Extraction rate of palladium using divinylbenzene microcapsules containing tri-n-octylamine as the extractant

The extraction of palladium(II) from an aqueous hydrochloric solution was carried out using divinylbenzene microcapsules containing tri-n-octylamine as the extractant. The preparation of these microcapsules was affected by the preparation conditions, such as the concentrations of the divinylbenzene, tri-n-octylamine and diluent. In the case of extremely low or high concentrations of divinylbenzene, and for the high concentration of tri-n-octylamine, the matrix-type microcapsules could not be prepared. The morphologies the prepared of microcapsules were spherical and the surface of the microcapsules was very smooth. The adsorption of palladium(II) onto the microcapsules was negligible compared to the extraction of palladium(II), and it found that the adsorption of palladium(II) onto the microcapsules did not occur. The extraction of palladium(II) into the microcapsules was affected by the characteristics of microcapsules such as, the surface area, pore diameter and volume, and the encapsulation efficiency of the tri-n-octylamine. The extraction of palladium(II) into the microcapsules seemed to have three steps. The first extraction step is caused by the tri-n-octylamine existing near the surface of the microcapsules. The second step is caused by the internal diffusion. The final step is the extraction equilibrium. Based on these results, the microcapsule that has a high encapsulation efficiency of tri-n-octylamine and small pore diameter seems to show the high extraction performance.     

Supported Liquid Membranes Extraction of W(VI) Ions from HCL Solutions Containing Tartaric Acid

Abstract

A transport study of W(VI) ions across tri-n-octylamine (TOA) xylene-based supported liquid membranes from aqueous solutions containing tartaric acid (TA) has been carried out. TA complexes with W(VI) ions to keep them in solution and enhance flux. The optimum conditions of transport found are 0.132 M TA and 0.001 M HCl in the feed, 3.7 M NaOH in the strip, and 0.66 M TOA in the membrane. Beyond these TA and TOA concentrations, there is a decrease in flux and permeability values which are 4.76 × 10^?5 mol/m²/s and 9.15 × 10^?10 m²/s, respectively. NaOH is a better stripping agent than NH₄OH for these metal ions. Increases in membrane phase viscosity and temperature reduce the values of these transport parameters.     

Study of Soluble Tungstate Species by Solvent Extraction

Abstract

Tungsten is extracted from acidic tungstate solutions by the long-chain tertiary alkyl amine, tri-n-caprylamine, in benzene. Distribution data derived from solvent extraction are interpreted in terms of the predominating tungsten species present in the aqueous phase. The results show that the nature of the tungstate species extracted by tri-n-caprylamine changes markedly with the pH of the system. Further, the order of extraction is consistent with the order in which tungstate species should form as a function of the ratio of acid equivalents to moles of tungstate ions in solution.     

Modeling of Amine-Facilitated Liquid Membrane Transport of Binary Organic Acids

ABSTRACT

The transport rates of lactic and citric acids from binary solutions across supported liquid membranes containing tri-n-ocytylamine are measured. A mass transfer model is proposed which considers aqueous film diffusion, interfacial chemical reaction, and membrane diffusion. It is shown that the difference between the measured and modeled rates was more significant at high total acid and amine concentrations. This could be partly due to the ignorance of mutual interactions between the acids in the aqueous phase and the complexes in the membrane phase in this model (chemical effect), and to limited validity of “fixed” transport properties over a rather wide concentration range (mechanical effect).     

Facilitated Transport of Zinc Chloride through Hollow Fiber Supported Liquid Membrane. Part 1. Transport Mechanism

Abstract

The facilitated transport of zinc chloride through a liquid membrane of tri-n-octylamine dissolved in n-dodecane with 2-ethylhexyl alcohol, supported on a microporous polyethylene hollow fiber, has been studied in a series of three papers. This first paper deals with the transport mechanism. The distribution of zinc chloride between the liquid membrane phase and the aqueous hydrochloric acid solution was clarified. The characteristics of the support membrane and of the flow system were examined through phenol transport experiments. The initial permeation rate of zinc chloride was explained by the sum of film resistances in the two aqueous phases and a membrane phase resistance     

Separation of Osmium(VIII) from Platinum Group Metals by Extraction with Liquid Ion Exchangers

Abstract

A method is developed for the extraction and separation of osmium from palladium, platinum, ruthenium, rhodium, and iridium with tri-n-octyl amine either from hydrochloric or hydrobromic acid solutions. The extracted species is (R₃NH⁺)₂OsCl₆ ^2-. The method is shown to be applicable to synthetic mixtures.     

Extraction of Sulfuric Acid in the Tri-n-caprylamine-Benzene System

Abstract

Solvent extraction, molecular weight determination, and infrared analysis have been used to study the nature of the amine salt present in the organic phase in the extraction of sulfuric acid by tri-n-caprylamine. Tri-n-capryl-amine in the concentration range of 0.05–0.25 M extracts sulfuric acid to form either the normal sulfate or the bisulfate salt, depending on the concentration of acid in the aqueous phase. The normal sulfate is monomeric, while the bisulfate is dimeric. Characteristic infrared absorption bands, attributable to the normal sulfate and the bisulfate salt form, were observed.     

Caprolactam recovery by a column packed with polysulfone microcapsules containing 1-octanol

Caprolactam recovery from its dilute aqueous solution is a challenging task in industry. To save resources and protect environment, a caprolactam recovery technology based on extractant microcapsules as the separation material was introduced. In this new technology, polysulfone microcapsules containing 1-octanol were packed in a column. In the extraction process, recovery ratio of 0.99 was achieved within 0.6 bed volume. More than 10 theoretical plates per meter microcapsule column were realized. In the regeneration process, sulfuric acid aqueous solution was introduced as the stripping agent. Accordingly the new technology can be integrated with existing caprolactam production process because the eluent could be returned to NH₃ causticization section. Caprolactam was successfully stripped and concentrated. Caprolactam concentration of 112 g/L in the eluent was obtained. New technology based on extractant microcapsules shows high efficiency in caprolactam recovery.     

The extraction of uranium (VI) and thorium (IV) from nitric acid solutions by tri-n-octyl phosphine oxide

The distribution of uranium(vi) and thorium(iv) between nitric acid solutions and solutions of tri-n-octyl phosphine oxide (TOPO) in kerosene has been investigated. The organic phases have been studied by infrared and nuclear magnetic resonance spectroscopy. Further the absorption spectra of both the aqueous and organic phases have been examined in the extraction of uranium(vi).     

The extraction of lactic acid by emulsion type of liquid membranes using alamine 336 in escaid 100

The extraction of lactic acid from aqueous solutions through an emulsion liquid membrane containing Alamine 336 as carrier was investigated. The influence of mixing speed, diluent type, surfactant concentration, extractant concentration, feed solution pH, stripping concentration, phase ratio, and feed concentration were examined. Liquid membrane consists of a diluent (n‐heptane, toluene, kerosene, Escaid 100, and Escaid 200), a surfactant (Span 80) and an extractant (Alamine 336), and Na₂CO₃ were used as a stripping solution. It is possible to extract 91% of lactic acid from aqueous solutions using Alamine 336 in Escaid 100, as an extractant and a diluent respectively.     

Coupled transport of Pb2+ through tri‐n‐octylamine‐xylene‐polypropylene supported liquid membranes

Transport of Pb²⁺ was carried from acidic solution into alkaline stripping phase through tri‐n‐octylamine‐xylene‐polypropylene supported liquid membrane. The transport of Pb²⁺ through the membrane was studied by varying the concentration of Pb²⁺ and HNO₃ in feed solution, NaOH concentration in strip solution and TOA concentration in membrane phase. The flux data obtained has been used to study the stoichiometry of complex Pb(NO₃)_n+2(HNR₃)_n. The supported liquid membrane (SLM) has been found stable for 10 runs with 24 h between each run. This SLM has been used effectively to extract lead ions along with chromium, copper and zinc ions from aqueous acidic leached solution of paint and industrial effluents. © 2012 Canadian Society for Chemical Engineering     

Speciation of Molybdenum (VI) In Aqueous and Organic Phases of Selected Extraction Systems

Abstract

The extraction study of molybdenum (VI) by 30% tri-n-butyl phosphate in n-dodecane and 0.2 M octyl (phenyl)-N,N-di-isobutylcarbamoylmethylphosphine oxide in 30% tri-n-butyl phosphate extraction systems was performed from aqueous solution containing HCl, HNO₃ and acetohydroxamic acid. Depending on extraction conditions, acetohydroxamic acid can significantly affect the speciation of molybdenum and can increase or decrease its distribution ratio. Our investigation confirmed the strong ability of the acetohydroxamic acid to form complexes with Mo even in highly acidic solutions. UV absorption spectra confirmed that a fraction of the Mo(VI)-AHA species can be present in the organic phase after extraction.     

Extraction of Uranium from “Abu-Tartur” Phosphate Aqueous Leachate Solution

Abstract

Uranium was effectively extracted from a synthetic aqueous monocalcium phosphate/phosphoric acid mixture (MCP/H₃PO₄) by tri-n-octylamine dissolved in different solvents and the presence of low concentrations of some counteranions (oxalate, citrate, chloroacetate) in the aqueous phase. The extraction efficiency was markedly enhanced by the salting out action of the concentration of calcium ions in the MCP/H₃PO₄ solution.     

Development of a Spiral-Type Flowing Liquid Membrane Module with High Stability and Its Application to the Recovery of Chromium and Zinc

Abstract

A new type of liquid membrane named a “flowing liquid membrane” is proposed. In this type of liquid membrane, a liquid membrane solution containing a carrier flows in thin channels between two hydrophobic micro-porous membranes which separate the membrane solution from a feed and a strip solution, and forms a stable liquid membrane. The flowing liquid membrane was made into a spiral-type module, and experiments on the separation and enrichment of Cr(VI) in aqueous solutions were performed with the flowing membrane module using tri-n-octylamine as the carrier. It was found that this type of module has high stability as well as high performance, and Cr(VI) was successfully removed and concentrated from its dilute solutions. The result on the recovery of zinc using di(2-ethylhexyl)phosphoric acid as the carrier is also presented.     

Experimental and modeling study for the removal of formic acid through bulk ionic liquid membrane using response surface methodology

Abstract

In this study, formic acid removal from its aqueous solutions through bulk ionic liquid membrane (BILM) was investigated. Tributyl phosphate (TBP) as a carrier in imidazolium-based ionic liquids was used. D-optimal design based on response surface methodology has been applied to investigate the effect of various operating factors. Initial formic acid concentration, TBP concentration, and NaOH concentration were selected as numerical factors, and ionic liquid type was chosen as a categorical factor. The model equations were obtained to determine BILM process behavior. The removal efficiencies, represented by the extraction and stripping efficiencies, were calculated from the experimental data. The highest removal efficiencies were determined at higher concentration values of TBP and NaOH. All ionic liquids studied in this study had good transport selectivity for the removal of formic acid. The design study showed that BILM is an effective method for the removal of formic acid from the water.     

A Double Liquid Membrane System for the Removal of Actinides and Lanthanides from Acidic Nuclear Wastes

Abstract

Supported liquid membranes (SLM), consisting of an organic solution of n-octyl(phenyl)-N, N-diisobutylcar-bamoylmethylphosphine oxide (CMPO) and tributyl-phos-phate (TBP) in decalin are able to perform selective separation and concentration of actinide and lantha-nide ions from aqueous nitrate feed solutions and synthetic nuclear wastes.

In the membrane process a possible strip solution is a mixture of formic acid and hydroxylammonium formate (HAF). The effectiveness of this strip solution is reduced and eventually nullified by the simultaneous transfer through the SLM of HNOs which accumulates in the strip solution. A possible way to overcome this drawback is to make use of a second SLM consisting of a primary amine which is able to extract only HNO₃ from the strip solution.

In this work the results obtained by experimentally studying the membrane system: synthetic nuclear waste/CMPO-TBP membrane/HCOOH-HAF strip solution/ primary amine membrane/NaOH solution, are reported. They show that the use of a second liquid membrane is effective in controlling the HN0₃ concentration in the strip solution, thus allowing the actinide and lanthanide ions removal from the feed solution to proceed to completion.     

Supported Liquid Membrane Extraction Study of (MoO4)2- Ions using Tri-n-octylamine as Carrier

Abstract

The transport of (MoO₄)^2- ions across a tri-n-octylamine (TOA) xylene-based supported liquid membrane has been studied at various HCl concentrations in the feed, TOA concentrations in the membrane, and NaOH concentrations in the strip solution. The distribution coefficient and flux of the Mo(VI) ion species vary with the HCl concentration, indicating that different polymeric species of this metal ion are present in the aqueous solution. A TOA concentration increase of up to 1.308 mol/dm³ enhances flux and permeability of this metal ion, which beyond this concentration is reduced due to an increase in carrier liquid viscosity. An increase in NaOH solution concentration has been found to increase flux and permeability values. The continuous increase in pH of the feed with the transport of metal ions indicates that the (MoO₄)^2- transport does not involve a decrease or increase in concentration as a result of association of lower to higher or decomposition of higher to lower metal ions polymeric species. The optimum conditions of transport of Mo(VI) metal ions across these membranes have been found to be HCl = 0.01, [NaOH] = 1, and [TOA] = 1.308, furnishing flux and permeability values of the order of 2.49 × 10^?4 mol·m^?2·s^?1 and 2.32 × 10^?10 m²·s^?1, respectively.     

Column Sorption of Citric Acid from Aqueous Solutions Using Tri-n-octylamine-Impregnated Macroporous Resins

Abstract

Column sorption of citric acid from aqueous solutions using tri-n-octylamine (TOA)-impregnated macroporous resins was studied at 298 K. The breakthrough curves were measured as a function of the feed flow rate, citric acid concentration in the feed solution, TOA concentration in the resin phase, and type of resin. It was found that the type of resin played a most important role in determining the saturated capacity under comparable conditions. The desorption of citric acid from loaded resins was also evaluated with various eluants, including HCl, HNO³, H²SO⁴, and Na²CO³     

Synergistic Effects in the Extraction of Uranium(VI) by Di-4-octylphenyl Phosphoric Acid

Abstract

The extraction of uranium(VI) from sulfuric acid solutions by di-4-octylphenyl phosphoric acid (DOPPA) is enhanced by the addition of neutral organophosphorus compounds due to synergistic action. The effect of tri-n-butyl phosphate (TBP), dibutylbutyl phosphonate (DBBP), and tri-n-octyl phosphine oxide (TOPO) was studied. The synergistic effect increased in this order. In the case of TBP and DBBP the extraction coefficient for U(VI) decreased with increasing concentration of synergistic agent after reaching a maximum. With TOPO, on the other hand, there was an increase even after this limit. This was because of the extraction of uranium by TOPO itself. The effect of uranium loading in the organic phase on the synergistic behavior was studied and the results were compared with those obtained with di-2-ethylhexyl phosphoric acid (DEHPA) in the presence of the same synergistic agents. The results with these two extractants indicate that with TOPO the synergism is mainly due to the formation of substitution products of the type UO₂A₂B₂ and with TBP addition products of the type UO₂(HA₂)₂B.     

Performance of hollow fiber supported liquid membrane on the extraction of mercury(II) ions

The extraction and recovery or stripping of mercury ions from chloride media using microporous hydrophobic hollow fiber supported liquid membranes (HFSLM) has been studied. Tri-n-octylamine (TOA) dissolved in kerosene was used as an extractant. Sodium hydroxide was used as a stripping solution. The transport system was studied as a function of several variables: the concentration of hydrochloric acid in the feed solution, the concentration of TOA in the liquid membrane, the concentration of sodium hydroxide in the stripping solution, the concentration of mercury ions in the feed solution and the flow rates of both feed and stripping solutions. The results indicated that the maximum percentages of the extraction and recovery of mercury ions of 100% and 97% were achieved at the concentration of hydrochloric acid in the feed solution of 0.1 mol/l, the concentration of TOA at 3% v/v, the concentration of sodium hydroxide at 0.5 mol/l and the flow rates of the feed and stripping solutions of 100 ml/min. However, the concentration of mercury ions from 1–100 ppm in the feed solution had no effect on the percentages of extraction and recovery of mercury ions. Thus, these results have identified that the hollow fiber supported liquid membrane process has high efficiency on both the extraction and recovery of mercury (II) ions. Moreover, the mass transfer coefficients of the aqueous phase (k _i ) and membrane or organic phase (k _m ) were calculated. The mass transfer coefficients of the aqueous phase and organic phase are 0.42 and 1.67 cm/s, respectively. The mass transfer coefficient of the organic phase is higher than that of the aqueous phase. Therefore, the mass transfer controlling step is the diffusion of the mercury ions through the film layer between the feed solution and the liquid membrane.