly visualized by the Zinzade reagent and can escape notice; (b) large amounts of phosphatidic acid chloride phenyl ester are also formed; and (c) very little transacylation fromsn-1,2-dipalmitoyl-glycerol to the 1,3-isomer is observed. Hydrolysis of bis-phosphatidic acid to bis-lysophosphatidic acid is much easier using phospholipase A₂ from pig pancreas than from snake or bee venom.     

Extraction of Fe(III) from phosphoric acid by HDDNSA

A study was conducted on the stoichiometry of the reaction that takes place on the extraction of ferric ions by didodecyl naphthalene sulphonic acid (HDDNSA) from phosphoric acid solutions. The experimental results were numerically analyzed by nonlinear regression. It was found that ferric forms two compounds with HDDNSA, namely Fe(DDNSA)₃, and FeHPO₄-DDNSA. The values of the equilibrium constants of the reactions involved were also calculated.     

功能化离子液体在室温下催化醛(酮)与二元醇的缩合反应

采用功能化离子液体1-甲基-3-丙磺酸基咪唑盐作为溶剂/催化剂双功能体系,通过探针反应,固定原料环己酮与离子液体催化剂的摩尔比为50∶1进行工艺参数的优化,得到优化工艺条件为:n(环己酮)∶n(1,2-丙二醇)=1∶1.5,在20℃条件下反应0.1 h可以得到缩合产物,转化率大于97%.研究了该催化剂对其他醛(酮)与二元醇的缩合反应的催化性能,结果表明,该工艺无需有机溶剂及脱水剂,反应结束产物与催化体系分层,通过倾析便可得到产物,简化了分离过程且离子液体可以循环使用.     

Equilibrium studies of the extraction of zirconium(IV) from sulfuric acid solutions with Di(2-ethylhexyl)phosphoric acid

Equilibrium studies were made at 25°C in the extraction of zirconium(IV) from sulfuric acid solutions with di(2-ethylhexyl)phosphoric acid (D2EHPA, HR) dissolved in kerosene. The reaction stoichiometry was numerically determined and the compositions of the extracted species were found to be ZrR₄ and ZrR₄(HR) at low loading ratios of D2EHPA (α < 0.09), but became ZrR₄ and ZrR₄(HR)₃ at relatively higher loading ratios (0.10 < α < 0.32). The equilibrium constants for the formation of these species were also obtained. Furthermore, numerical treatment of the experimental data excluded the existence of polynuclear complexes under the conditions studied (α < 0.32).     

二(2-乙基己基)磷酸萃取氨基苯甲酸的相平衡分配系数

络合萃取法分离极性有机物稀溶液具有高效性和高选择性,本文以二（２－乙基已基）磷酸（Ｄ２ＥＨＰＡ）为络合剂;正辛烷或正辛醇为稀释剂,在不同的ＰＨ值条件下实验测定了氨基苯甲酸稀溶液的萃取相分配系数,讨论了影响因素,分析了萃合物的组成。提出了平衡分配系数的关系式。     

氨基酸离子液体-MDEA混合水溶液的CO_2吸收性能

为改善N-甲基二乙醇胺(MDEA)水溶液对CO2气体的吸收性能,选择了四甲基铵甘氨酸([N1111][Gly])、四乙基铵甘氨酸([N2222][Gly])、四甲基铵赖氨酸([N1111][Lys])、四乙基铵赖氨酸([N2222][Lys])4种功能性离子液体作为活化剂与其复配组成新型CO2吸收剂。用恒定容积法考察了总质量分数为30%的混合溶液吸收CO2的性能,分析了离子液体在水溶液中与MDEA通过质子传递相互促进吸收CO2的机理。实验结果显示离子液体能够显著提高MDEA水溶液吸收CO2的速率,且吸收速率随着添加量的增加而提高。在本文所用的几种混合吸收剂中,阴离子为赖氨酸的离子液体混合吸收剂具有较高的吸收负荷;而[N1111][Gly]-MDEA混合溶液对CO2的初期吸收速率最快,同时[N1111][Gly]-MDEA混合吸收剂的再生效率高于其他离子液体混合吸收剂,达到98%。     

Extraction of reactive dyes from aqueous solutions by halogen‐free ionic liquids

Dyes are commonly used in various industries and unfortunately many of them are discharged into water bodies, causing environmental problems. In the current study, three hydrophobic, halogen‐free ionic liquids were synthesised and their capability as extracting agents was evaluated using four reactive dyes (CI Reactive Blue 4, CI Reactive Black 5, CI Reactive Orange 16 and CI Reactive Red 2). The ionic liquids, immiscible with the aqueous phase, could extract the reactive dyes from aqueous solutions, withdrawing the same amount of weight. The effects of pH and temperature on the extraction process were also studied. Trioctylmethyl ammonium ethylenediaminetetraacetate displayed a high extraction efficiency (99%), where only 33 mg of ionic liquids extracted 50 mg of CI Reactive Blue 4. Fourier Transform–infrared spectroscopy was used to screen the interaction between the ionic liquid and CI Reactive Blue 4 during the extraction stage.     

Soybean hull functionalized by phosphoric acid for sorption of copper from aqueous solution

One kind of potentially biodegradable cationic sorbent, which bears hydroxyl groups of phosphoric acid as its functional groups, with high sorption capacity of copper was prepared by thermochemically esterifying phosphoric acid (PA) onto soybean hull. Sorption of Cu(II) from aqueous solution onto modified soybean hull (MSH) was investigated in a batch system. The sorption experiments were performed under various conditions such as different initial pH, copper concentration, MSH dosage, and contact time. The maximum copper sorption was obtained when initial solution pH≥3.5. The isothermal data of copper sorption fitted the Langmuir model and the sorption process could be described by the pseudo-first-order kinetic model. The maximum sorption capacity (Q _m ) of MSH for Cu(II) was 31.55 mg/g. For 100 mg/l of Cu(II) solution, a sorption ratio above 91% could be achieved by 5.0 g/l of MSH. The equilibrium of Cu(II) sorption was reached within 50 min. The foreign cation and chelator in Cu(II) solution caused decline of Cu(II) sorption.     

Adsorption equilibrium,kinetics, and dynamic separation of Ca2+ and Mg2+ ions from phosphoric acid-nitric acid aqueous solution by strong acid cation resin

The separation of Ca²⁺ and Mg²⁺ ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer. This paper studied the adsorption equilibrium, kinetics, and dynamic separation of Ca²⁺ and Mg²⁺ ions by strong acid cation resin, and the effects of phosphoric acid and nitric acid on the adsorption process were investigated. The results reveal that the adsorption process of Ca²⁺ and Mg²⁺ ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g^-1 and 1.83 mmol·g^-1, respectively. The adsorption kinetics of Ca²⁺ and Mg²⁺ ions on resin fits better with the pseudo-first-order model, and the adsorption equilibrium in pure water is reached within 10 min contact time, while at the present of phosphoric acid, the adsorption rate of Ca²⁺ and Mg²⁺ ions on resin will go down. The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution, but the dynamic operation should control the flow rate of mix acid solution. Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.     

Solvent extraction of lanthanum and cerium ions from hydrochloric acidic aqueous solutions using partly saponified 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester

In order to clarify the extraction process with saponified extractant, the solvent extraction experiments of rare earth elements(REEs), lanthanum and cerium, by using partly saponified 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester(EHEHPA, HL) from hydrochloric acidic solutions have been performed. The concentration of initial aqueous rare earth ion was in a range of 0.0010–0.1000 mol·L~(-1); EHEHPA in a range of 0.2877–0.8631 mol·L~(-1) with saponification rate of 0.3(mole fraction), and the initial aqueous p H in a range of 1.00–4.00. Firstly, the extracted species were determined by the saturation extraction capacity method. Secondly, according to the equilibrium aqueous pH values, the extraction processes were divided into three different categories: extraction with saponified EHEHPA, extraction with un-saponified EHEHPA, and hydrolysis process. Finally, for the first two processes, in order to predict the distribution ratio, two semi-empirical calculation models were developed with.The calculation results are in good agreement well with the experimental data.     

Recovery of ionic liquids from dilute aqueous solutions by electrodialysis

Ionic liquid/s (IL/ILs) are ideal solvents for many separation processes, such as cellulose dissolution, extraction of heavy metal ions and coal liquefaction residues, etc. During the above processes, ILs would inevitably remain in effluents. Due to their high costs and potential detrimental impacts on environment, it is extremely important to recycle ILs from dilute aqueous solutions. Electrodialysis (ED) was used for primary separation and recycling ILs. In order to evaluate the performance of ED process, the effects of initial concentration, applied voltage and initial volume of the dilute solutions on the overall current efficiency (η), recovery ratio (R) and concentration ratio (ω) were investigated. Among these experimental results, the highest recovery ratio could reach 85.2% and the highest overall current efficiency could reach 80.9%. The ED energy consumption is also discussed and the highest specific energy consumption (R_e) could reach about 1350 g/kW h. The effects of IL cation and anion sizes on concentrating process are also evaluated. The experimental results indicate that ED is an effective method to concentrate IL aqueous solutions.     

Adsorption of ionic liquids from aqueous effluents by activated carbon

The separation of imidazolium-based ionic liquids (ILs) from aqueous solution by adsorption has been investigated using a commercial activated carbon (AC) as adsorbent. Equilibrium experiments were carried out for obtaining the adsorption isotherms of ILs on AC at different temperatures. The influence of both cation and anion was analyzed by studying 17 different ILs. The role of the surface chemistry of the adsorbent was also examined using ACs modified by oxidative and thermal treatments. The incorporation of IL on the AC surface was studied by N₂ adsorption-desorption measurements and elemental analysis. In addition to this, a COSMO-RS computational approach was developed to estimate molecular and thermodynamic properties of the solvent-adsorbate-adsorbent system, which allowed us to analyze the adsorption mechanism from a molecular point of view. The results of this work indicate that the adsorption with AC is an affordable environmental application to remove hydrophobic ILs from water streams, proposing the use of acetone for adsorbent regeneration. It has also been demonstrated that the adsorption of refractory hydrophilic ILs can be improved by modifying the amount and nature of oxygen groups on the AC surface, particularly by including hydroxyl groups to promote hydrogen-bonding interactions with the basic groups of hydrophilic ILs.