Liquid Membrane Type Research Articles

Membrane transport of rare earth metal ions N, N’-bisdioctylphosphorylmethyl-1,4-diaminobutane by the active transport mechanism

The method of membrane extraction for rare earth elements (REE) using the carrier N, N’-bisdioctylphosphorylmethyl-1,4-diaminobutane (DPDA-8) ions, leveraging an active transport mechanism, has been optimized. The distribution of DPDA-8 within the membrane pores was confirmed using scanning electron microscopy (SEM). Both light and heavy REE extractions from a simulated solution using DPDA-8 and trioctylphosphine oxide (TOPO) in 1,2-dichlorobenzene were explored. The influence of feed solution pH, carrier and anion concentration, supported liquid membrane (SLM) type and stability, and cell temperature, among other parameters, were meticulously examined. The results indicate a decrease in permeability with a decrease in feed solution pH attributed to competitive acid transport through the membrane. Additionally, the formation of H-complexes between carriers and perchloric or phosphoric acids was investigated using Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. Changes in the stretching bands of amino and phosphine oxide groups in DPDA-8 were monitored and characterized. XRD analysis of the crystal structures of salts DPDA-6·ClO4 and DPDA-12·H2PO4 revealed a two-dimensional layered supramolecular organization with varying anion positions relative to hydrophobic fragments. The DPDA-8 carrier demonstrated significantly higher permeability values compared to TOPO, with differences in permeability exceeding twofold for certain metals. FTIR spectroscopy identified the main coordination centers of DPDA-8 during the liquid–liquid extraction of specific REEs.

In-situ Cu mesh growth of reusable OVs-WO3/CuO heterojunction photocatalysts for enhanced nitrogen fixation efficiency

The loaded photocatalyst is an ideal material for nitrogen fixation, which does not have the problem of secondary pollution caused by powdered catalysts, and has the advantages of uniform distribution, high efficiency and easy recovery. In this paper, CuO and WO3 were grown on copper mesh (CM) by in-situ etching and solvothermal method. The photogenerated carriers and light absorption properties were synergistically promoted with the help of oxygen vacancies and S-type heterojunctions. Under simulated visible-light conditions, a liquid-membrane type reaction was employed and the nitrogen fixation performance was significantly improved. The optimal ammonia production rate of WO3/CuO/CM was 3.878 × 10−2 μmol/cm2/h, which was 9.37 and 5.16 times higher than WO3/CM and CuO/CM, respectively. This study provides ideas for the design of recyclable heterojunction catalysts with oxygen vacancies.

The Latest Achievements of Liquid Membranes for Rare Earth Elements Recovery from Aqueous Solutions-A Mini Review.

The systematic increase in the use of rare earth elements (REEs) in various technologically advanced products around the world (e.g., in electronic devices), the growing amount of waste generated by the use of high-tech materials, and the limited resources of naturally occurring REE ores resulted in an intensive search for effective and environmentally safe methods for recovering these elements. Among these methods, techniques based on the application of various types of liquid membranes (LMs) play an important role, primarily due to their high efficiency, the simplicity of membrane formation and use, the utilization of only small amounts of environmentally hazardous reagents, and the possibility of simultaneous extraction and back-extraction and reusing the membranes after regeneration. However, because both primary and secondary sources (e.g., waste) of REEs are usually complex and contain a wide variety of components, and the selectivity and efficiency of LMs depend on many factors (e.g., the composition and form of the membrane, nature of the recovered ions, composition of the feed and stripping phases, etc.), new membranes are being developed that are "tailored" to the properties of the recovered rare earth elements and to the character of the solution in which they occur. This review describes the latest achievements (since 2019) related to the recovery of a range of REEs with the use of various liquid membranes (supported liquid membranes (SLMs), emulsion liquid membranes (ELMs), and polymer inclusion membranes (PIMs)), with particular emphasis on methods that fall within the trend of eco-friendly solutions.

Short review on liquid membrane technology and their applications in biochemical engineering

As a branch of membrane separation technology, liquid membrane has attracted great attention and expanded investigations in biological chemical engineering, with life and health concern in ecosystems. Composed of membrane solvent and mobile carrier, liquid membrane was acquired of function, performing the facilitated mass transfer across the diffusive solvent, so as for the separation and delivery achievement with efficacy. In this review, two types of liquid membrane are mainly focused, respectively on supported liquid membrane (SLM) of membrane solvent supporter in necessity, and on emulsion liquid membrane (ELM) of the required interfacial stabilizers and homogenization. Accordingly, the transfer mechanism, compositions, structure and features of SLM and ELM are introduced respectively. Moreover, the current investigations of liquid membrane have been discussed, focusing on the improvements of efficacy and stability in separation & detection, encapsulation and delivery, so as to scale up the favorable and efficient application with bio-life concern. Prospectively, this review could provide comprehensive insight into the bio-applications of liquid membrane, and guidelines for the further investigations on the efficacy and long-term applicable stability, in order to realize the industrialization.

Innovative water-based dynamic liquid bubble membrane generation device for gas/vapour separation

Gas and vapour separation by membrane technology has become a promising method because of its high energy efficiency and low capital investment. Here, we demonstrate a proof of concept of the design of a new type of liquid membrane called the “dynamic liquid bubble membrane” (DLBM) connected by plateau borders. The DLBM is composed of a network of bubbles formed by passing a gaseous mixture through water containing a surfactant. The bubble network serves as a membrane to selectively separate the gases/vapours of mixtures according to the different solubilities of the gases in the bubble liquid. To the best of our knowledge, this type of liquid foam has not been described previously. The effects of key experimental factors, such as the surfactant concentration in the water of the membrane solution and the bubble velocity (controlled by the slope of the device) of the DLBM, on the CO2/CH4 separation performance were investigated. The retentate gas (CH4) remained over 99.9 % for the high CH4 concentration injection mixture (>66.7 % CH4). Then, O2/CO2 was used to simulate the fluid of the alveolar lining during the full in-breath process. We found that carbon dioxide transferred outside the bubble film, while oxygen was retained inside the bubble. This finding supports a further understanding of the CO2 transport mechanism of alveoli. We further demonstrated that the thickness of the bubble film was closely correlated to mass transfer resistance theory, while the gas selectivity was completely unaffected. This innovative DLBM generation device is a highly attractive and promising prototype for designing a green and highly efficient gas/vapour separation membrane technology.

PH and Design on n-Alkyl Alcohol Bulk Liquid Membranes for Improving Phenol Derivative Transport and Separation.

Regardless of the type of liquid membrane (LM) (Bulk Liquid Membranes (BLM), Supported Liquid Membranes (SLM) or Emulsion Liquid Membranes (ELM)), transport and separation of chemical species are conditioned by the operational (OP) and constructive design parameters (DP) of the permeation module. In the present study, the pH of the aqueous source phase (SP) and receiving phase (RP) of the proposed membrane system were selected as operational parameters. The mode of contacting the phases was chosen as the convective transport generator. The experiments used BLM-type membranes with spheres in free rotation as film contact elements of the aqueous phases with the membrane. The target chemical species were selected in the range of phenol derivatives (PD), 4–nitrophenol (NP), 2,4–dichlorophenol (DCP) and 2,4–dinitrophenol (DNP), all being substances of technical-economic and environmental interest. Due to their acid character, they allow the evaluation of the influence of pH as a determining operational parameter of transport and separation through a membrane consisting of n–octanol or n–decanol (n–AlcM). The comparative study performed for the transport of 4–nitrophenol (NP) showed that the module based on spheres (Ms) was more performant than the one with phase dispersion under the form of droplets (Md). The sphere material influenced the transport of 4–nitrophenol (NP). The transport module with glass spheres (Gl) was superior to the one using copper spheres (Cu), but especially with the one with steel spheres (St). In all the studied cases, the sphere-based module (Ms) had superior transport results compared to the module with droplets (Md). The extraction efficiency (EE) and the transport of 2,4–dichlorophenol (DCP) and 2,4–dinitrophenol (DNP), studied in the module with glass spheres, showed that the two phenolic derivatives could be separated by adjusting the pH of the source phase. At the acidic pH of the source phase (pH = 2), the two derivatives were extracted with good results (EE > 90%), while for pH values ranging from 4 to 6, they could be separated, with DCP having doubled separation efficiency compared to DNP. At a pH of 8 in the source phase, the extraction efficiency halved for both phenolic compounds.

Experimental and Theoretical Study of an Autowave Process in a Magnetic Fluid.

Magnetic fluid (MF) is a colloidal system consisting of ferromagnetic particles (magnetite) with a diameter of ~10 nm suspended in a dispersion medium of a carrier fluid (for example, kerosene). A distinctive feature of magnetic fluid is the fact that when an electric field is applied to it using two electrodes, thin layers consisting of close-packed particles of the dispersed phase are formed in the regions near the surface of both electrodes. These layers significantly affect the macroscopic properties of the colloidal system. In this work, the interpretation of the near-electrode layer is for the first time given as a new type of liquid membrane, in which the particles of the dispersed phase become charged with the opposite sign. On the basis of experimental studies, we propose a physicochemical mechanism of the autowave process in a cell with a magnetic fluid. It is based on the idea of oppositely recharging colloidal particles of magnetite in a liquid membrane. A mathematical model of an autowave process, which is described by a system of coupled partial differential equations of Nernst–Planck–Poisson and Navier–Stokes with appropriate boundary conditions, is proposed for the first time. One-dimensional, two-dimensional, and three-dimensional versions of the model are considered. The dependence of the frequency of concentration fluctuations on the stationary voltage between the electrodes was obtained, and the time of formation of a liquid membrane was estimated. Qualitative agreement between theoretical and experimental results has been established.

Improving the Performance of Polymer Inclusion Membranes in Separation Process Using Alternative Base Polymers: A Review

Polymer inclusion membrane (PIM) has recently evolved as an alternative separation technique to conventional solvent extraction as it eliminates the use of toxic solvents, reduces separation cost, and simplifies the separation process. PIM is the new generation of a liquid membrane made by casting solution containing liquid phases (extractant and plasticizer/modifier) and base polymers. Despite its better performance and stability in comparison to the previous types of liquid membranes, PIM's robustness for applications on an industrial scale is still considered insufficient mainly due to its limited stability in the long-term separation process. In recent years, different approaches have been devoted to improving the stability of PIM while maintaining its performance. This review aims to summarize and evaluate the current literature on the improvement of the performance of PIMs with particular focus on the use of alternative base polymers, including non-conventional linear homopolymers, copolymers, or cross-linking polymers. Furthermore, more emphasis is given to the composition, fabrication process, and application of the PIMs. Finally, the performance of the PIMs with the alternative base polymers in terms of extraction rate and long-term stability is presented and compared to the PIMs fabricated using their corresponding common base polymers.

Studying of the effect of many parameters on a bulk liquid membrane and its opposition in Cd(II) removal from wastewater

Because of their tendency to accumulate in the body and their highly toxic potential, heavy metal pollution is becoming one of the main problems globally. The presented study examined the likelihood of eliminating heavy metals by means of the Bulk Liquid Membrane (BLM) method, which is a tool of high importance in various applications of such type. BLM is a simple type of liquid membrane which is showing excellent membrane stability yet insignificant solute fluxes. Therefore, this study outlines the BLM’s membrane resistance in removing heavy metals and recovery from the waste-waters. The cadmium (Cd) ions are fully prepared from the acidic aqueous solutions in this study with the use of the BLM. With regard to stirred transfer cell type, an experimental research has examined the recovery and extraction of Cd ions from synthetic wastewater solution via carrier Tri-butyl-phosphate TBP [C12H27O4P] with the use of BLM as an approach of separation. The impact of some parameters such as feed and stripping stirring speed, carrier concentration, membrane stirring speed, initial feed concentration, temperature, feed, and stripping phase pH is assessed for Cd removal. At pH 4 for feed, pH 10 for strip, 10 %(v/v) carrier concentration, 2 ppm initial concentration, 150 rpm,(S:F) = (1:1) in toluene, and the room temperature the maximal efficiency of extraction and stripping of cadmium (II) metal ions was 82 % and 93 %.

Microbubble Generation in Organic Solvents by Porous Membranes with Different Membrane Wettabilities

Microbubbles have gained universal interest due to their wide applications in water treatment, cosmetics, and pharmaceutical industry and potential applications in gas–liquid reactions such as hydrogenation and oxidation. However, microbubble formation in organic solvents has been seldom investigated. A controllable and efficient platform is built to investigate microbubble formation in organic solvents using a hydrophilic ceramic membrane and a hydrophobic polytetrafluoroethylene (PTFE) membrane. The effect of membrane wettability on the size of microbubbles is studied with the change of the liquid property and membrane type. Experimental results show that the sizes of microbubbles are in ranges of 130–453 μm and 59–387 μm using the hydrophilic ceramic membrane and the hydrophobic PTFE membrane, respectively. Microbubbles generated in organic solvents using the hydrophilic ceramic membrane are much larger than those in water, and the size of microbubbles formed using the hydrophobic PTFE membrane shows an opposite trend. Furthermore, an equivalent pore is introduced to develop mathematical model to predict the microbubble size, which agrees well with the experimental data.

The Influence of Plasticizers on the Response Characteristics of the Surfactant Sensor for Cationic Surfactant Determination in Disinfectants and Antiseptics.

Surfactant liquid-membrane type sensors are usually made of a PVC, ionophore and a plasticizer. Plasticizers soften the PVC. Due to their lipophilicity, they influence the ion exchange across the membrane, ionophore solubility, membrane resistance and, consequently, the analytical signal. We used the DMI-TPB as an ionophore, six different plasticizers [2-nitrophenyl-octyl-ether (P1), bis(2-ethylhexyl) phthalate (P2), bis(2-ethylhexyl) sebacate (P3), 2-nitrophenyl phenyl ether (P4), dibutyl phthalate (P5) and dibutyl sebacate (P6)] and a PVC to produce ionic surfactant sensors. Sensor formulation with P1 showed the best potentiometric response to four usually used cationic surfactant, with the lowest LOD, 7 × 10−7 M; and potentiometric titration curves with well-defined and sharp inflexion points. The sensor with P6 showed the lowest analytical performances. Surfactant sensor with P1 was selected for quantification of cationic surfactant in model solutions and commercial samples of disinfectants and antiseptics. It showed high accuracy and precision in all determinations, with recovery from 98.2 to 99.6, and good agreement with the results obtained with surfactant sensor used as a referent one, and a standard two-phase titration method. RDS values were lower than 0.5% for all determinations.

Salinity Gradient Energy Conversion Using Permselective Organic Liquid Membranes

The increases of worldwide energy consumption and the concern about the environment have made us pay attention to eco-friendly and renewable energy, such as solar power, wind power, water power, geothermal power, biofuel energy, etc. [P. A. Owusu and S. Asumadu-Sarkodie, Cogent Eng., 3, 1167990 (2016)]. The salinity gradient between seawater and river water must be one of such energy sources. Reverse electrodialysis (RED) is a power generation system which translates salinity gradient energy to electricity by the use of ion-exchange membranes [Y. Mei and C. Y. Tang, Desalination, 425, 156 (2018)]. Since the waters are sufficient on Earth and RED using them does not generate harmful waste, RED can supply electricity in a sustainable and eco-friendly manner. However, the drop in the power capacity owing to the large resistance of the river water, the high cost of ion-exchange membranes, deterioration and clogging of ion-exchange membranes, etc. are serious problems to be solved.We used organic liquid membranes instead of ion-exchange membranes as the permselective membranes for a RED system. Liquid membranes are often employed in the field of ion sensors in order to give electrodes the selectivity on the objective ions. The permselectivity of the liquid membranes is attributed to both the difference in the transfer energies of coexisting ions and the concentration ratio of them. The characteristics of the liquid-membrane type electric cell were studied.A Na+-permselective liquid membrane (Na+-LM) was prepared in the following manner. First, a 0.2-mm-thick polytetrafluoroethylene (PTFE) sheet opening a hole of 1.0 cm diameter was put on a flat glass plate and was fixed with clips. 74 mg of Sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaTFPB), 100 mg of polyvinyl chloride (PVC), and 0.8 mL (L = dm3) of 2-nitrophenyl octyl ether (NPOE) were dissolved in 4 mL of tetrahydrofuran (THF). Then, 0.1 mL of the THF solution was poured into the hole, and the solvent was dried for a day. Finally, a Na+-LM was formed within the hole on the glass plate. The membrane was peeled off from the glass plate and was used along with the PTFE sheet. Similarly, a Cl−-permselective liquid membrane (Cl−-LM) was prepared by the use of a THF solution containing 42 mg of tetraoctylammonium chloride (TOcACl), 100 mg of PVC, and 0.8 mL of NPOE in 4 mL of THF. The thickness of the membranes (Na+-LM and Cl−-LM) was 13 μm.The cell is mainly composed of three aqueous phases (W1, W2, and W3), two permselective liquid membranes (Na+-LM and Cl−-LM), and two Ag|AgCl electrodes (RE1 and RE2). The composition of the cell is as follows: RE1|W1|Na+-LM|W2|Cl−-LM|W3|RE2. W1 and W3 contained 1.0 mol L−1 NaCl aqueous solutions, which corresponded to seawater. A 50 mmol L−1 NaCl aqueous solution simulating river water was used as W2. The thickness of W1 and W3 and that of W2 are 2.3 cm and 2.8 cm, respectively.The power density of the cell was evaluated by normal pulse voltammetry. The potential of the cell, E, was taken as the potential of RE2 against RE1. In each step, E was maintained at the electromotive force E emf (or the open circuit potential) for 370 s, and then the rectangular pulse voltage was applied for 50 s. The current due to the Na+ flow from W1 to W3 was taken to be positive. The measurement was conducted at 298 ± 1 K.The result is shown in the attached figure. The time-course of the current density j and that of E were expressed as a solid line and a broken line, respectively. The measured value of E emf was 138 mV under the conditions. The calculated value of E emf by the Nernst equation using the activities of Na+ and Cl− is 140 mV, and the agreement between the two E emf values demonstrates that Na+-LM and Cl−-LM played as ideal permselective membranes. In order to evaluate the power density of the cell, the values of j at the last 2 s of each pulse were averaged and were related to the E values. The maximum power density was 14 μW cm−2 at 69 mV.In the present study, the liquid membranes were used instead of ion-exchange membranes for the RED system. The NPOE solution of NaTFPB and that of TOcACl showed the good permselectivity in the NaCl aqueous solution. The liquid membranes are able to replace the ion-exchange membranes used in RED systems. Figure 1

Pollution Control of Nitrate-selective Membrane by the Inner Solution and On-site Monitoring of Nitrate Concentration in Soil.

A liquid-membrane type nitrate-selective electrode was improved to lower the influence of contaminants by modifying its inner electrode system from Ag | AgCl | Cl- to Ag | Ag+. The NO3--selective electrode displayed a linear response to the concentration of NO3- with a Nernstian slope of -53 ± 1 mV decade-1, in the concentration region between 10-5 and 2 mol dm-3 (M). The NO3- detection limit was about 10-5 M. The electrochemical response of this electrode was stable for more than 30 days. The deterioration in responding characteristics due to the coexistence of Cl- was suppressed by use of the Ag | Ag+ redox couple in the absence of Cl- inside the NO3--selective electrode.

Construction of a Liquid Membrane Cell for Power Generation Based on Salinity Gradient Energy Conversion

Using two types of liquid membranes having Na+- and Cl−-permselectivities, novel power generation devices were composed. Electric power was generated based on salinity gradient energy conversion. S...

Reference Electrodes with Polymer-Based Membranes-Comprehensive Performance Characteristics.

Several types of liquid membrane and solid-state reference electrodes based on different plastics were fabricated. In the membranes studied, equitransferent organic (QB) and inorganic salts (KCl) are dispersed in polyvinyl chloride (PVC), polyurethane (PU), urea-formaldehyde resin (UF), polyvinyl acetate (PVA), as well as remelted KCl in order to show the matrix impact on the reference membranes’ behavior. The comparison of potentiometic performance was made using specially designed standardized testing protocols. A problem in the reference electrode research and literature has been a lack of standardized testing, which leads to difficulties in comparing different types, qualities, and properties of reference electrodes. Herein, several protocols were developed to test the electrodes’ performance with respect to stability over time, pH sensitivity, ionic strength, and various ionic species. All of the prepared reference electrodes performed well in at least some respect and would be suitable for certain applications as described in the text. Most of the reference types, however, demonstrated some weakness that had not been previously highlighted in the literature, due in large part to the lack of exhaustive and/or consistent testing protocols.

Desalination using modified configuration of supported liquid membrane with enhancement of mass transfer of NaCl.

Supported liquid membranes (SLM) suffer from very slow mass transfer of the solute from the donor phase (DP) to the receptor phase (RP) through the liquid membrane (LM). In the present work, an attempt was made to accelerate the mass transfer in SLM by creating a modified configuration in which the DP and RP are made to flow either co- or counter-currently to each other. Variables, which could affect the removal of NaCl, were the volume ratio of DP to RP, type and quantity of sequestering agent (SA), presence of mobile carrier (MC), type of LM, and flow rate of DP and RP. The results showed that the higher the flow rate of DP and RP, the higher the mass transfer of NaCl. Quantity and type of SA and type of LM were prime important factors. Remarkably, the time required for transfer of NaCl from DP to RP was reduced from several hours in the case of stagnant SLM to several minutes in the present work. The mass transfer of NaCl was analysed based on kinetic laws of two consecutive irreversible first-order reactions. The values achieved establish the process is diffusion controlled, and the membrane entrance rate constants increase directly with initial concentration (Ci) and inversely with quantity of SA.

Construction of Nitrate-selective Electrodes and Monitoring of Nitrates in Hydroponic Solutions.

A liquid-membrane type nitrate-selective electrode was constructed, in which the responding membrane contained polyvinylchloride, o-nitrophenyloctylether and tetraheptylammonium nitrate. The NO3--selective electrode displayed a linear response to the concentration of NO3- with a Nernstian slope of -53.3 ± 1.0 mV decade-1, in the 10-5 - 10-1 mol dm-3 (M) NO3- concentration range. The NO3- detection limit was about 10-6 M. The electrochemical response of this electrode was stable for more than 30 days. Measurements performed using the NO3--sensor indicated that in the presence of green plants, the concentration of NO3- in a hydroponic solution decreased from 0.20 to 0.05 mM over a three-day period.

Research on a New Pretreatment Technology for High Temperature Exhaust of Motor Vehicle

In order to ensure that the vehicle exhaust analyzer can work normally with the harsh conditions of the high temperature exhaust, the sample gas must be dewatered, dedusted and cooled without distortion. A new pretreatment technology for motor vehicle exhaust has been proposed in this paper. On the basis of the principle of cyclone separator with particles filter chamber, cyclone separator, liquid resistance and membrane type dryer as main devices, the particles filter chamber for dedusting, metal spiral pipe for cooling, cyclone separator for dewatering and dedusting, liquid resistance and membrane type dryer for dewatering have been used in the designed system. It can pretreat the exhaust without changing the exhaust composition, so the sample gas clarity can be increased. Field experiment results show that the designed pretreatment system can remove more than 5 um particle diameter. With it the exhaust temperature of range (180,210)°C can drop to around 39°C, the relative exhaust humidity of range (65,75)% can fall to about 25%, which can ensure the long-term stable operation of the online analysis instrument for high temperature exhaust.

Determination of Non‐Steroidal Anti‐Inflammatory Drugs in Urine by HPLC–UV/Vis Analysis Coupled with Electromembrane Extraction

A simple, effective, and environment‐friendly sample preparation method featuring electromembrane extraction followed by high‐performance liquid chromatography analysis was developed for the simultaneous determination of non‐steroidal anti‐inflammatory drugs (indoprofen, ketoprofen, naproxen, and ibuprofen) in human urine. Optimization was performed for parameters such as sample dilution, liquid membrane type, donor/acceptor solution pH, stirring speed, voltage, and extraction time. For spiked samples, the limits of detection and quantitation equaled 0.20–0.27 and 0.68–0.84 μg/mL, respectively, with the accuracy and precision in the working range equaling 95.1–128.4 and 2.71–10.2%, respectively. Linear equations used for quantitative analysis were valid in the concentration range of 0.68–8.4 μg/mL, with correlation coefficients (R) equaling 0.9934–0.9979.

Optimization of cyanide extraction from wastewater using emulsion liquid membrane system by response surface methodology.

To solve the disposal problem of cyanide wastewater, removal of cyanide from wastewater using a water-in-oil emulsion type of emulsion liquid membrane (ELM) was studied in this work. Specifically, the effects of surfactant Span-80, carrier trioctylamine (TOA), stripping agent NaOH solution and the emulsion-to-external-phase-volume ratio on removal of cyanide were investigated. Removal of total cyanide was determined using the silver nitrate titration method. Regression analysis and optimization of the conditions were conducted using the Design-Expert software and response surface methodology (RSM). The actual cyanide removals and the removals predicted using RSM analysis were in close agreement, and the optimal conditions were determined to be as follows: the volume fraction of Span-80, 4% (v/v); the volume fraction of TOA, 4% (v/v); the concentration of NaOH, 1% (w/v); and the emulsion-to-external-phase volume ratio, 1:7. Under the optimum conditions, the removal of total cyanide was 95.07%, and the RSM predicted removal was 94.90%, with a small exception. The treatment of cyanide wastewater using an ELM is an effective technique for application in industry.