LIQUID-LIQUID EXTRACTION OF Ag(I), Hg(II), Au(III) AND Pd(II) BY SOME OLIGOTHIA MACROCYCLIC LIGANDS INCORPORATING AROMATIC AND HETEROAROMATIC SUBUNITS*

ABSTRACT

A series of hydrophobic tri- to hexa-dentate sulfur containing macrocyclic ligands incorporating aromatic and heteroaromatic subunits have been studied with respect to their extraction properties toward Ag(I), Hg(II), Au(III), and Pd(II) in aqueous//organic systems. The stoichiometry of extracted species and their extraction constants have been determined. The different ligands are compared with structure related open-chain compounds. The influence of substitution, solvent, and anion on the extraction equilibrium is also discussed providing a basis for future design of selective extractants and for die development of improved separation methods. The extractability of the various metal ions strongly depends on the nature and the number of donor atoms of the corresponding ligands and on the properties of the metal ion itself. In some cases, simple open-chain ligands show extraction properties comparable to the present macrocycles. A trithia crown with incorporated benzo subunit highly prefers Ag(I) to Hg(II). Furthermore a distinct selectivity for Au(ni) and Hg(II) over Pd(II) with pyridine substituted macrocycles was found.     

LIQUID-LIQUID EXTRACTION STUDIES OF METAL IONS WITH DIAZACROWN AND STRUCTURE ANALOGOUS OPEN-CHAIN COMPOUNOS

1,10-diaze [8]crown-6, their N,N'-dibutyl- and dioctyl-substituted derivatives and the structure analogous open-chein tetreoxedieza slkanee have been synthesized in order to examine the extraction properties for Na⁺, K⁺, Sr²⁺ and Hg²⁺. It wes found, that the extraction of strontium, potassium and sodium picratee with azacrown compounds ie much higher than that with open-chein oxaaze alkanes. 1,10-diaze [18] erown-6 has a good selectivity for the extraction of Sr²⁺ over K⁺ and Na in alkaline solution. In the case of Sr²⁺ the diffarencea between tha various azacrown compounds are email, whereea in the caee of K⁺ and Na the substituted derivativee are better extractante. Theserssulte correspond qualitativsly with tha order of stebility conetantB in protic solvsnts. The extrectebility of N,N'-dioctyl-l, 10-dieze[18]crown-6 for HgCl₂ is very high. Contrerv to the order of stability conetants the uneubetituted conpound do not extract mercury under the choeen experimental condition*. The extraction power of open-chain conpounde ie aleo high and strong Influenced by the alkyl eubatltuente at the nitrogen donor stons,     

Physicochemical studies on the water-yeast cells-gas-oil system

Physical characteristics of the hydrocarbon fermentation broth obtained during the microbial synthesis of protein concentrates from mineral oil have been studied. The effect of pH and the action of electrolytes and various organic compounds on the stability of the emulsion were investigated. It has been possible to obtain a fairly stable emulsion containing more than 85% of oil in the internal phase by the use of dry yeast cells. The strong hydrophilic character of the yeast cell membrane and the lowering of interfacial tension between the mineral oil and water are responsible for the unique stability.     

HEAVY METAL EXTRACTION WITH THIOCARBAMIC-O-ALKYLESTERS

ABSTRACT

Two types of thiocarbamic-O-alkylesters, four bidentate ligands HL and one bis-bidentate ligand H₂L, were used as extractants for heavy metal ions from aqueous solutions. Silver(I) was extracted as neutral complexes in a yield > 99 %. The underlying stoichiometry and the extraction constants are discussed. The extraction of silver&I) by the bis-bidentate ligand is significantly more effective than the extraction by the analogous bidentate compound. In a dioxane/water mixture neutral, cationic and anionic silver complexes were found by means of pAg and pH potentiometric titrations. The extraction behavior is discussed with regard to the calculated stability constants.     

Sulfur containing noncyclic and macrocyclic ligands for the complexation of Ag+ in acetone and propylene carbonate

Complex formation between silver(I) and noncyclic and macrocyclic ligands containing sulfur donor atoms was studied in propylene carbonate and acetone as solvents. Stability constants and reaction enthalpies were measured by means of potentiometric and calorimetric titrations. The noncyclic ligand with nitrogen and sulfur donor atoms forms a more stable complex than the dithiacrown ethers. With increasing ring size of the crown ethers the stability constants and the values of the reaction enthalpy increase. The values of the reaction entropy are nearly constant.     

Thermodynamics of complex formation: nickel—caprolactam system

Polarographic techniques have been used to investigate the complexing reactions in aqueous solution between ε-caprolactam and nickel ion. The coordination number and stability constants of the complex have been determined polarographically. The method of Ringbom and Eriksson using cadmium as indicator ion was used on the basis of reversible and irreversible character of electrode reactions at dropping mercury electrode. The stability constants obtained at various temperatures were used to calculate various thermodynamic functions by graphical method.     

正辛醇为稀释剂条件下二元羧酸的萃取平衡特性

以二元羧酸乙二酸、丙二酸、丁二酸、顺丁烯二酸和苹果酸为分离对象,三烷基氧膦（TRPO）为络合剂,正辛醇为稀释剂进行了系统的萃取相平衡实验.结果表明,溶质的pK_a1和羧酸的亲油性同时影响络合萃取平衡.红外光谱分析表明,萃取剂TRPO与正辛醇之间形成氢键,抑制了对羧酸的萃取,使得TRPO与有机羧酸之间形成1∶1的络合物;负载有机羧酸的红外谱图表明,TRPO萃取有机羧酸为氢键溶剂化历程,负载有机羧酸的TRPO中的P=O键吸收峰的位移与有机羧酸的酸性有关.采用质量作用定律分析方法建立了负载量的表达式,模型拟合精度令人满意.     

Synthesis and ion binding properties of polyesters and polyamides with diazacrown-ethers

The synthesis of polymers containing a [22] diaza-crown-ether in the backbone is described. These compounds are obtained by polycondensation of N, N′-diethylene amine and N, N′-diethylene alcohol derivatives of the cyclic diamine [23] with various acid dichlorides, leading to polyesters and polyamides. The cation binding properties of these polymers are studied by water-chloroform extraction using picrate salts, and compared with the properties of the analogous monomeric molecules. The binding properties are strongly dependent on the polymeric structure and comparison with the analogue molecules clearly demonstrates that the observed decrease in complex stability is due mainly to the presence near the rings of ester or amide groups. An intramolecular structure is proposed, based on interactions between the nitrogen bridges and the ester or amide groups which lead to the formation of a five-membered ring.     

Silver electrowinning from silver(I)–calixarene complexes by two-phase electrolysis

Results are reported, providing the basis for an elegant new process for metal recovery from acidic solutions, by integrating solvent extraction (SX) and electrowinning (EW) in a single process, rather than operating them separately, as in conventional SX–EW processes. Calixarene-tetramide and its thio-analogue were used for the extraction of silver(I) ions from aqueous phases into dichloromethane, both compounds achieving extraction efficiencies >90%. The effects were determined of extractant and silver(I) concentrations, aqueous phase pH, and the presence of sodium ions, on the distribution of Ag(I) between aqueous and organic phases. Due to the impossibility of stripping the extracted metal conventionally, electro-reductive stripping of silver(I) from the loaded organic phase was carried out in the calixarene/nitric acid two-phase system. The effects were also investigated of current density or electrode potential on silver deposition current efficiencies and cell voltages. Based on experimental data, a new process for silver(I) removal from very dilute solutions was proposed that showed high percentage extractions of silver(I) from the aqueous phase, coupled to direct EW of silver from the calixarene complex in the loaded organic phase, regenerating the extractant for recycle. Current efficiencies in the range from 60% to 90% and cell voltages <3.5 V were achieved simultaneously in this process.     

SOLVENT EXTRACTION EQUILIBRIA OF LEAD(II) WITH ACIDIC ORGANOPHOSPHATE AND PHOSPHONATE

Distribution equilibria of lead(II) in the extraction with di(2-ethylhexyl)phosphoric acid and 2-ethylhexyl 2-ethylhexylphosphonic acid in toluene from aqueous ammonium nitrate solutions were measured at 303 K to elucidate the concentration dependencies of the reactant species on the distribution ratio. It was found that lead(II) is extracted as the mononuclear complex, PbR₂2HR, with the former extrac-tant while it is extracted not only as the complex, PbR₂2HR, but also as the complex, Pb(NO₃)R;HR, accompanied by simultaneous transfer of nitrate anion with the latter ex-tractant. The extraction equilibrium constants of these complexes were evaluated as well as the stability constants of lead(II) -nitrato complexes, Pb(NO₃)⁺, Pb(NO₃)₂and Pb(NO₃)^? ₃.     

协合型增稠剂的流变性及其应用性能的研究

本文采用Brookfield RVT型旋转粘度计进行粘度测定,研究协合协增稠剂的流变性,将粘度数据进行计算机处理,回归出Casson方程,获得屈服值和无穷大剪切粘度,以描述增稠体系的遮盖力、稳定性、流平和流挂、沉降等性质,并对耐电解质性和后增稠进行了测试。本方法通过对粘度的测定,提供了一种对增稠剂的应用性能进行综合评价的途径。     

EXTRACTION OF TRIVALENT LANTHANIDES AND ACTINIDES BY A SYNERGISTIC MIXTURE OF THENOYLTRIFLUOROACETONE AND A LINEAR POLYETHER

Abstract

Mixtures of a linear polyether, l,13-bis[8-quinolyl]-l,4,7,10,13-pentaoxatridecane, K-5, and thenoyltrifluoroacetone, HTTA, have been shown to exhibit synergistic character in the extraction of trivalent lanthanides and actinides. The effect of the addition of K-5 to the organic phase on the extractions of Ce(III), Eu(III), Tm(III), Am(III), Cm(III), Bk(III), and Cf(III) by HTTA in chloroform from 0.5M NaNO₃ at 25°C has been measured. These results indicate the extraction is enhanced by the formation of M(TTA)₃K-5 adduct in the organic phase. The organic phase stability constants for the formation of these synergistic species have been calculated for all the metals studied. The magnitude of these organic phase stability constants for K-5 are similar to other common neutral donors. The order of stability does not follow the normal trend based on charge-to-radius ratio, but follows a pattern based on size, with Am(III) being the most stable.     

Characterization of the Interaction between Gallic Acid and Lysozyme by Molecular Dynamics Simulation and Optical Spectroscopy

The binding interaction between gallic acid (GA) and lysozyme (LYS) was investigated and compared by molecular dynamics (MD) simulation and spectral techniques. The results from spectroscopy indicate that GA binds to LYS to generate a static complex. The binding constants and thermodynamic parameters were calculated. MD simulation revealed that the main driving forces for GA binding to LYS are hydrogen bonding and hydrophobic interactions. The root-mean-square deviation verified that GA and LYS bind to form a stable complex, while the root-mean-square fluctuation results showed that the stability of the GA-LYS complex at 298 K was higher than that at 310 K. The calculated free binding energies from the molecular mechanics/Poisson-Boltzmann surface area method showed that van der Waals forces and electrostatic interactions are the predominant intermolecular forces. The MD simulation was consistent with the spectral experiments. This study provides a reference for future study of the pharmacological mechanism of GA.     

LIQUID-LIQUID EXTRACTION STUDIES OF METAL IONS WITH DITHIACROWN COMPOUNDS

The extraction properties of dibenzo-1, 10-dithia-[18]crown-6 compounds have been investigated. Especially thiophilic metals are effectively extracted. The extraction of Ag(I), Pd(II) and Au(III) is much greater than that of Hg(II) or Cu(I). Alkali and alkaline earth metals are not extracted. The experimental results show the coordination of metal ions with sulfur is decisive for the extraction. The variation of the subetituents at the macrocyclic ring from CH₃- t o CH₂Cl-groups influences the extraction power considerably. In contrast, the substitution on the benzo groups shows a less strong effect. The influence of diluents and counter anions on extraction are comparable with results in known crown ether systems. Synergistic extraction is observed for silver and mixtures of dithiacrown compounds and HDEHP, n-caprylic acid or TBP.     

Acetic Acid Extraction by Solvent Membrane

Abstract

Solvent extraction of acetic acid at low concentrations from aqueous solutions was studied. Decalin was found to be the optimal solvent and trioctyl phosphine oxide an effective carrier species. Phase equilibrium constants were measured and the results agree with the theoretical equation in the low carrier concentration range. The polymer supported solvent membranes carrying the same solvent and carrier, under various physical and chemical conditions, were prepared and the apparent diffusion coefficients of acetic acid through these membranes were measured and the results were discussed. The apparent diffusion coefficient of acetic acid in these tests was not interfered with by the existence of hydrochloric acid in the feed stream.     

Kinetics study on the reactive extraction of homophenylalanine enantiomers with BINAP-copper complex

This paper reports on the kinetics study of the reactive extraction of homophenylalanine (Hph) enantiomers with BINAP (2,2’-Bis(diphenylphosphino)-1,1’-binaphthalene)-copper complex (BINAP-Cu) as the chiral selector. The kinetic model was established based on the theory of interfacial chemical reactive extraction. Simultaneously, the effects of agitation speed, interface area, pH value of the aqueous phase, initial concentration of Hph enantiomers and initial concentration of BINAP-Cu on the specific rate of extraction were investigated. The forward rate constants of the reactions in reactive extraction process were found to be 6.16 × 10^?4 m^2.5mol^?0.5s^?1 for D-Hphe and 7.303 × 10^?4 m^2.5mol^?0.5s^?1 for L-Hphe.     

菁染料与溴化银相互作用性质的研究

本文用计时电位法及电位滴定研究了十六种不同染料与溴化银之间的相互作用,进一步证明了具有离域π-电子的菁染料才能与卤化银形成络合物的论点。从得到的平衡常数K表明,固体表面上的卤化银-染料与溶液中银离子-染料具有相同键性质,都是银离子与染料离域π-电子作用的结果。     

Use of the microchannel dimensions for studying assisted ion transfers at liquid-liquid supported microinterface

This paper confirms that, in the case of a more complex system like an assisted transfer of a metallic cation, the supported liquid-liquid microinterface behaves like a recessed or inlaid electrode depending on the transfer direction. This asymmetrical situation is a great advantage when studying the interfacial mechanism. We can thus determine in which phase the formation of the complex takes place. In this way, a well-known system, extraction of Zn(II) ions by 8-hydroxyquinoline, was studied. Three microchannels with various lengths but with an identical diameter were used to increase the asymmetrical situation. Voltammetric curves at various scan speeds give information on the diffusion pattern of complex transfer depending on the length of the microchannels. The complex is formed in the aqueous solution and so it is transferred into the organic solution. The stability constants of Zn(II)-HQ complex in water and in dichloroethane were evaluated. The transfer potential was also evaluated independently of the experimental apparatus. These results clearly show that this experimental device is a very well-adapted tool for studying systems, which present transfers of species across liquid-liquid interfaces.     

Complexes of Silver(I) Ions and Silver Phosphate Nanoparticles with Hyaluronic Acid and/or Chitosan as Promising Antimicrobial Agents for Vascular Grafts

Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes.     

Palladium Extraction from Nitric Acid Solutions by LIX 84 and LIX 860-I

ABSTRACT

The extraction of Pd(II) from weakly nitric acid solutions by LIX 84 (2-hydroxy-5-nonylacetophenone oxime) and LIX 860-I (5-dodecylsalicylaldoxime) dissolved in toluene has been studied and compared from the viewpoint of extraction equilibria. The effects of pH, nitrate ions and metal and extractant concentrations on the palladium distribution ratio have been quantified. The extraction rate of Pd(II) from this media is slow but the metal is quantitatively extracted by adding just the stoichiometric amount of the extractants. The experimental data have been treated graphically and numerically by means of the Letagrop-Distr program and can be explained by assuming the formation of the chelate PdL₂. Values of the extraction constants are also given.