Liquid Membrane System Research Articles

Emulsion liquid membrane pertraction of soap from crude biodiesel using activated carbon and glycol based deep eutectic solvents

Soap removal from crude biodiesel is considered as one of the most challenging biorefinery processes. This study reports a new technique for soap removal incorporating activated carbon (AC) in an emulsion liquid membrane (ELM) system based on deep eutectic solvents (DES-AC-ELM). These DESs were prepared from two salts, namely tetramethylammonium chloride (TMAC) and choline chloride (ChCl), with different hydrogen bond donors (HBDs) such as ethylene glycol (EG), diethylene glycol (DEG) and triethylene glycol (TEG). COSMO-RS modelling was performed in the evaluation of the activity coefficients and capacity at infinite dilution of DESs. The COSMO-RS simulation shows that the DESs with TEG as the HBD are the most effective stripping agents for soap removal which is in accordance with the experimental results. In addition, the σ-profile and σ-potential were used to investigate the interactions between the soap molecules in each phase. The impact of various process parameters on the soap removal such as the salt: HBD ratio, DES:biodiesel ratio, span-20 concentration, mixing speed, extraction time and dosage of AC were evaluated. The proposed technique achieved a soap extraction efficiency of 99.1% (6.856 ppm) and 97.5% (18.773 ppm) for TMAC:TEG(DES3) and ChCl:TEG(DES6), respectively, with a salt: HBD molar ratio of 1:4, DES:biodiesel ratio of 1:1, 2 wt% surfactant concentration, 10 min extraction duration, 400 rpm mixing speed, 0.5 treatment ratio and 0.5 wt% AC dosage. The transport mechanism of soap conforms to a first-order mass transfer behaviour, with a kinetic rate constant of 0.64 min−1 and 0.43 min−1, for DES3 and DES6, respectively. This study illustrated a new cleaner and simple route for purification of crude biodiesel.

Supported liquid membrane with selective stripping for separative recovery of copper and zinc from plating wastewater

For separation and recovery of different but chemically similar metal from dilute wastewater with reduced process complexity and cost, a supported liquid membrane (SLM) system that utilizes a single carrier together with strip dispersion for selective stripping of coextracted metal ions was proposed to enable concurrent separation and recovery. This study aims to investigate the effectiveness of the proposed SLM system for separative recovery of copper and zinc from real plating wastewater. Solvent extraction experiments were conducted to understand the effect of feed pH and carrier concentration on organic phase migration to the aqueous phase. The effect of stirring speed on the SLM transport rate was studied using synthetic feed. Combined with the insights from our previous study, appropriate settings were identified and applied to the SLM system. The SLM system could recover 83.7% copper with 91.0% purity and 85.5% Zn with 99.3% purity from the plating wastewater in 30 h. The findings indicate the feasibility of using SLM with selective stripping for the concurrent separation and recovery of copper and zinc from a dilute aqueous waste stream predominantly containing these two metals.

Natural eutectic solvents and graphene integrated within emulsion liquid membrane system for sodium removal from crude biodiesel

This study reports a new technique for sodium ion removal from biodiesel using a green emulsion liquid membrane (GELM) system based on natural deep eutectic solvents (NADESs) and graphene. The DES consists of choline chloride with glycerol and lactic acid, and tetramethylammonium chloride with glycerol and lactic acid. COSMO-RS software was used to compute the intermolecular interaction of sodium with hydrogen bond acceptors and donors of the NADES. The simulation shows that NADES was the most effective stripping phase for sodium ion removal, which follows the experimental results. The investigation on the stability of ELM and sodium (830 ppm of initially) extraction efficiency showed that the GELM-NADES technique can achieves a sodium ion extraction efficiency of 99.6 % (3.17 ppm) with high stability at a homogenization speed of 8000 rpm, homogenization time of 3 min, HBA: HBD molar ratio of 1:4, 3 wt% of span 80, 10 minutes of extraction time, 400 rpm stirring speed and 0.5 treatment ratio. The presence of graphene (0.3 g) in the system further enhanced the efficiency and shortened the required extraction time from 6 to 4 min to meet the ASTM D6752 standards. The transport mechanism of sodium ions into the ELM phases adheres to the first-order kinetics model and film theory mechanisms. The overall mass transfer coefficient KO, mass transfer coefficient of the external phase in agitated reactor KM, and interfacial reaction rate constant KF of 5.188×10−9,1.373×10−7,and 5.392×10−9 m/s, respectively. ELM system with NADES and graphene can provide a cleaner route for biodiesel downstream processing.

Solvent Extraction of Gold(III) by 2-Ethylhexanol and Modeling of Facilitated Transport across a Supported Liquid Membrane

The solvent extraction of gold(III) by undiluted 2-ethylhexanol or dissolved in toluene from a HCl solution has been investigated in this paper. The numerical analysis of gold distribution data suggests the formation of HAuCl4·L and HAuCl4·2L (L = 2-ethylhexanol) species in the organic phase, with formation constants K11 = 38 and K12 = 309, respectively. The results derived from gold(III) distribution have been implemented in a solid-supported liquid membrane system. The influence of several variables on gold transport has been considered: feed and receiving phases’ stirring speeds, HCl and gold concentrations in the feed phase, and carrier concentration in the membrane phase as well as the presence of base metals (Fe, Cu, Ni) and platinum-group metals (PGMs) in the feed phase. Gold transport is influenced by the stirring speed of the feed phase and the variation in HCl and gold (feed phase) and carrier (membrane phase) concentrations. Also, diffusional resistances to mass transfer are estimated, and the contribution of each resistance to gold transport is estimated. Gold is recovered as zero-valent nanoparticles.

Hollow fiber liquid membrane: A promising approach for elimination of pharmaceutical compounds from wastewater

Pharmaceutical compounds present in water pose significant challenges, particularly due to their low concentrations in water streams. Hollow fiber liquid membranes provide a flexible and easily manageable solution, enabling the concentration of specific contaminants. This concentration step significantly improves their effective removal from water systems. The study focused on using hollow fiber liquid membrane technology to effectively remove diclofenac (DCF) and ibuprofen (IBU), two pharmaceutical compounds. A concentration of 40% Cyanex 923 (Cy923) dissolved in kerosene was selected as the preferred extractant due to its stability and quick extraction properties. The stability of the system was tested with a pseudo-emulsion, enabling repeated use of the system. Additionally, an analytical model was developed to calculate the membrane's permeability. In order to enhance the degradation and mineralization of the pharmaceutical compounds and their byproducts, ozonation was integrated with the hollow fiber liquid membrane system in a single system. Measurement of total organic carbon (TOC) revealed a significant reduction of 72% for diclofenac and 57% for ibuprofen with an initial ozone concentration of 10 mg/L and operating under the optimal conditions of hollow fiber liquid membrane.

A systematic study on the determination of optimal transport conditions for methylene blue using new generation Pillar[5]arene-based bulk liquid membrane in aqueous phase

Most of the dyes are toxic chemicals with mutagenic and carcinogenic effects on humans and need to be purified from water and other sources. Therefore, new substances with high selectivity towards these substances’ discovery is very important. In this paper, a pillar[5]arene derivative including ten iodine moieties, the newest member of macrocycles, was synthesized and used for the removal of methylene blue (MB) using a bulk liquid membrane system and named P[5]-iodine. The synthesized Pillar[5]arene derivative was characterized by using of various techniques, NMR, FT-IR, elemental analysis, melting point etc. The optimum conditions for the transport process were experimentally determined that the pH of the donor phase and acceptor phase as 6 and 3, respectively. The experimental results showed that the pillar[5]arene carried efficiently to MB at 298 K by using dichloromethane as a solvent in 10-3 M and 10-4 M concentrations for the membrane and the donor phase, respectively. The best transporting of MB as a cationic dye toward water (complexing between membrane/donor) was carried out under the optimum conditions that pH is the most important of the parameters examined as a driving force. The kinetic parameters and activation energies were calculated at various temperatures. The activation energies (Ea1: 2.69 kcal/mol, Ea2: 7.66 kcal/mol) indicate effective and feasible transport mechanisms. As result, the prepared Bulk Liquid Membrane/P[5]-iodine hybrid system has a highly sensitivity in the transport of MB.

Integration of deep eutectic solvent and activated carbon in emulsion liquid membrane system for soap removal from crude biodiesel

The present work investigated the soap removal from crude biodiesel (BD) using a new technique known as (DES-based ELM/AC), which is a deep eutectic solvent (DES) -based emulsion liquid membrane with the presence of activated carbon (AC). In this system, the DES was introduced as a stripping phase in the DES-ELMs while the AC was introduced into the membrane phase as due to its interaction with the potassium species in the soap molecules with the presence of active sites on the AC surface. The effect of different parameters on the soap extraction efficiency such as the DES molar ratio, DES: BD ratio, surfactant concentration, mixing speed, duration process, and AC dosage were investigated. The results showed that in comparison to adsorption and DES-based ELM, the synergistic effect provided by DES-based ELM/AC technique showed superior removal efficiency at 97.61%. Highest removal efficiency of 99.75%, which is equivalent to 1.87 ppm soap content in the BD, was achieved at 2 wt% of the surfactant, 0.5 wt% of AC, 1:4 DES molar ratio as stripping phase, 1:1 DES: BD ratio, 400 rpm mixing speed and 6 min extraction time. The soap transport follows the first order kinetic model, with a rate constant of 0.627 min -1. This method offers a viable alternative to the conventional water-based purification process. It demonstrates the effective purification of crude BD without the use of a large amount of water/washing agent in comparison to conventional water washing, thereby offering a more sustainable solution for the purification of BD.

Investigation of a multi-dropped liquid membrane system for the transport of uranium ions with tri-n-octyl phosphine oxide

Investigation of a multi-dropped liquid membrane system for the transport of uranium ions with tri-n-octyl phosphine oxide

Design and manufacture of emulsion liquid membrane based on various amine extractants for separation and extraction of succinic acid from fermentation broth

The aim of this study was to design a new emulsion liquid membrane (ELM) system for the separation of succinic acid from aqueous solutions. The concentration of succinic acid varied from 20 to 60 mmol·L−1. The prepared ELM system includes tributylamine (TBA) as a carrier, commercial kerosene as a solvent, Span 80 as a surfactant, and Na2CO3 as a stripping agent. In order to control the membrane swelling, different values of cyclohexanone were added to the membrane phase. The effect of various empirical variables on the extraction of the succinic acid such as acid concentration in the feed solution, initial feed concentration, carrier concentration, the stirring speed of the extraction, Na2CO3, surfactant, and cyclohexanone concentrations, and treat ratio in the ELM system. The best result was obtained when TBA was used as the carrier. The final acid extraction efficiency was independent of pH variations of the aqueous feed solution. The extraction of succinic acid solution with a concentration of 40 mmol·L−1 was improved by increasing the treat ratio 1:7–1:3, stripping phase concentration 0.5–1.5 mol·L−1, stirring speed 300–500 r·min−1 and cyclohexanone concentration in the membrane phase 1.2–1.6 mol·L−1. No considerable effect on the extraction rate was observed for the carrier concentration in the membrane phase. But, the surfactant concentration in the feed phase showed a dual effect on the extraction efficiency.

Effect of Flow Operation Modes on Removal of Acetic Acid from Oil Palm Frond Biomass Hydrolysate using Hollow Fiber Supported Liquid Membrane

Acetic acid (AA) is considered an inhibitor in the oil palm frond (OPF) biomass hydrolysate solution. It can reduce the microorganism activity during sugar fermentation using OPF solution. In the current study, a hollow fiber supported liquid membrane (HFSLM) system using hybrid polyethersulfone-graphene membrane support and organic liquid membrane phase of 0.5 M tri-n-octyl amine carrier in a 2-ethyl-1-hexanol diluent was used to remove the AA. The liquid membrane impregnation time and the flow operation modes of the feed and strip phases in the HFSLM configuration were investigated. Mode I was operated with the feed phase flow inside the hollow fiber (HF) lumen and the stripping phase flow at the shell side. In mode II, the feed phase entered at the shell side and the stripping phase at the lumen of the HF support. The best liquid membrane impregnation time was 4 hours, exhibiting the highest AA removal efficiency of 80% compared to 1 and 24 hours of impregnation time. The removal efficiency of the AA was 80.1% and 42.4% using mode I and mode II, respectively, at 8 hours of the supported liquid membrane (SLM) running time. HFSLM was applied to remove AA from real OPF biomass hydrolysate. It was found that the AA concentration had reduced from 6.83 to 2.01 g/L after the SLM process. The SLM process did not affect the concentration of other components, especially sugar compounds in the OPF biomass hydrolysate.

Continuous Transport of Zn(II) by Ammonium Chloride Media via Supported Liquid Membrane System

AbstractWith the gradual depletion of traditional zinc resources, the full use of various non‐traditional zinc‐containing resources has received intensive attention. However, the efficient recovery of zinc ions with low concentrations remains challenging. Here efficient and continuous recovery of zinc ions in ammoniacal chloride media by a flat supported liquid membrane system is achieved, using Cyanex923 and TBP mixed extractant as the membrane phase. This article discusses the synergistic effect between Aliquat336, Cyanex923 and TBP, the effects of feed pH, total ammonia concentration, Cl− concentration and temperature on Zn(II) transport.

Chromium (III) Ions Were Extracted from Wastewater Effluent Using a Synergistic Green Membrane with a BinaryCombination of D2EHPA and Kerosene

This study used a supported liquid membrane system (SLM) using Celgard 2400 polypropylene as the support, di(2-ethylhexyl) phosphoric acid (D2EHPA) as the carrier, and kerosene as the diluent. To obtain the best carrier concentration, D2EHPA concentrations between 0.04 and 0.6 M were used. The Cr (III) solutions used in the feed phase had various ionic strengths and were adjusted with NaCl at concentrations ranging from 0.25 to 1.75 M. To maintain a constant pH (4) in the feed phase, a 0.2 M acetic acid–sodium acetate buffer was utilized. Because the rate of Cr (III)-carrier complex formation at the interface of the feed solution and membrane increased up to 20 × 10−4 mol/L, it was discovered that transport of Cr (III) rose with an increase in chromium content in the feeding phase. For the optimization of the various stripping agents, HCl concentration was employed, from 0.25 M to 1.75 M. It was observed that Cr (III) transport increased with the increase in HCl concentration because the transport was at a pH gradient, which was the main driving force. Because of the fact that at the feed phase-membrane contact, D2EHPA combined with chromium ions to form the Cr (III)-carrier complex and released H+ protons, in the feed phase, the Cr (III)-carrier complex was diffused into a stripping phase, wherein Cr (III) ions were stripped and the carrier was reversibly protonated again.

Application of natural deep eutectic solvents in bulk liquid membrane system for removal of free glycerol from crude fatty acid methyl ester

Fatty Acid Methyl Ester (FAME) produced from biomass offers several advantages such as renewability and sustainability. The typical production process of FAME is accompanied by various impurities such as alcohol, soap, glycerol, and the spent catalyst. Therefore, the most challenging part of the FAME production is the purification process. In this work, a novel application of bulk liquid membrane (BLM) developed from conventional solvent extraction methods was investigated for the removal of glycerol from FAME. The extraction and stripping processes are combined into a single system, allowing for simultaneous solvent recovery whereby low-cost quaternary ammonium salt-glycerol-based deep eutectic solvent (DES) is used as the membrane phase. Moreover, for the first time, diethyl ether was introduced as a strip phase to strip the free glycerol in the BLM system. The effects of DES composition, DES:FAME ratio, stirring speed and operating time on the extraction and stripping efficiencies were investigated. A kinetic model was proposed for the transportation of free glycerol through the DES-based BLM, where the kinetic parameters (k1, k2, tmax, GMmax) for the extraction and stripping were calculated using the glycerol content in the feed and the strip phase. The performance of the lab-scale BLM system confirms the viability of the proposed system with a best DES molar composition of 1:2 (salt:glycerol), DES:FAME ratio of 1:1, mixing speed of 200 rpm and an extraction time of 4 hr. Glycerol content in the purified FAME meets the international standards such as EN 14214 and ASTM D6759. Under the optimal conditions, the suggested model curves of glycerol content in the feed, membrane, and strip phases showed a good fitting with the experimental results. Finally, the rate constants values of the kinetic model were 0.0037 min−1 for k1 and 0.0066 min−1 for k2.

Application of solubility data on a hollow fiber supported liquid membrane system for the extraction of gold (I) cyanide from electronic industrial wastewater

The solubility ternary system was used to develop a hollow fiber-supported liquid membrane process for the extraction of gold (I) cyanide from electronics industry wastewater. Five kinds of diluents (p-xylene, cyclohexene, 1-dodecanol, n-heptane, and n-dodecane) were applied to the solubility of ternary systems (Aliquat336 + water + diluents) at 303.2 K and atmospheric pressure. 1-dodecanol, p-xylene, and cyclohexane were selected because they are completely soluble in Aliquat336 in any composition. The effects of pH on the feed solution and type of diluent were examined. The highest extraction and stripping percentages of 99.9 and 61.4, respectively, were achieved at a feed solution pH of 10.0 using p-xylene as the best diluent.

Single and selective transport of Zr(IV) ions with trioctyl amine dissolved in kerosene using a multidropped liquid membrane technique.

It is very important to develop a process for selectively extracting Zr(IV) ions from the solution medium to produce zirconium metal used in industry and nuclear reactors. In this study, the parameters affecting the extraction of Zr(IV) ions were investigated using a multidropped liquid membrane (MDLM) system. Trioctyl amine (TOA) dissolved in kerosene was used as a carrier ligand in the extraction of Zr(IV) ions by the MDLM technique. The effect of carrier concentration and stripping solution concentration, pH, and the temperature in the donor phase on the transport of Zr(IV) were investigated. The optimum condition for the transportation of Zr(IV) was a 0.50 M H2SO4 solution as donor phase, 0.10 molL-1 TOA as a carrier, and 0.10 M Na2CO3 as acceptor phase. The transport percentage of Zr(IV) was increased up to >99% and the calculated activation energy which is 6.36 kcal mol-1 indicated that the process was diffusion controlled by Zr(IV) ions. The results showed that the MDLM system, which resembles a bulky membrane system in shape, is a promising technique for the extraction of Zr(IV) ions from an acidic solution. It is more practical and effective than bulk, supported, or inclusion, and emulsion liquid membrane techniques.

Mathematical Modeling of Extraction of Neodymium using Pseudo-emulsion based Hollow Fiber Strip Dispersion (PEHFSD)

Pseudo-emulsion based hollow fiber strip dispersion (PEHFSD) is a promising alternative technique due to its stability, simplicity and cost of operation. This is an efficient process due to its high surface area for extraction as well as stripping, and low energy consumption for creating the pseudo-emulsion and for the separation of phases. This technique takes the combine advantages of emulsion liquid membrane and overcomes the sufferings of membrane stability in the supported liquid membrane systems. Present work includes extraction of neodymium (III) (Nd) by using TODGA and HNO3 as the extractant cum strippant in PEHFSD technique. A model is developed to study the transport of Nd under different hydrodynamic and chemical conditions that includes organic ratio (A/O) in dispersion, effect of speed of impeller on drop size formation, effect of feed acidity, effect of carrier concentration, effect of feed flow rate. A code is written to solve the model equations numerically to predict the concentration of the feed reservoir with time. Experiments are conducted to obtain the best optimum extraction conditions. Results obtained from the numerical simulations are validated with the experimental data and found a good agreement between them.

New challenges and applications of supported liquid membrane systems based on facilitated transport in liquid phase separations of metallic species

The linear economic model based on “take-make-dispose” has become unsustainable, revealing the necessity of shifting towards a circular economy approach, in which secondary raw materials play a key role in closing material cycles. In this context, industrial effluents with metallic content, are considered a potential secondary source for these elements, the lack of the availability of the appropriate technology being the main barrier when implementing circular economy principles at industrial scale. In this regard, supported liquid membrane systems based on facilitated transport may be decisive. Thus, the objective of this research paper is to show the potential of facilitated transport systems to foster the transition to a more sustainable management of industrial metallic effluents. To accomplish that, three different applications of supported liquid membrane systems in acidic industrial effluents will be presented: a) Zn/Fe separation, b) Ni/Cd separations and c) Removal of hexavalent Cr. Additionally, the recovery and separation of two different critical raw materials, i.e. Li and rare earth elements will be discussed. Although facilitated transport systems have been successfully applied to both, Zn/Fe and Ni/Cd separation, as well as to hexavalent Cr removal, further work should be done for the successful recovery and separation of Li and rare earths with supported liquid membrane systems, especially in terms of selectivity improvement and validation with real industrial effluents.

Silver extraction using emulsion liquid membrane system containing D2EHPA-TBP as synergistic carrier: optimization through response surface methodology

ABSTRACT The present investigation deals with silver extraction using an emulsion liquid membrane. The emulsion liquid membrane system consists of paraffin as organic phase, Span 80 as surfactant, Di-(2-ethylhexyl) phosphoric acid (D2EHPA) and Tributyl Phosphate (TBP) as carrier, and hydrochloric acid as stripping agent. Experiments were designed and modeled by response surface methodology using Design Expert 11 software, which determines the extraction rate as a function of Span 80 concentration, D2EHPA concentration, TBP concentration, HCl concentration, and treatment ratio. The ANOVA results indicate that the model is statistically significant because of the high R 2 (0.9828) and the low p-value of <0.0001. The results showed that the silver extraction increases by increasing all affecting parameters up to their optimal values and after that extraction rate decreases with increasing of them. The process was optimized to obtain maximum extraction rate, minimum D2EHPA concentration, and minimum treatment ratio. The optimal conditions were obtained at a surfactant concentration 3.26% (V/V), D2EHPA concentration 0.0045 mol/L, TBP concentration 5% (V/V), HCl concentration 0.56 mol/L, and treatment ratio 0.5. Under these conditions, the silver extraction rate was 99.87%.

Separation and purification of polyprenols from Ginkgo biloba L. leaves by bulk ionic liquid membrane and optimizing parameters

Polyprenols extracted from Ginkgo biloba L. leaves (GBL) are known for their biological functions (antioxidant, antimicrobial, antivirus, hepatoprotective, and antitumor properties). Nevertheless, the conventional methods of polyprenol separation lack selectivity and has a low separation efficiency. As a result, effective methods for separating and purifying polyprenols have become a major research focus in the pharmaceutical and healthy food industries. In this study, the separation and purification of GBL’s polyprenols were performed. The transport of polyprenols from GBL via a bulk liquid membrane containing AgBF4 as a carrier was examined. The optimization parameters were: 1-hexene, 308 K, 500 rpm, 1% wt %, 72 h for the stripping phase, system temperature, stirring speed, the carrier concentration in membrane phase, and transport time, respectively. Additionally, the purity of polyprenols increased from 48.2% to 78.1%, recovery was 73.5 %, and a permeability coefficient of 0.24 cm/h was obtained under these conditions. The kinetic parameters (k1, k2, tmax, Rlmax, Jfmax, Jsmax) at 308 K were determined for the interface reactions assuming two consecutive irreversible first-order reactions as: 2.36 × 10−2, 0.87 × 10−2 (h−1), 68.64 (h), 0.57, −0.47 × 10−2 (h−1) and 0.47 × 10−2 (h−1), respectively. These values indicated that the polyprenols' transport process combines two processes: complex diffusion in the membrane phase and chemical reactions at two independent and possibly different interfaces. The experiments demonstrated that the bulk liquid membrane system significantly affected the separation and enrichment of polyprenols. The study provided an effective polyprenol separation and purification approach, and the basis for potential polyprenol-based medications, cosmetics, and health products.

Separation of Indole-3-acetic Acid from Tryptophan by Bulk Liquid Membrane

Background: Indole-3-acetic acid (IAA) is an important growth hormone for plants obtained by biosynthesis from tryptophan. Aim: In this paper was studied the competitive transport of two biologically active compounds, indole-3-acetic acid (IAA) and tryptophan (TRP) through a liquid membrane. Methods: The separation of the two compounds was obtained using a hybrid liquid membrane system having as a carrier trioctylphosphine oxide (TOPO). Results: The most important operational parameter of the system were studied, pH influence on the efficiency of the transport process in correlation with the speciation diagrams of the two compounds: TRP and IAA. The evaluation of the transport process was performed through calculating the composition of the phases at the end of the transport process and the organic substrate flow at the membranes exit. Conclusion: Due to the transport efficiency of over 90% in the case of IAA and the high selectivity at the transport between IAA and TRP, the procedure can be applied at the sample preparation containing these analytes.