Internal Stripping Phase Research Articles

Selective permeation of Ag+ ions from pyrosulfite solution through Nano-Emulsion Liquid Membrane (NELM) containing CYANEX 925 as carrier

A designed Nano-Emulsion Liquid Membrane (NELM) particles containing CYANEX 925 in kerosene as carrier, KSCN (potassium thiocyante) as internal stripping phase and span 80 as surfactant was prepared and used for the extraction of 9.27 × 10−4 M Ag+ from pyrosulfite (Na2S2O5) solution. The parameters affecting the liquid-liquid extraction of Ag+ such as [CYANEX925], [pyrosulfite] and temperature were separately investigated. Ammonium hydroxide and thiourea with different concentrations were used to enhance the extraction efficiency of Ag+. The batch results indicate that the addition of ammonium hydroxide as complexing agent increased the extraction efficiency of Ag+ with CYANEX 925 from Na2S2O5 solution (up to E% = 75) while the addition of thiourea inhibited and strongly decrease the extraction process (E% = 25). The emulsion membrane was prepared and the NELM particles were characterized using dynamic light scattering (DLS) which indicated that the obtained nanoparticles have an average particle size of 29.9 nm. The studied fundamental parameters affecting the emulsion liquid membrane stability indicated that the optimum conditions were: emulsification speed = 8500 rpm, emulsification time = 10 min, stirring speed = 400 rpm, Span 80 = 3.5 % (w/v), organic: internal phase = 1:1, ELM: aqueous phase = 1:10 and permeation time = 10 min. The chemical permeation rate was found to be independent of [KSCN] in the internal phase and also of [Ag+] concentration in the aqueous feed solution. The demulsification of silver ions permeated through the NELM was achieved with 1 M NaBH4. An application on the selective recovery of silver ions from leached pyrosulfite solution of X-ray films wasted from radiology centers was carried out using the prepared NELM containing CYANEX 925 as carrier.

Selective separation and enrichment of neodymium and gadolinium by emulsion liquid membrane using a novel extractant CYANEX® 572

In present study, the novel commercial extractant, CYANEX® 572, was applied for selective separation and enrichment of neodymium and gadolinium through an emulsion liquid membrane. Response surface methodology (RSM) based on central composite design (CCD) is carried out to explore the relationships between process variables namely, carrier concentration, initial pH of feed phase, surfactant concentration and mixing speed, and their interactions. The contours and 3D response surfaces of selective extraction of Gd(III) were achieved and significance of four important variables and their interactions on extraction efficiency of Gd(III) and Nd(III) and separation factor were found out. Also, three regression models for them were developed. A multiple optimization was performed to evaluate the best possible goals for the responses, simultaneously. Results indicated that the maximum separation factor of Gd(III) over Nd(III) was achieved using 0.75 M CYANEX® 572 as minimum concentration of carrier, initial feed pH of 1.56, surfactant concentration of 4% (v/v) and mixing speed of 135 rpm. Under the optimum condition, the extraction percentage of Gd(III) was maximum (67.45%), while the extraction percentages of Nd(III) was minimum (28.98) and the separation factor was found to be 3.78. Under the optimized condition, further experiments were conducted to investigate the effect of hydrochloric acid as internal stripping phase on the stripping efficiencies and enrichment factors were examined. At the internal concentration of 0.5 M, the stripping efficiency and enrichment factor reached the maximum of 89.04% and 12.01 for Gd(III), and 19.45% and 1.13 for Nd(III).

Investigating the performance of ELM systems in separating organic pollutants from industrial wastewater

Emulsion liquid membrane (ELM) is one of the processes widely used in industrial separation process. Extraction of benzoic acid from aqueous solutions by an emulsion type liquid membrane was investigated. The influence of two emulsion composition variables, namely the surfactant concentration, and organic phase to internal stripping phase ratio(VO/VI), as well as three process parameters, emulsion to external feed phase ratio (VE/VF), mixing speed of feed solution, and extraction time on the rates of extraction of benzoic acid, was experimentally studied. The emulsion liquid membrane consists of kerosene as solvent, Span 80 as surfactant, and NaOH as internal stripping phase. The role of a hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BMIM]+[NTf2]− in increasing the stability of the emulsion membrane was also studied. The stability of emulsion containing 0.2% (v/v) of [BMIM]+[NTf2]− has significantly increased in comparison with that without ionic liquid. Approximately 99.7% of benzoic acid was extracted after only 5min of contact with tested mixtures under the most favorable operating conditions.

Response surface optimization of kraft lignin recovery from pulping wastewater through emulsion liquid membrane process

Kraft lignin (KL) represents a key sustainable source of biomass for transformation into biofuels and high-value specialty chemicals. Excess lignin in pulping wastewater creates pollution problems, hence affecting human. Thus, the KL recovery from pulping wastewater by emulsion liquid membrane was investigated and optimized using response surface methodology in this study. The liquid membrane was prepared by dissolving carrier tricaprylylmethylammonium chloride (Aliquat 336) and hydrophobic surfactant sorbitan monooleate (Span 80) in kerosene (diluent) with sodium bicarbonate (NaHCO3) as the internal stripping phase and 2-ethyl-1-hexanol as the modifier. The comparison between the experimentally optimized, and the RSM optimized values was accomplished by optimizing the following parameters: carrier and stripping agent concentration and treat ratio of emulsion to feed phase. The maximum KL recovery of 97% was obtained under the optimum condition at 0.012M of Aliquat 336, 0.32M of NaHCO3, and 1:4.8 of treat ratio.

Emulsion liquid membrane for selective extraction of Bi(III)

Di(2-ethylhexyl)phosphoric acid was used as extractant of bismuth ions from nitrate medium by emulsion liquid membrane, with Triton X-100 as the biodegradable surfactant in n-pentanol bulk membrane. The novelties and innovative points of this work are the application of emulsion liquid membrane for selective and efficient extraction of bismuth ions as well as the relevant optimization procedures. The extraction of bismuth ions was evaluated by the yield of extraction. The experimental parameters were evaluated and optimized, including the ratio of di(2-ethylhexyl)phosphoric acid mass concentration to Triton X-100 (1.0%:0.5%), nature of diluent (n-pentanol), nature and concentration of stripping solution (sulfuric acid, 0.5mol·L−1), stirring speed (1800r·min−1) and equilibrium time of extraction (20min), initial feed solution of bismuth (350mg·L−1) and the volume ratio of internal stripping phase to membrane phase (14). The experimental parameters of kinetic extraction reveal that the bismuth ions can be extracted by 100%.

Emulsion liquid membrane for selective extraction of bismuth from nitrate medium

The novelty of this work is the selective extraction of bismuth ions from nitrate medium by emulsion liquid membrane. Di(2-ethylhexyl)phosphoric acid was used as extractant of bismuth ions from nitrate medium by emulsion liquid membrane, and Triton X-100 was used as the biodegradable surfactant in n-pantanol n-pentanol bulk membrane. The extraction of bismuth ions was evaluated by the yield of extraction. The experimental parameters were evaluated and were optimized. They included the ratio of di(2-ethylhexyl)phosphoric acid concentration to the concentration of /Triton X-100 concentration (1.0: 0.5% w/w), nature of diluents (n-pentanol), nature and concentration of the stripping solution (sulfuric acid, 0.5M), stirring speed (1,800 rpm) and equilibrium time of extraction (20min), initial feed solution of bismuth (350 ppm) and the volume ratio of the internal stripping phase to the membrane phase (14 times). The experimental parameters of kinetic extraction revealed that the bismuth ions were extracted at 100% 97%.

EMULSION LIQUID MEMBRANE PERTRACTION OF METAL IONS FROM AQUEOUS SOLUTIONS AND ELECTROPLATING EFFLUENT USING ROTATING DISK CONTACTOR

Removal of chromium (III), copper (II), and zinc (II) from synthetic aqueous solutions and electroplating wastewater by an emulsion liquid membrane technique (ELM) was studied using a rotating disk contactor (RDC). Kerosene as diluent, Span 80 as surfactant, di-(2ethyl hexyl) phosphate (D2EHPA) as carrier, and 1 N H2SO4 solution as internal stripping phase were used for emulsion preparation. RDC provides relatively low shear to emulsion and thus minimizes rupture of the ELM. Various hydrodynamic and chemical parameters such as metal ion concentration in the continuous (feed) phase, pH of the continuous phase, carrier concentration, agitation speed, internal stripping agent concentration, and flow rate ratio of continuous phase to dispersed phase (treat ratio) have been experimentally investigated. The results showed that it is possible to remove more than 95% of all metal ions from aqueous solutions with a concentration factor of more than 35 and a removal of 68–74% of three metal ions from the electroplating effluent.

Extraction of Arsenic(V) from Water Using Emulsion Liquid Membrane

In this article, the extraction of arsenic(V) from water by means of emulsion liquid membrane is investigated. The influence of operating factors such as stirring speed, concentration of sulfuric acid in the external aqueous phase, concentration of sodium sulfate in internal stripping phase, and concentration of carrier in the membrane phase on the extraction efficiency are investigated and their optimum values, which provide the maximum recovery of arsenic, are determined. Taguchi experimental design is used in order to reduce the number of experiments. The optimum amounts for the extraction of arsenic from water, based on the results, are: stirring speed, 500 rpm; concentration of sulfuric acid in the feed, 1.5 g mol/lit; concentration of reagent in internal phase, 1.5 g mol/lit; and concentration of carrier in 3 ml kerosene which is added to the membrane phase, 0.1 g mol/lit.

Extraction of Palladium from Acidic Chloride Media into Emulsion Liquid Membranes using LIX 984N-C<sup>®</sup>

The extraction of palladium from hydrochloric acid solutions into emulsion liquid membranes (ELMs) using LIX 984N-C as the extractant was investigated. The influential factors and the total capacities of palladium extraction were determined by a batch method. The behavior of palladium extraction by ELMs under the operational conditions-pH of the external feed phase, surfactant and extractant concentration, internal stripping phase concentration, treat ratio and agitation speed were reported. Using LIX 984N-C, palladium was effectively extracted from the external acidic chloride feed phase into the internal receiving phase of W/O emulsions. More than 92% of palladium could be extracted at a feed pH of 2 with 3% Span 80, 9% LIX 984N-C and 7M HCl at a stirring speed of 300 rpm.

Enriching chromium(III) from dilute aqueous stream via liquid emulsion membrane process

ABSTRACTWastewaters from many industrial processes often contain chromium(III) and chromium(VI) from metallurgical operations is highly toxic. The liquid emulsion membrane (LEM) process performs extraction and stripping simultaneously (eliminating the stripper entirely); this process intensification provides a significant increase in interfacial area for mass transfer. LEM process has been used for the enrichment of Cr(VI), but there is very little published information for the enrichment of Cr(III). In this study, the extraction and enrichment of chromium(III), using di‐2‐ethylhexyl phosphoric acid (D2EHPA) in dodecane was carried out via the LEM process with aqueous methane sulfonic acid (MSA) as the strip phase. The complexation stoichiometric coefficient and equilibrium constant were measured by conventional liquid–liquid extraction studies. Emulsion preparation parameters, such as carrier concentration, surfactant concentration, and internal strip phase (MSA) concentration, were determined in order to obtain the maximum extraction and enrichment. The influence of operating process parameters on the performance of the LEM process, i.e. residence time, speed of agitation and treat ratio (TR), were studied. It was found that 83% extraction and nearly nine times enrichment of chromium(III) was obtained within 6 min of residence time at 400 rpm and 1:10 TR. A simple, but practical, model was developed in order to assist process design studies. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Extraction performance of chromium (VI) with emulsion liquid membrane by Cyanex 923 as carrier using response surface methodology

Cr (VI) being a toxic and carcinogenic pollutant should be removed from industrial effluents. In the present investigation, Cr (VI) was transported selectively with Cyanex 923 carrier from bulk feed phase to internal stripping phase using emulsion liquid membrane technique. The liquid membrane was prepared by loading with Cyanex 923 as the carrier, Span 80 as the surfactant, kerosene as the solvent and sodium hydroxide as the stripping agent and their effect on the process parameters such as concentration of the surfactant, the ratio of organic phase to internal phase in the membrane and membrane to external phase ratio were studied using Box–Behnken design and response surface method. A quadratic polynomial regression equation was used to analyze the experimental data. The experimental and predicted values were in good agreement. The experimental results showed that chromium ion was extracted within 5 min. The chromium ion concentration was measured using inductively coupled plasma mass spectrometry (ICP-MS).

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. The maximum enrichment of Ru, obtained was almost 10.3 times, in the internal strip phase (2 mol L −1 of perchloric acid), from the feed phase containing Ru at 20 ppm level.

Extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membranes using TOPO as extractant

Experimental results for the extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membrane (ELM) using trioctylphosphine oxide (TOPO) as extractant are presented. The membrane phase consists of kerosene as diluent, TOPO as extractant, ECA 4360J (a nonionic polyamine) as surfactant and (NH 4) 2CO 3 solution as stripping phase. Effects of various parameters such as mixing speed, type and concentration of stripping solution, surfactant and extractant concentrations, and volume ratio of the membrane phase to internal stripping phase on Cr (VI) extraction were studied and optimum conditions were determined. Results show that with proper adjustment of experimental conditions for the extraction of Cr (VI) can be enhanced to a great extent. This study also examined the effects of concentrations of acid and metal ions in the feed phase for the extraction of Cr (VI) ions. The results also showed that by appropriate selection of the extraction and stability conditions, nearly all of the Cr (VI) ions (100–500 mg/L) present in the acidic feed solution containing 1000 mg/L from each of Cu (II), Zn (II), Co (II), Ni (II) and Cd (II) ions were extracted within a few minutes. Concentration variations of Cr (VI) and other ions in the acidic solutions were determined by atomic absorption spectrophotometry.

Emulsion liquid membrane pertraction of imidazole from dilute aqueous solutions by Aliquat-336 mobile carrier

This paper reports a study of batch extraction of imidazole from dilute aqueous solutions using an emulsion liquid membrane (ELM) technique. Capabilities of this method in the separation of solute from dilute aqueous solutions are shown. Studies on the extraction equilibrium between organic and aqueous phases were performed. Effects of various parameters such as agitation time, speed of emulsification, internal phase concentration, extractant concentration (carrier), volume ratio of organic phase to aqueous internal phase and concentration of surfactant on the membrane stability as well as contact time, stirring speed, feed concentration, pH of external phase and volume ratio of the emulsion phase to the aqueous external phase on pertraction performance were studied. The organic phase consists of kerosene and n-heptane as diluent, Aliquat-336 as extractant and sorbiton monooleate (Span-80) as surfactant. HCl solution is used as the internal stripping phase. The results showed that by appropriate selection of the extraction and stability conditions, the maximum recovery of imidazole from the feed were achieved within a few minutes. The influence of the HCl concentration on stripping efficiency was investigated.

Uranium(VI) extraction from chloride solution with benzyloctadecyldimethyl ammonium chloride (BODMAC) in a liquid membrane process

The recovery of uranium(VI) from chloride solution using a liquid emulsion membrane (LEM) technique was studied. The emulsion is constituted by the quaternary salt of benzyloctadecyldimethyl ammonium chloride (BODMAC, R4NCl) as a carrier, kerosene as organic diluent, Span 80 as emulsifying agent and 0.5 mol/l Na2CO3 as stripping phase. The important variables affecting the LEM permeation process such as the concentrations of extractant, internal strip phase, types of organic diluent, and the presence of magnesium chloride or magnesium sulfate were investigated. It was found that, at a given condition, the maximum extraction rate of uranium(VI) reached 80%. The emulsion was stable at low pH in the presence of certain amounts of electrolytes such as NaCl and MgCl2.

Liquid Emulsion Membrane (LEM) Process for Vanadium (IV) Enrichment: Process Intensification

A liquid emulsion membrane (LEM) system for vanadium (IV) transport has been designed using di‐2‐ethylhexyl phosphoric acid (D2EHPA), dissolved in n‐dodecane as carrier. The selection of extractant, D2EHPA, was made on the basis of conventional liquid‐liquid extraction studies. The work has been undertaken by first carrying out liquid‐liquid extraction studies for vanadium (IV) to get stoichiometric constant (n), and equilibrium constant (Kex), which are important for process design. Transport experiments were carried out at low vanadium (IV) concentration (ppm level). The studies on liquid emulsion membrane included i) the influence of process parameters i.e. feed phase pH, speed of agitation, treat ratio, residence time and ii) emulsion preparation study i.e., organic solvent, extractant concentration, surfactant concentration, internal strip phase concentration. When the strip phase concentration was 2 mol/dm3 (H2SO4) and feed phase pH 3 better extraction of vanadium was obtained. Higher Vm/V1 gave higher extraction of vanadium (IV). A simplified, design engineer friendly model was developed.

Extraction of chromium (VI) from sulphuric acid aqueous solutions by a liquid surfactant membrane (LSM)

Experimental results for the batch extraction of chromium (VI) from sulphuric acid aqueous solutions using a liquid surfactant membrane (LSM) are presented. Effects of various parameters such as time and speed of emulsification, internal phase concentration, extractant concentration, choice and concentration of surfactant, contact time, stirring speed, choice of diluent, and volume ratios of the membrane phase to internal stripping phase and that of the water-in-oil emulsions to the aqueous external phase on the membrane stability were studied. The membrane phase consists of hexane as diluent, tributyl phosphate, as extractant, and sorbiton monooleate (Span 80) as surfactant. A NaOH solution is the internal aqueous phase. Results show that with proper adjustment of experimental conditions the stability of the membrane can be enhanced to a great extent. This study also examined the effects of the concentrations of feed phase acid, metal ions, and carrier on the extraction of Cr(VI) ions. Further, the extraction kinetics of the metal ions by LSMs was examined. The results also showed that by appropriate selection of the extraction and stability conditions, nearly all of the Cr(VI) ions present in the continuous phase were extracted within a few minutes. The influence of the NaOH concentration on stripping efficiency was investigated.

Removal of Lead from Wastewater Using Emulsion Liquid Membrane Technique

A detailed study was conducted to remove lead from storage battery industry wastewater by using emulsion liquid membrane (ELM) technique. The storage battery industry wastewater has an initial lead concentration of 4.2 ppm (average) and a pH value of 1.4. Emulsion liquid membrane consisted of kerosene and mineral oil as organic solvents, sorbitan monooleate (Span 80) as a surfactant, di-2-ethylhexyl phosphoric acid (D2EHPA) as a carrier or extractant, and sulphuric acid (H2SO4) as a stripping agent. The important variables affecting the ELM systems, such as organic solvents, surfactant, and carrier concentrations, internal stripping phase normality, external aqueous phase pH value, and normality of organic ligand added, have been investigated systematically. The system which adjusted to a pH value of 4.0, obtained the maximum lead removal in first 5 min of the treatment studies and exhibited a low turbidity and swelling at the end of the experiment.

Batch extraction of gold(III) ions from aqueous solutions using emulsion liquid membrane via facilitated carrier transport

Experimental results for the batch extraction of gold(III) ions using an emulsion liquid membrane (ELM) with an internal alkaline aqueous sodium sulfite are presented. Experiments were performed using LK-80 as the biodegradable emulsifier for the first time in emulsion liquid membrane technology. The effects of various parameters, such as Au(III) concentration in the aqueous phase, concentration of carrier in the membrane phase, concentration of sodium sulfite in the internal stripping phase, pH of the external aqueous phase and the speed of agitation on the extraction rate were studied. Results showed that nearly all of the Au(III) ions in the aqueous phase were extracted in few minutes. By proper selection of the extraction conditions, almost all of the gold ions present in a concentrated feed solution were extracted within less than 25 min. A Taguchi analysis has been performed on the experimental results which determined the effects and contribution of each of the parameter on the extraction efficiency and interaction between the parameters.

Extraction of L-glutamic acid using emulsion liquid membrane

Extraction of L-glutamic acid using emulsion liquid membrane was carried out in a batch extractor. The emulsion was obtained using lubricating oil as solvent, 0.5 M HCl as internal stripping phase, IG2610E a nonionic and IG6000E an anionic surfactants as emulsifiers. Stability of emulsion was significantly affected by the volume of emulsifier and a stable emulsion was obtained for an emulsifier volume of 4% and 5% (v/v). The percentage reduction of solute in external phase depended on emulsion to external phase (M/E) ratio, agitator speed, and the pH of the external phase. The optimum M/E ratio, agitator speed, and pH for the maximum percentage reduction of solute and hence the extraction were 0.25, 150 rpm and 4.0, respectively, and under these conditions the maximum percentage reduction of solute in the external phase was 63.5. The data on percentage reduction of solute in external phase was related to agitator speed, M/E ratio, and pH of the external phase by regression analysis with an average absolute deviation of 15 percent.