Liquid Membrane System Research Articles

Application of bilinear least squares/residual bilinearization in bulk liquid membrane system for simultaneous multicomponent quantification of two synthetic dyes

For the first time, this research reports a new application of bulk liquid membrane (BLM) with second-order calibration based on the bilinear least squares/residual bilinearization (BLLS/RBL) algorithm, as a novel method for simultaneous removal and quantification of allura red (AR) and sunset yellow (SY) as model compounds in soft drinks and food samples. Due to severe spectral overlapping between the AR and SY and strong colinearities present in the data set, common second-order multivariate calibration methods, such as parallel factor analysis (PARAFAC) and multivariate curve resolution-alternating least-squares (MCR-ALS), could not be successfully applied to the presently studied samples. At first, the basic experimental parameters affecting the transport of the target dyes were investigated and optimized. Then under the optimum conditions, we have explored an alternative use of BLLS/RBL methodology, which can work adequately with strongly overlapping spectra and colinearities problems. Satisfactory results were obtained for analysis of target analytes. The proposed method was validated by comparison with a reference method based on high-performance liquid chromatography-ultra violet detection (HPLC-UV) and no significant differences were found between the reference values and the ones obtained with the proposed method. Such a chemometrics-based protocol may be a very promising tool for more analytical applications in real samples monitoring, due to its advantages of easy sample pretreatment, accuracy, sufficient spectral resolution and concentration prediction even in the presence of unknown interferences.

Arsenic removal by liquid membranes.

Water contamination with harmful arsenic compounds represents one of the most serious calamities of the last two centuries. Natural occurrence of the toxic metal has been revealed recently for 21 countries worldwide; the risk of arsenic intoxication is particularly high in Bangladesh and India but recently also Europe is facing similar problem. Liquid membranes (LMs) look like a promising alternative to the existing removal processes, showing numerous advantages in terms of energy consumption, efficiency, selectivity, and operational costs. The development of different LM configurations has been a matter of investigation by several researching groups, especially for the removal of As(III) and As(V) from aqueous solutions. Most of these LM systems are based on the use of phosphine oxides as carriers, when the metal removal is from sulfuric acid media. Particularly promising for water treatment is the hollow fiber supported liquid membrane (HFSLM) configuration, which offers high selectivity, easy transport of the targeted metal ions, large surface area, and non-stop flow process. The choice of organic extractant(s) plays an essential role in the efficiency of the arsenic removal. Emulsion liquid membrane (ELM) systems have not been extensively investigated so far, although encouraging results have started to appear in the literature. For such LM configuration, the most relevant step toward efficiency is the choice of the surfactant type and its concentration.

Transportation and kinetic analysis of Mo(VI) ions through a MDLM system containing TNOA as carrier

In this report, Mo(VI) ions are transported from an aqueous donor phase into an aqueous acceptor phase by a newly designed method called as multi dropped liquid membrane (MDLM) system prepared by dissolving TNOA as carrier in kerosene. During the extraction of Mo(VI) ions by the liquid membrane system; 100ppm Mo(VI) solutions as donor phase, buffer solution(pH:9.5) and Na2CO3 in different concentrations as acceptor phase and TNOA diluted by kerosen as organic phase are used.In our experimental work, the effect of temperature by using buffer solution and Na2CO3 in the acceptor phase and effect of concentration of acceptor phase on the extraction of Mo(VI) ions were investigated.Appropriate conditions for Mo(VI) transportation were as follows: pH of donor phase is 2.00, concentration of TNOA is 0.005M, 1.00M Na2CO3 as acceptor phase, and flux rate is 50mL/min. Besides, Mo(VI) ion transportation is consecutive first order irreversible reaction and the transportation of Mo(VI) ions is diffusion controlled process. The kinetic parameters (k1, k2, Rmmax, tmax, Jdmax, Jamax) were calculated for the interface reactions assuming two consecutive, irreversible first-order reactions.

Intensification of Europium extraction through a supported liquid membrane using mixture of D2EHPA and Cyanex272 as carrier

Solvent extraction and supported liquid membrane transport properties of Eu from nitric acid medium using mixture of D2EHPA and Cyanex272 as carrier were investigated. In the solvent extraction studies, maximum synergistic enhancement factor (R) of 2.3 was obtained for the D2EHPA/Cyanex272 mole fraction ratio of 0.5:0.5. The synergistic effect of these carriers intensified Eu pertraction in the supported liquid membrane system. The effects of feed phase pH, stirring rate, carrier concentration, stripping agent concentration and membrane pore size were investigated in the supported liquid membrane experiments. Some experiments were carried out by various membrane thicknesses and the linear relationship between permeability coefficient and (membrane thickness)−1 showed that the Eu transport is membrane diffusion limited. The stability of the membrane is satisfactory over 9 days.

Optimization of synergistic extraction of neodymium ions from monazite leach solution treatment via HFSLM using response surface methodology

The extraction of neodymium ions from monazite leach solution was achieved by synergistic extraction via hollow fiber supported liquid membrane (HFSLM). Applying the results from central composite design (CCD) experiments, further optimization experiments were carried out using response surface methodology (RSM). Validation tests revealed optimum performance at 0.1M Cyanex 272 and 0.05M TOPO, 4M HNO3 as the stripping solution and flow rates of both feed and stripping solutions were 100mL/min. The extraction of neodymium ions reached a maximum of 98%. Results indicated that the highest fractional resistance was a chemical reaction. This showed that mass transfer resistance due to chemical reaction was dominant for transport of neodymium ions through the hollow fiber supported liquid membrane system.

Dysprosium pertraction through facilitated supported liquid membrane using D2EHPA as carrier

AbstractThe pertraction of dysprosium (Dy) through a supported liquid membrane (SLM) system consisting of PTFE (polytetrafluoroethylene) support, D2EHPA (di-2-ethylhexyl phosphoric acid) dissolved in kerosene as membrane solution, and HNO3 solution as stripping solution, was studied. The experiments were designed by the Taguchi method in order to investigate the effects of initial Dy concentration, feed phase pH, different stripping solution concentration, and D2EHPA concentration in the membrane phase on Dy pertraction. Optimal experimental conditions for Dy pertraction were obtained using an analysis of variance (ANOVA) (feed concentration: 130 mg L

Nickel ion coupled counter complexation and decomplexation through a modified supported liquid membrane system

Complexation and decomplexation stoichiometry between nickel and D2EHPA in an SLM system are determined, confirmed by Job’s method and loading test.

Study of mean diameter and drop size distribution of emulsion drops in a modified rotating disc contactor for an emulsion liquid membrane system

Mean diameter and drop size distribution of emulsion drops in a modified rotating disc contactor for an emulsion liquid membrane system.

Separation of manganese from aqueous solution using an emulsion liquid membrane

The present study deals with the carrier-facilitated transport of manganese from an acidic leach solution in an emulsion liquid membrane system.

New bulk liquid membrane oscillator composed of two coupled oscillators with diffusion-mediated physical coupling

AbstractA new type of bulk liquid membrane system, which represents the first example of a bulk liquid membrane oscillator characterised by the presence of two coupled oscillators, is described. When the benzyldimethyltetradecylammonium chloride surfactant undergoes an oscillatory mass transfer through a nitromethane liquid membrane, a new liquid layer (phase X) appears between the membrane and the acceptor phase. Kinetic analysis provides evidence that the whole system is composed of two coupled oscillators with diffusion-mediated physical coupling. The first component oscillator (based on nitromethane) of lower frequency delivers the driving material to the second one (phase X-based oscillator) leading to additional higher frequency oscillations. A new molecular mechanism is proposed for interpreting the experimental observations. The results might enhance understanding of intercellular communication in biology, where periodic signalling is more efficient than any other type of signalling mode.

Separation of mercury(II) from petroleum produced water via hollow fiber supported liquid membrane and mass transfer modeling

The separation of mercury(II) from petroleum-produced water from the Gulf of Thailand was carried out using a hollow fiber supported liquid membrane system (HFSLM). Optimum parameters for feed pretreatment were 0.2M HCl, 4% (v/v) Aliquat 336 for extractant and 0.1M thiourea for stripping solution. The best percentage obtained for extraction was 99.73% and for recovery 90.11%, respectively. The overall separation efficiency noted was 94.92% taking account of both extraction and recovery prospects. The model for this separation developed along a combined flux principle i.e. convection–diffusion–kinetic. The results showed excellent agreement with theoretical data at an average standard deviation of 1.5% and 1.8%, respectively.

Enhancing performance of hybrid liquid membrane process supported by porous anionic exchange membranes for removal of cadmium from wastewater

In this study, polyethersulfone (PES)-based porous anionic exchange membranes (AEMs) are fabricated. The morphological and transport properties of the membranes such as pore size, roughness, porosity, water uptake, membrane transport number, fixed charge density, and conductivity are determined. These AEMs are used as supporting membranes to enhance the mass transfer flux in a hybrid liquid membrane (HLM) process for removal of cadmium from an acidic feed solution. The liquid membrane phase is prepared by dissolving triisooctylamine (TIOA) in kerosene. The effects of applying porous AEMs with different fixed charge densities, temperature, and initial cadmium concentration are investigated. It is confirmed that the main resistance in the mass transfer in the system is confined in the supporting membranes. Applying PES-based AEMs with a proper fixed charge density of X′=0.0197meq/cm3 instead of non-ionic PES supporting membranes can increase the mass transfer coefficient from 0.0068 to 0.017min−1. Almost all cadmium can be transferred within 3h. The proposed anionic supporting membranes can yield a much higher fluxes for removal of cadmium in high concentrations comparing to the same hybrid liquid membrane system with non-ionic PVDF supporting membranes while only insignificant loss in removal efficiency is observed.

Study of solar regenerated membrane desiccant system to control humidity and decrease energy consumption in office spaces

This paper investigates the feasibility of using a solar regenerated liquid desiccant membrane system to remove humidity from an office space. While conventional vapor compression cycles dehumidify the air before supplying it to the indoor space, through using sub cool–reheat process, the proposed cycle absorbs the humidity directly from indoor space through the dehumidifier. The dehumidifier consists of a set of permeable vertical tubes placed in the indoor space with liquid desiccant flowing through them. Solar energy is used as the source of thermal energy required for the regeneration of the desiccant and sea water is used as heat sink to provide the cooling needs of the liquid desiccant.A mathematical model of the membrane desiccant system was integrated with the internal space model and solar system model to predict the humidity removal capacity from the space at given dehumidification and heat sink temperatures and outdoor environmental conditions. Experiments were performed to validate the model results be comparing exit humidity and temperature of the exit air from the space.The validated model was applied to a case study consisting of an internal office during the month of August in Beirut hot humid climate. A decrease of 10% in indoor relative humidity is observed when the system was used. The cost of the proposed system was compared to the cost of a conventional vapor compression cycle that provides the same indoor conditions. A payback period of 7years and 8month was estimated compared to the investment in the vapor compression cycle.

N-benzoyl-n-phenylhydroxylamine (n-BPHA) carrier – mediated selective transport of thorium using bulk liquid membrane

The carrier activity of n-benzoyl-n-phenylhydroxylamine (n-BPHA) was examined for the possibility of selective transport of thorium across a bulk liquid membrane system, in the present work. The bulk liquid membrane setup based on the Schulman Bridge contained 25 ml of 10 4 M carrier solution in chloroform, as the membrane phase (M) that was connecting the two spatially separated aqueous feed (5mL containing 1M of metal ion solution) and receiving (10 mL of suitable stripping agent like dilute acid, dilute sodium fluoride and EDTA) solutions. The feed solution was maintained at an optimum pH of 3. The optimum pH of the feed solution was 3. It was found that the extraction efficiency for the different stripping agents followed the order of NaF>EDTA>HNO3and with NaF as stripping agent, the transport was achieved within 1 h. The studies were carried out in the presence of other ions and the interference from most of the ions could be effectively reduced using a masking agent in the feed.

Transport of p-nitrophenol in an agitated bulk liquid membrane system – Experimental and theoretical study by network analysis

A predictive mathematical model has been developed to simulate the pertraction of phenolic compounds in the agitated bulk liquid membrane system (ABLM). A bond-graph method, based on pseudo-thermodynamic network analysis, was applied for the detailed description of the three steps pertraction mechanism, i.e., extraction, diffusion, and re-extraction with the neutralization reaction in the stripping solution. The corresponding mathematical model (a set of ordinary differential equations) was solved to predict the time evolution of local fluxes and concentrations of p-nitrophenol (PNP) in the experimental system: PNP aq. soln.|tolunene|NaOH soln. The calculations were carried out mainly with the data accessible in literature (diffusion coefficients, thickness of diffusion layers) or measured in independent experiments (extraction and re-extraction kinetic constants, equilibrium distribution coefficient). The results of numerical calculations were compared with the experimental PNP transport data. It was found that the model and calculation procedures allow the prediction of time dependent-concentration or fluxes profiles of the transported species in the feed, membrane, and stripping solution as a function of operating parameters (volumes, concentrations), as well as pertraction mechanism parameters (distribution coefficients, diffusion coefficients, kinetic constants).

Operating Conditions of Hollow Fiber Supported Liquid Membrane for Phenol Extraction from Coal Gasification Wastewater

The extraction and recycling of phenol from high concentration coal gasification wastewater has been studied using polypropylene (PP) hollow fiber membrane and polyvinylidene fluoride (PVDF) hollow fiber membrane as liquid membrane support, the mixture of tributyl phosphate (TBP) and kerosene as liquid membrane phase, and sodium hydroxide as stripping agent in the process of extraction. The experiments investigated the effect of the operating conditions of the hollow fiber supported liquid membrane, such as aqueous phase temperature and the connection forms of membrane modules, on the extraction efficiency of phenol from high concentration coal gasification wastewater. The conclusions obtained from lab scale experiments provided guidance for scale-up experiments. So, in the scale-up experiments, three membrane modules connected in parallel, then three membrane modules connected in series were used to increase the treatment capacity and improve the treatment effect, under the operating conditions of wastewater temperature 20 ˚C, PH 7.5~8.1, flow rate 100 L/h and the concentration of stripping phase 0.1 mol/L, stripping phase flow rate 50 L/h, the extraction efficiency of the PP-TBP supported liquid membrane system was 87.02% and the phenol concentration of effluent was 218.14mg/L. And the phenol concentration of effluent met the requirements of further biodegradation treatment.

Demulsification of Emulsion Liquid Membrane Extracting Rare Earth Ions in Leaching Liquid of Phosphate Rock

This paper researched demulsification way for emulsion liquid membrane system extracting rare earth ions in leaching liquid of phosphate rock . Physical demulsification methods included heating, centrifugal, microwave. Chemical demulsification methods such as adding acid, alkal and inorganic salt were employed. The results showed that for Emulsion System A, the best way for demulsification was ultrasonic 30 min, 80 KHz sound intensity, 70°C ultrasonic temperature. The demulsification rate could reach 46% and concentration multiple of rare earth ions was 2 times. For Emulsion System B, centrifugal 90 min by 16000 r/min, the demulsification rate could reach the highest which was 52%, the concentration multiple of rare earth ions was 8 times.

Supported liquid membrane system for Cr(III) separation from Cr(III)/Cr(VI) mixtures.

This paper presents the results of analyses of the chromium(III) transport process from mixtures of Cr(III)/Cr(VI) ions using supported liquid membranes (SLM), in which dinonylnaphthalene sulfonic acid (DNNSA) and di(2-ethylhexyl) phosphoric acid (D2EHPA) were used as carriers. In both cases the membrane worked as a selective barrier for Cr(VI) ions. The increase in both the time of Cr(VI) ions-carrier interaction and the Cr(VI) concentration in the feed phase negatively influenced the Cr(III) separation. The polarizing layer consisting of Cr(VI) ions prevents the access of Cr(III) ions to the inter phase surface and leads to the deactivation of the carrier, which is the result of the strong oxidation properties of Cr(VI) ions. These factors meant that, in the case of the membrane with DNNSA, the membrane could not be used for the effective separation of Cr(III) from the Cr(III)/Cr(VI) mixture. On the other hand, the membrane with D2EHPA can be used for fast and efficient transport of Cr(III) ions, but only for strictly defined process parameters, i.e. where the level of chromium(VI) concentration is below 10(-3)M and with intensive feed phase mixing.

Cr(VI) transport via a supported ionic liquid membrane containing CYPHOS IL101 as carrier: System analysis and optimization through experimental design strategies

Chromium(VI) transport through a supported liquid membrane (SLM) system containing the commercial ionic liquid CYPHOS IL101 as carrier was studied. A reducing stripping phase was used as a mean to increase recovery and to simultaneously transform Cr(VI) into a less toxic residue for disposal or reuse. General functions which describe the time-depending evolution of the metal fractions in the cell compartments were defined and used in data evaluation. An experimental design strategy, using factorial and central-composite design matrices, was applied to assess the influence of the extractant, NaOH and citrate concentrations in the different phases, while a desirability function scheme allowed the synchronized optimization of depletion and recovery of the analyte. The mechanism for chromium permeation was analyzed and discussed to contribute to the understanding of the transfer process. The influence of metal concentration was evaluated as well. The presence of different interfering ions (Ca2+, Al3+, NO3−, SO42−, and Cl−) at several Cr(VI): interfering ion ratios was studied through the use of a Plackett and Burman experimental design matrix. Under optimized conditions 90% of recovery was obtained from a feed solution containing 7mgL−1 of Cr(VI) in 0.01moldm−3 HCl medium after 5h of pertraction.

English

Microbial fermentations are efficient alternatives to different manufacturing practices being followed for industrially important compounds like organic acids, food and pharmaceutically active products. However, the attractions offered by microbial processes are overshadowed by the costs associated with downstream processing involved in the recovery of pure products from such systems. Reduction of the cost in terms of financial and energy related inputs have been the goal of recent ongoing research in the field of bio-processing. This study has been focused towards development of an efficient method for simultaneous extraction of products from microbial fermentation. Through the study, the domain of liquid membranes and the possibilities of energy efficient extraction of microbial products from ongoing processes have been investigated. Liquid membrane system involves a liquid which is immiscible with the source and receiving solutions serves as a semi permeable barrier between these two liquid phases. The study uses a fumaric acid produced through fermentation of Rhizopus oryzae on Potato Dextrose Broth (PDB) under aerobic conditions as a model sample for extraction analysis. The culture media, that is presumably rich in fumaric acid and some other acidic products, has been subjected to extraction through liquid membrane based process. The reduction in concentration of sample used as source is measured titrimetrically. Thin layered chromatography has been deployed at certain instances for qualitative verification of the concentrations. The set up consisted of a modified layered 'liquid membrane’ setup for a ‘fumaric acid’ source, with toluene as organic membrane and sodium hydroxide as strip phase. The liquid membrane contained a carrier for assisted transfer and was agitated. Maximum extraction takes place during the first 20 to 30 min of the run as fumaric acid concentration falls to almost 40% of its initial concentration.   Key words: Fumaric acid, carrier, trioctylamine (TOA), liquid membrane, facilitated extraction.