- I am a researcher in the field of Radiochemistry, Physical chemistry (Separation science, solvent extraction, liquid ... moreI am a researcher in the field of Radiochemistry, Physical chemistry (Separation science, solvent extraction, liquid membrane separation).During the 1973-1989 was active in the undergraund Jewish movement in the USSR. Three years in in the Soviet GULAG.Worked (in USSR) on the nuclear production interprise (nuclear arms production). In Israel: in separation science and Technology.Resigned in 2002.edit
This chapter consists of the literature review devoted to the concepts used in the development of the competitive complexation/solvation theory (CCST). These are as follows: 1) Complexation through hydrogen bonding and proton transfer,... more
This chapter consists of the literature review devoted to the concepts used in the development of the competitive complexation/solvation theory (CCST). These are as follows: 1) Complexation through hydrogen bonding and proton transfer, chemical quantum mechanics;
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Publisher Summary The chapter gives an overview of the chemistry of metal solvent extraction; it provides the factors underlying the strength of metal extractant interactions, their influence for different metals and extracting reagents,... more
Publisher Summary The chapter gives an overview of the chemistry of metal solvent extraction; it provides the factors underlying the strength of metal extractant interactions, their influence for different metals and extracting reagents, and other parameters of complexation that are briefly reviewed and discussed. Solvent extraction of metals is an important technology in hydrometallurgical industry, analytical separations, and liquid waste treatment. Metal ions, cations, and anions are extracted from an aqueous phase into an organic phase through reversible chemical reactions, forming organic-soluble neutral complexes. Extractant usually has very low solubility in an aqueous phase, but interacts with metal ions and obtains high solubility in an organic phase complex. So, extraction is described by a heterogeneous chemical reaction on either side of the aqueous organic interface to the final equilibrium concentrations of the reaction product. In addition, the chemical reaction of solutes with organic compounds (termed as extractants, or reagents), dissolved in the organic solvent (diluent), is accompanied by the distribution of product complexes between two immiscible phases. The extent of complexation for any solute–ligand system is defined by equilibrium constant, which is termed stability or formation constant for metal–ligand interaction. Furthermore, the chapter explains metal extraction by anion exchangers and many equations.
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The competitive complexation/solvation theory is introduced to explain the mechanisms of solvent extraction of metals by acidic extractants.
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Selective removal of heavy metal ions from industrial wet-process phosphoric acid (WPA) was studied, using the two liquid membrane systems: Hybrid Liquid Membrane (HLM) and Aqueous Hybrid Liquid Membrane (AHLM). Monothiophosphinic acid... more
Selective removal of heavy metal ions from industrial wet-process phosphoric acid (WPA) was studied, using the two liquid membrane systems: Hybrid Liquid Membrane (HLM) and Aqueous Hybrid Liquid Membrane (AHLM). Monothiophosphinic acid (Cyanex 302) in kerosene (for the HLM) and Polyvinylsulfonic acid (PVSA) aqueous solution (for the AHLM) were used as a liquid membrane (LM), separated from the feed and strip streams by neutral or cation-exchange membranes. On application of the HLM separation system, the permeation from the feed to the strip phase followed the selectivity sequence: Zn >> Cd > Cu with all types of membranes used. Results show that the selective separation of Cd and Zn from the WPA may be achieved by the HLM with cation-exchange membranes, using a single set-up installation at continuous processing. Copper is accumulated in the Cyanex 302, poisoning the carrier. So, this carrier and HCl as a strip solution can not be recommended for the HLM processing of WPA....
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... VS Karasev, VS Kislik, GF Shred, and RV Grebennikov ... Curve 1 has eight well-resolved peaks (denoted by Roman numerals), enabling one to determine with sufficient accuracy the charac-teristic temperature of the corresponding stage... more
... VS Karasev, VS Kislik, GF Shred, and RV Grebennikov ... Curve 1 has eight well-resolved peaks (denoted by Roman numerals), enabling one to determine with sufficient accuracy the charac-teristic temperature of the corresponding stage of helium evolution. ...
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full... more
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Solvent extraction (SX) or liquid-liquid distribution1 techniques have a broad field of applications in inorganic and organic chemistry and large-scale industrial separations, in analytical chemistry, in pharmaceutical and biochemical... more
Solvent extraction (SX) or liquid-liquid distribution1 techniques have a broad field of applications in inorganic and organic chemistry and large-scale industrial separations, in analytical chemistry, in pharmaceutical and biochemical industries, and in waste treatment. In addition, SX is a good instrument for studying fundamental understanding of equilibrium and kinetics of complex formation processes. Extraction methods have now become a routine procedure in separation technologies. The literature volumes of publications on the subject, and the number of newly discovered extraction methods, increase every year. Many methods based on chelate extraction have been considered as routine practice. The hitherto unexplored potentialities are also very considerable. Extraction is a major tool in the study of the processes of complex formation and of the state of compounds in solution. This monograph differs in scope and approach from the recent books by Rydberg et al. and Ritcey (Rydberg ...
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Application of competitive complexation/solvation theory in metals solvent extraction: new opportunities in process development. Kislik, Vladimir. Casali Institute of Applied Chemistry, School of Applied Science and Technology, The Hebrew University of Jerusalem, Jerusalem, Israel. Editor(s): You...more
The competitive complexation/solvation theory of solvent extn. constitutes a general framework for interpretation and quantification of ion-mol. interaction data in extn. systems. Depending on extg. metal-solvent affinity const. and metal... more
The competitive complexation/solvation theory of solvent extn. constitutes a general framework for interpretation and quantification of ion-mol. interaction data in extn. systems. Depending on extg. metal-solvent affinity const. and metal concn. ratios, four possible stages of extn. behavior and interacting mechanisms are considered. Affinity const. ratios are easily acceptable through the independent measurements of three-component systems. Once detd. and tabulated, the affinity const. ratio data may be used in any system of interest. Math. descriptions of the results are introduced for different interactions. Active solvent (including water) concns. in the org. phase and temp. are included to the quant. consideration. The theory allows direct comparison of the complexing/solvating power (competition order) of various extractants, active solvents and diluents. As a result, predictions for the extn. effectiveness and selectivity are possible. Some metal extn. systems are analyzed on...
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ABSTRACT The paper discusses Pfaff’s proof of the Saalschütz summation, which actually preceded Saalschütz’ work by hundred years. Set S n (a,b,c)= 3 F 2 -n,a,b;1 c,1+a+b-c-n, and σ n (a,b,c)=(c-a) n (c-b) n (c) n (c-a-b) n . The... more
ABSTRACT The paper discusses Pfaff’s proof of the Saalschütz summation, which actually preceded Saalschütz’ work by hundred years. Set S n (a,b,c)= 3 F 2 -n,a,b;1 c,1+a+b-c-n, and σ n (a,b,c)=(c-a) n (c-b) n (c) n (c-a-b) n . The Saalschütz summation states S n (a,b,c)=σ n (a,b,c), and Pfaff proved it in the simplest possible way: showed that S n (a,b,c)-S n-1 (a,b,c) and σ n (a,b,c)-σ n-1 (a,b,c) admit the same recurrence. This Pfaffian approach is shown to be effective for Bailey’s, Dougall’s, Lakin’s and Kummer’s summation identities. It is noted that the Pfaffian approach seems most effective for balanced and well-poised hypergeometric series. It is often the case that the Pfaffian approach has to prove a cluster of related identities, and not just one of them.
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... VS Karasev, VS Kislik, GF Shred, and RV Grebennikov ... Curve 1 has eight well-resolved peaks (denoted by Roman numerals), enabling one to determine with sufficient accuracy the charac-teristic temperature of the corresponding stage... more
... VS Karasev, VS Kislik, GF Shred, and RV Grebennikov ... Curve 1 has eight well-resolved peaks (denoted by Roman numerals), enabling one to determine with sufficient accuracy the charac-teristic temperature of the corresponding stage of helium evolution. ...
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The modified competitive preferential solvaltion theory, together with the concepts of aggregation stages and amphoteric properties of extractants, are introduced to explain the mechanisms of solvent extraction. Four possible stages of... more
The modified competitive preferential solvaltion theory, together with the concepts of aggregation stages and amphoteric properties of extractants, are introduced to explain the mechanisms of solvent extraction. Four possible stages of extraction behavior, interacting mechanisms and aggregate structures formation, depending on solute-solvent affinity constant ratios and their concentrations, are discussed. Extractants are considered amphoteric and may perform as acids (electron acceptors) or bases (electron donors). A mathematical description for quantification of the results is also introduced. Based on the presented theory, analysis of different acid-amine and metal ion-organic acid extraction systems are presented. It gives a key for preliminary quantitative prediction of suitable extraction systems.
A novel competitive complexation/solvation theory has been developed for interpretation, simulation and preliminary quantification of extraction systems. This theory is based on the modified competitive preferential solvation theory, the... more
A novel competitive complexation/solvation theory has been developed for interpretation, simulation and preliminary quantification of extraction systems. This theory is based on the modified competitive preferential solvation theory, the concept of amphoteric properties of extractants and the concept of the formation of different aggregation structures on increasing extractant loading. The theory establishes correlation between complexation and solvation. Co-solvent independence allows direct comparison of the complexing/solvating power (competition order) of various solvents, used as extractants, enhancers (synergistic agents), and diluents. Once determined and tabulated, solute/solvent affinity constant ratio data may be used in any system containing these components. Mathematical descriptions of classical and the presented theories are compared and discussed. Some acid–amine extraction systems are analyzed based on the theory statements presented. The model provides a key for preliminary quantitative prediction of suitable extraction systems. Data, available from the literature and from experiments, were used.© 2003 Society of Chemical Industry
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Competitive complexation/solvation theory is used to interpret the influence of active solvents on solvent extn. of acids by amine-based extractants. This theory is based on the modified competitive preferential solvation theory, the... more
Competitive complexation/solvation theory is used to interpret the influence of active solvents on solvent extn. of acids by amine-based extractants. This theory is based on the modified competitive preferential solvation theory, the concept of amphoteric properties of extractants, and the concept of changing aggregation structures when extractant loading increases. Active solvent concn. parameter is introduced to the quant. consideration of the extn. systems. The paper discusses four possible stages of extn. behavior, interaction mechanisms, and aggregate structures formation, depending on solute-solvent affinity const. and concn. ratios. The influence of different types of active solvents in each stage is analyzed. Math. description is introduced for the quantification of results and process simulation. It gives a key for preliminary quant. prediction of suitable extn. systems
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The modified competitive preferential solvation (COPS) theory together with the concepts of aggregation stages and amphoteric properties of extractants are introduced to explain the mechanisms of solvent extn. of acids by different basic... more
The modified competitive preferential solvation (COPS) theory together with the concepts of aggregation stages and amphoteric properties of extractants are introduced to explain the mechanisms of solvent extn. of acids by different basic or mixed (acid-base, base-base) extractants. According to the modified COPS theory, the mols. of a solvent mixt. (extractant, diluent, adduct) compete for acid to the extent of their affinity to assoc. and be concd. The acid is partitioned among the solvent components. As a consequence, an actual value of a given property in mixed solvents can be calcd. from its values measured in pure solvent components. The theory establishes the connection between complexation and solvation. Four possible stages of extn. behavior and interacting mechanisms that depend on acid-solvent affinity const. ratios and acid concn. are discussed. At low or very low acid concns. in the org. phase, the acid-amine complex, surrounded by its solvation shell, forms a geometric structure that is denoted as a nucleus aggregate. When the acid concn. is increased, the nucleus aggregates interact and form linear or ringed (cyclic) aggregates. At high acid concn. the linear (planar) aggregates eventually undergo a structural reorganization to form micelle-like or cross-linked cluster-like assocn. structures (as a rule, forming a so-called third phase). Extractants are considered amphoteric and may perform as acids (electron acceptors) or bases (electron donors), depending on the structure of their functional groups and compn. of the org. phase and on the structure of the solutes and compn. of the aq. phase. A math. description for result quantification is also introduced. On the basis of the presented theory, anal. of different extn. systems are discussed and some predictions are made.
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A hybrid liq. membrane system was developed for the sepn. of solutes such as metal ions. The system utilizes a soln. of an extn. reagent flowing between membranes. The membranes, which sep. the carrier soln. from feed and receiving... more
A hybrid liq. membrane system was developed for the sepn. of solutes such as metal ions. The system utilizes a soln. of an extn. reagent flowing between membranes. The membranes, which sep. the carrier soln. from feed and receiving solns., enable the transport of solutes but block transfer of the carrier to the feed or to the strip. Blocking the carrier is achieved through membranes hydrophilic/hydrophobic or ion exchange properties, or through their retention abilities due to pore size. The HLM-facilitated transport mechanisms have been schematically described, and theor. models have been developed to predict the rate of transport in the different sepn. processes. The model was tested on Ti(IV) transport from HCl solns. Ti was removed by counter-transport from low acidic pH 0.65 solns. or by co-transport from high acidic 7 mol/kg HCl solns. by using DEHPA in benzene as a liq. carrier membrane soln. The efficiency of Ti transfer was studied as a function of feed, carrier and strip flow rate. Mass transfer parameters obtained were compared with model calcd. data. Module optimization characteristics are discussed
Ti(IV) transport through a hybrid liq. membrane and supported liq. membrane systems was studied. A 1 mol/kg di-(2-ethylhexyl) phosphate or a mixt. with mono-(2-ethylhexyl) phosphate (I) in benzene was used as a carrier, impregnated into... more
Ti(IV) transport through a hybrid liq. membrane and supported liq. membrane systems was studied. A 1 mol/kg di-(2-ethylhexyl) phosphate or a mixt. with mono-(2-ethylhexyl) phosphate (I) in benzene was used as a carrier, impregnated into the membrane in the SLM or as a bulk carrier soln. between membranes in the HLM. Celgard 2400 25 m thick and Celgard 2402 50 m thick hydrophobic microporous polypropylene films were used as the SLM support. The same hydrophobic membranes, hydrophilic Celgard 3400 25 m thick, cation-exchange Neosept CM-1, anion exchange Neosept ACH-45 membranes were used as barriers in the HLM system. A 0.1 mol/kg Ti(IV) HCl at pH 0.65 and at 7 mol/kg HCl were studied as a feed phase. The receiver/strip phase was a 2 mol/kg HCl soln. The Ti transport rate through the SLM from low and high acidity feed is found in the range of 3-410-6 mol/m2-s. Preloading of the carrier by 0.08 M Ti(IV) before impregnation shows a two-fold increase in transport rate from the high-acidity feed. The rate-controlling step of the transport is the kinetics of a back-extn. process. I, a strong complexant of Ti, in the carrier leads to a drastic decrease in the transport rate. Elution of the carrier soln. from the support and gel layer formation on the strip phase exit of the membrane is the main disadvantage of the SLM system for application in Ti sepn. The Ti transport rate through the HLM with hydrophobic membranes is close to that in the SLM. Preloading by 0.08 M Ti of the initial carrier phase leads to a 6-fold increase of the Ti flux from the high acidity feed. I as an additive to the carrier leads to fouling of the membrane. The rate-controlling step of the transport is the resistance of the feed phase inside the pores for ion-exchange membranes, competing with the back-extn. kinetics. Elimination of the carrier phase elution from the membrane pores and of membrane fouling at the same or close mass transfer rates, are decisive advantages of the Ti sepn. processing by the HLM in comparison with SLM
A novel aq. hybrid liq. membrane (AHLM) system comprising three sep. aq. liq. phases was developed for the sepn. of solutes, such as metal ions and acids. Water-sol. polyelectrolytes were used as carriers in aq. membrane solns., sepd.... more
A novel aq. hybrid liq. membrane (AHLM) system comprising three sep. aq. liq. phases was developed for the sepn. of solutes, such as metal ions and acids. Water-sol. polyelectrolytes were used as carriers in aq. membrane solns., sepd. from the feed and strip streams by charged membranes. Sepn. of metal cations was tested in the AHLM system consisting of aq. polyanion solns. (polyvinylsulfonic acid, PVSA, or its sodium salt), as the liq. membrane phase, and cation-exchange membranes as barriers between the phases. While treating an aq. soln. contg. a mixt. of copper and cadmium salts, high selectivity to copper (>20) was found, combined with relatively high transport rate (3.5 10-6 mol/m2 s). The sepn. of anions was tested in AHLM systems contg. aq. solns. of branched polyethylenimine (BPEI) as the membrane phase. Anion-exchange membranes were used as barriers between the phases. While treating aq. solns. contg. copper and cadmium in their anionic complex form, high selectivity to cadmium was found. The transport rate of Cu was about three orders of magnitude lower than that in the case of PVSA liq. membrane. In the sepn. of carboxylate anions, BPEI carrier shows relatively low selectivity: SLa/Ac = 1.7 and SCit/La = 2.8. The transport rate of lactate is 2.6 10-5 mol/m2 s. Transport mechanisms are discussed for all these AHLM systems. AHLM solve most of the problems assocd. with other types of liq. membranes. Since the membrane is stable and no org. solvent is used, there is no contamination of the feed and strip (product) phases. Higher selectivities and transport rates are attainable.