Membrane stability and enrichment of nickel in the liquid emulsion membrane process

The parameters affecting the stability of a liquid emulsion membrane (LEM) for enrichment of nickel were studied. The liquid membrane is made up of a carrier (di‐2‐ethylhexylphosphoric acid), organic diluent and an emulsifying agent (sorbitan monooleate). Swelling of the internal phase during extraction results in breakage of the emulsion. The role of pH is very important in the LEM process for extraction of nickel. A significant decrease in swelling was observed by maintaining the pH of the feed phase constant during extraction. A lower osmotic pressure difference between the external and internal phase brings about lower changes in the swelling and membrane breakdown. © 2000 Society of Chemical Industry     

Modeling of the Permeation of Thorium through Liquid Emulsion Membrane

Abstract

A general permeation model for the separation of thorium by liquid emulsion membrane (LEM), using theonyletrichloroacetone HTTA as a carrier is presented. The internal mass transfer in the W/O emulsion drop, the external mass transfer around the drop, the rates of formation, and the decomposition of the complex at the external aqueous‐organic interface were considered. Further, the leakage of the internal aqueous phase to the external phase due to the membrane break‐up is also taken into account. The batch extraction of thorium using HTTA as a carrier was carried out under various experimental conditions. It is found that the extraction rates can be satisfactorily simulated by the proposed model.     

Separation and Concentration of Phenylalanine by Emulsion Liquid Membrane in a CSTR Extraction Process

Abstract

The extraction and concentration of phenylalanine by the continuous CSTR emulsion liquid membrane (ELM) separation process has been evaluated. We discussed the influence of operating conditions on the separation and concentration efficiencies of phenylanine. It was found that the extraction rate of phenylalanine increased as the amount of emulsion used and the internal concentration of H⁺ increased. However, the concentration ratio of phenylalanine increased as the emulsion amount and acid concentration increased only up to a certain limit and then declined with further increases of these. The reduction of the concentration ratio is due to the swelling of the emulsion drops. Two effects, swelling owing to osmotic pressure and swelling caused by the entrainment of water due to mechanical agitation, are responsible for the swelling of emulsion drops. A mass transfer model for analyzing the extraction of phenylalanine by liquid surfactant membrane is presented. The model assumes that the extraction and stripping reactions are reversible, and that the reaction equilibrium exists in both the internal and the external interfaces. The scheme for mass transfer is based on a hollow sphere model. The phenomena of osmotic swelling, mechanical entrainment, and breakage are all considered in the mathematical treatment. The effects of operation parameters on the extraction efficiency and concentration ratio are discussed by simulation.     

乳化液膜提取柠檬酸及其溶胀的研究

本文研究了采用Ｗ／Ｏ型乳化液膜提取水溶液中的柠檬酸，同时研究了柠檬酸提取过程中水的传质行为（乳液溶胀）。考察了表面活性剂、载体、反萃剂Ｎａ２ＣＯ３、柠檬酸浓度对柠檬酸传质和乳液溶胀的影响。实验结果表明：萃取率随载体和内相试剂浓度的增加而增加；当载体和初始柠檬酸浓度较高时，乳液更易于溶胀，由此得出了除渗透压造成的乳液溶胀外，溶质与载体形成的络合物也能促成乳液的溶胀。提出了分离浓缩柠檬酸的最佳乳液配方     

EFFECTS OF THE EMULSIFIER IN COPPER EXTRACTION BY LIX64N-SPAN 80 LIQUID SURFACTANT MEMBRANES

Span 80-LIX65N-LIX63 liquid surfactant membranes (LSMs) were used to extract copper from sulfate solutions at a pH of 2.0. The physico-chemical effects of Span 80 (sorbitan monooleate) were investigated with the aid of measurements of emulsion stability (as determined by leakage of K ions from the internal to the external phase), membrane phase viscosity, emulsion viscosity, and inter-facial tension. As the concentration of Span 80 was increased, copper extraction rate at first increased, rose through a maximum, and then decreased. The initial increase corresponded to a significant improvement in the stability of emulsion globules. Inter-facial tension measurements indicated that in order to achieve stable emulsion globules, a high adsorption density of the emulsi-fier at the emulsion interfaces in a LSM system was needed. It was further shown that a bulk phase emulsifier-extractant interaction at high extractant concentrations had an adverse effect on the stability of emulsion globules by removing emulsifier molecules from the interface. However, the high emulsifier adsorption density required for emulsion stability led to a decrease in the extractant concentration at the interface and therefore reduced the rate of copper complexation at the membrane phase/external phase interface. In addition, the viscosity measurements suggested that the decrease in metal extraction at emulsifier concentrations above the optimum might also be partly a result of the restricted movement of the internal phase droplets, an increase in the inter-facial viscosity, and/or a decrease in the membrane phase/external phase interfacial area.     

Membrane‐liquid emulsion membrane process using a liquid emulsion membrane process using methane sulfonic acid as a strippant

The application of a liquid emulsion membrane (LEM) process in the recovery of zinc from aqueous solutions is discussed. The role of a stripping agent is very important in the LEM extraction process. Various stripping agents, such as hydrochloric, sulfuric, nitric and methane sulfonic acids, were tested for the stability of membrane. Methane sulfonic acid outperforms the other acids as a strippant. Further importance was given to the stability of the liquid emulsion membrane during the extraction process. The important variables affecting the LEM permeation process of zinc in a mechanically agitated contactor (MAC), such as residence time for extraction, speed of agitation, organic diluents, surfactant concentration and internal strip acid concentration, were systematically investigated. Emulsion swelling and breakage that occurred during these investigations were also described. Finally, the static mixer (SM) device was shown to have a very good potential for LEM extraction of zinc as it outperforms MAC.     

Swelling phenomena of emulsion liquid membranes with dithio-DEHPA as carrier

The purpose of this paper is to investigate the swelling of emulsion liquid membranes using dithio-DEHPA as carrier. The application of interest was the removal of zinc from a synthetic aqueous solution which simulates a zinc plant effluent. The effect of several variables such as the concentration of carrier in the membrane, stirring speed and permeation time on the swelling of the emulsion is reported. Experimental results show that occlusion depends mainly on the amount of carrier in the membrane and can be significant when the concentration of carrier is lower than 6.0%. The interfacial tension analysis confirms that the size of globules is influenced by the concentration of carrier in the membrane. Stirring speed and permeation time are related to the water transport and must be kept at low values.     

乳状液膜法提取半胱氨酸的研究

:本文以三辛胺为迁移载体 ,Span80为表面活性剂 ,液体石蜡为膜相添加剂 ,氨基酸料液做外水相建立液膜体系 ,研究不同实验条件下半胱氨酸的迁移情况 ,确定了提取半胱氨酸的适宜条件 ,提取率可达 80 %以上     

PHENOL REMOVAL BY EMULSION LIQUID MEMBRANE: A MODIFIED DIFFUSION MODEL

A diffusion model is developed to simulated the behavior of mass transport of the solute in the emulsion liquid membrane. The solute is allowed to react reversiblely with the internal reagent, and the effective diffusivity of the solute in membrane phase is dependent on local solute concentration in membrane phase. A numerical solution is presented for the non-linear equations of this model. The results are compared with those of two previous models, and it is found that the Modified Diffusion Model represents more accurately than other earlier models.     

Process Intensification via Liquid Emulsion Membrane Technique in Extraction and Enrichment of Rhodium (III) from Chloride Media

A liquid emulsion membrane (LEM) system as a tool for process intensification has been studied for rhodium recovery using di-2-ethylhexylphosphoric acid (D2EHPA) as a metal carrier and Monemul 80 as a surfactant, dissolved in liquid paraffin. The various process parameters affecting the LEM process, such as extractant, surfactant, and strip phase concentrations, the speed of agitation, the batch contact time, and the treat ratio have been experimentally investigated to get better insight into the process. Perchloric acid was found to be a better stripping agent in the LEM process. It was observed that the extraction of Rh (III) can be significantly more in the absence of a water repelling agent. The maximum enrichment of Rh (III) in the internal phase obtained was 4.3 times with feed phase pH adjusted to 6, perchloric acid (1.5 mol/dm³), and contact time of 15 min. A mass transfer model to predict the performance of the LEM system was used and found to fit well with the experimental data.     

Process intensification in extraction by liquid emulsion membrane (LEM) process: A case study; enrichment of ruthenium from lean aqueous solution

Process intensification in extraction as a unit operation can be realized through liquid emulsion membrane (LEM) process by combining extraction and stripping in one stage eliminating the need of stripper. LEM technique is very useful to enrich very lean aqueous phase containing precious metal to aid the recovery process. The technique is illustrated by applying the same to enrich platinum group noble metal, ruthenium (Ru) from its aqueous solution. The liquid membrane phase consisted of extractant (trioctylamine) dissolved in liquid paraffin modified with 1-octanol and the surfactant used was Monemul 80. The strip phase found to be very effective was perchloric acid. To facilitate extraction tin(II) chloride was added to the aqueous feed phase containing Ru at 20 ppm level. Various process parameters affecting the performance of LEM process such as extractant, surfactant, strip phase concentrations, the batch extraction time, the treat ratio and the speed of agitation were studied at bench scale to aid process development.     

Studies of extraction of methylene blue from synthetic waste water using liquid emulsion membrane technology

A comprehensive study pertaining to liquid emulsion membrane (LEM) extraction process of methylene blue from wastewater is presented. The liquid membrane is made of an emulsifying agent (Monumal 80) with various organic diluents. Surfactant (5 wt%) (Monumal 80) and kerosene gave good extraction. Important variables affecting LEM permeation process include stability of membrane, contact time of extraction, strip phase concentration, treat ratio (strip phase: organic phase), stirring speed, feed phase concentration were systematically studied for percentage of extraction by LEM. Kerosene as diluent gave 99.57% extraction with NaOH as strip phase. © 2012 Canadian Society for Chemical Engineering     

液体表面活性剂膜的传质模型

本文提出了一个新的关于液膜传质的模型.该模型不仅考虑了溶质在乳状液球内核中的渗透过程,还考虑了由表面活性剂所致的界面阻力升高效应,因而更加准确地描述了液膜体系的传质过程.该模型的另一个特点是考虑了在传质过程中膜的破裂,从而使数学模型更加迫近液膜体系的实际情况.实验结果与理论分析均表明,溶质透过乳状液外围的表面活性剂薄层的分子扩散是整个液膜传质过程的速率控制段.这一结论将导致对液膜结构更加深刻的理解,并将有助于液膜体系的改进.     

W/O/W乳液的渗透溶胀

<正>W/O/W或/O/W/O多重乳状液是一种复分散体系.早在1925年它就被人们所发现.直到最近,由上人们发现它可广泛用于液膜分离技术、固定化酶、体内解毒以及控制释放等领域,因而对多重乳状液的研究工作越来越受到重视.对于乳液溶胀,至今尚未有过系统的研究报道.根据分析及实验结果,溶胀是由渗透与夹带两个因素引起的.本文建立了W/O/W乳液的渗透溶胀模型,并通过实验研究了影响溶胀的因素.     

表面活性剂液膜萃取过程的乳液溶胀(Ⅱ)——乳液溶胀的抑制

探讨了抑制乳液溶胀的途径。着重研究了迄今尚未充分讨论的外水溶质对乳液溶胀的影响。结果证实,外水相中的电解质或葡萄糖能抑制夹带溶胀,并使渗透溶胀率降低。研究了溶剂和温度对溶胀的影响。提出了计算渗透溶胀的修正数学模型,计算值与实验值相符。     

乳状液膜在湿法磷酸体系中稳定性的研究

研究了以N205为表面活性剂,磺酸基络合剂为流动载体,液体石蜡为膜增强剂,磺化煤油为膜溶剂,盐酸加氯化钠为内水相的乳状液膜在湿法磷酸体系中捕获镁离子时的稳定性。结果表明,表面活性剂用量、内水相反萃剂浓度、萃取时间、萃取转速等对液膜的稳定性均有显著影响。在一定的范围内,随着表面活性剂用量的增加,液膜的稳定性增加。适宜的操作条件为:在1 000 r/min下加内水相,3 000 r/min下制乳15 min,萃取转速为200 r/min。     

AMINE PHASE PARTITIONING USING EMULSION LIQUID MEMBRANES

The bulk phase solute partition coefficient (K_mb) is an important parameter in the modeling studies of emulsion liquid membrane (ELM) extraction systems, since it gives the ratio of solute concentration in the membrane phase to the solute concentration in the bulk phase at equilibrium. The partitioning of aromatic amines (aniline, p-toluidine, m-toluidine. and 4-chloroaniline) in water-oil-water type ELM systems has been studied experimentally as a function of internal phase volume fraction in the emulsion. Because aqueous aromatic amine solutions (AAASs) are known to photooxidatively decompose under the effect of light, mixing, and aeration which are present in the partitioning experiments conducted in this study, the amount of decrease in the bulk phase amine concentration due to photooxidation needs to be determined. In the partitioning experiments, the equilibrium was reached in the first 5-10 minutes after the emulsion addition to the AAASs. It was found that the photooxidative decomposition of the AAASs in this 5-10 minute-period was so small that neglecting the photooxidation effects introduced virtually no error in the K_mb calculations. Approximately constant values of K_mb were obtained from the partitioning experiments for each of the four aromatic amines at different internal phase volume fraction to membrane phase volume fraction ratios ([(1 - ƒ_m/ƒ_m]) in the emulsion. The magnitude of the surface area betwen the internal phase and membrane phase was found to have no effect on the partitioning of the aromatic amines for the ELM systems studied here.     

表面活性剂液膜萃取过程的乳液溶胀(Ⅰ)——载体对乳液溶胀的影响

研究了载体对乳液溶胀的影响。发现膜相中存在载体时使界面张力降低,说明载体能吸附于界面。表面活性剂和载体在界面的竞争吸附是影响乳液溶胀的关键因素。本研究表明,液膜的夹带溶胀随膜相中载体浓度的增大而减小,而渗透溶胀则随之而加剧。提出了估算溶胀率的修正方程,用修正方程对膜相存在载体时的乳液夹带溶胀率进行了估算,计算值与实验数据吻合良好。