二-(2-乙基己基)磷酸在不同稀释剂中对钼(VI)的萃取

考察了Mo(VI)在盐酸水相与-二(2-乙基己基)磷酸的不同稀释有机相间的分配平衡,观察到萃取平稀常数按正辛烷、四氯化碳、苯、氯信、1,2-二氯乙烷、甲苯、甲基异丁基酮的次序递减,萃合物的组成也按这一顺序呈现规律性变化.文中将这些结果与稀释剂性进行了关联,得到萃取平衡常数与稀释剂的极性参数E~T间良好的线性关系.此外,本文还提出了H~2MoO~4的酸、碱式解离常数分别为0.158和1.21×10^13.     

二-(2-乙基己基)磷酸在不同稀释剂中对钼(Ⅵ)的萃取

考察了Mo(VI)在盐酸水相与二-(2-乙基己基)磷酸的不同稀释剂有机相间的分配平衡,观察到萃取平衡常数按正辛烷、四氯化碳、苯、氯仿、1,2-二氯乙烷、甲苯、甲基异丁基酮的次序递减,萃合物的组成也按这一顺序呈现规律性变化.文中将这些结果与稀释剂极性进行了关联,得到萃取平衡常数与稀释剂的极性参数E_T间良好的线性关系.此外,本文还提出了H_2MoO_4的酸、碱式解离常数分别为0.158和1.21×10(-13).     

2-羟基-4-(1-甲基庚氧基)二苯甲酮肟萃取钯(II)的动力学和机理

本文报道2-羟基-4-(1-甲基庚氧基)二苯甲酮肟(N530)在盐酸介质中萃取钯(II)的平衡和动力学研究结果.用分配法测定了N530的基本常数.平衡研究表明,N530萃取钯反应的表现平衡常数K~ex为10~[16.88±0.04]氯仿作稀释剂)和10~[18.00±0.01](正十二烷作稀释剂).动力学研究表明,水相中的取代反应为决速步骤,K,1为2.42x10~2L.mol^-1.s^-1.测得萃取反应活化能为30.0±3.2(氯仿)和28.9±1.9KJ.mol^-1(正十二烷),与稀释剂无明显关系.界面特性研究表明,界面饱和时有机相体相浓度为10^-2mol.L^-1,小于测定速率方程时的浓度,这些都进一步证实了水相反应机理而排斥了界面反应机理.     

二-(2-乙基己基)磷酸在不同稀释剂中对钙、钴(Ⅱ)的萃取

本文测定了25±1℃时二-(2-乙基己基)磷酸在不同稀释剂中从硫酸盐水溶液里对钙、钴(Ⅱ)的萃取,计算得到了萃取络合物中结合的自由萃取剂分子数和萃取平衡的表观常数,并讨论了溶剂对萃取的影响。     

2-羟基-4-(1-甲基庚氧基)二苯甲酮肟萃取钯(Ⅱ)的动力学和机理

本文报道2-羟基-4-(1-甲基庚氧基)二苯甲酮肟(N530)在盐酸介质中萃取钯(II)的平衡和动力学研究结果.用分配法测定了N530的基本常数.平衡研究表明,N530萃取钯反应的表观平衡常数K_(ex)为10~(16.88±0.04)(氯仿作稀释剂)和10~(18.00±0.01)(正十二烷作稀释剂).动力学研究表明,水相中的取代反应为决速步骤,k_1为2.42×10~2L·mol~(-1)·s~(-1).测得萃取反应活化能为30.0±3.2(氯仿)和28.9±1.9kJ·mol~(-1)(正十二烷),与稀释剂无明显关系.界面特性研究表明,界面饱和时有机相体相浓度为10~(-2)mol·L~(-1),小于测定速率方程时的浓度,这些都进一步证实了水相反应机理而排斥了界面反应机理.     

在不同稀释剂中二(2－乙基己基)磷酸萃取Ni(Ⅱ)的热力学

研究了在不同稀释剂如苯、甲苯、正己烷、环己烷、四氯化碳、氯仿中萃取剂浓度、水相酸度以及温度对二(2-乙基己基)磷酸萃取Ni(Ⅱ)的平衡的影响,借助萃合物红外光谱,确定了萃合物组成和萃取反应机理。讨论了稀释剂的影响,利用多参数方程将萃取平衡常数以及分配比与稀释剂的物理常数和经验参数进行了定量关联。     

α-烃基取代吡啶对金(Ⅲ)的萃取研究(Ⅰ)——电离常数的测定和金的萃取行为

用紫外吸收光谱测定了α-烃基取代吡啶质子化合物的电离常数。比较了各种α-烃基取代吡啶分子的碱性和取代基位阻对金(Ⅲ)萃取的影响。讨论了金(Ⅲ)的萃取机理。还对水相中盐酸的浓度、萃取剂的浓度、稀释剂、温度和阴、阳离子对萃取选择性的影响进行了研究。     

稀释剂对P_(538)萃取Fe(Ⅲ)的影响

前文探讨了P_(538)(ROP(O)(OH)_2,R=C_(12)—C_(18))在煤油中萃取Fe(Ⅲ)的机理,本文在此基础上研究了稀释剂对萃取Fe(Ⅲ)的影响,并按正规溶液理论,讨论了不同稀释剂的溶解度参数与分配比之间的关系。     

~1H NMR法测量N-甲基-2-吡咯烷酮、环丁砜N,N-二甲基甲酰胺、N,N-二甲基乙酰胺、γ-丁内酯与某些芳烃的分子配合常数

从石油馏分中提取芳烃、烯烃、二烯烃和炔烃等组分具有重大的经济价值.通常提取这些组分的方法为液-液萃取或气-液萃取.效果较佳的萃取剂有N*甲基-2-吡咯烷酮(NMP)、环丁砜、N,N-二甲基甲酰胺(DMF)、N,N-二甲基乙酰胺(DMA)和γ-丁内酯(γ-BL)等.为了揭示这些萃取剂萃取芳烃的机制,作者曾测量NMP、DMF、DMA、环丁砜与某些芳烃构成二元系的过量体积,用紫外-可见分光光度法测量NMP与某些芳烃的分子配合常数以及用气液色谱法测量环丁砜与某些芳烃的分子配合常数.本文报道以四氯化碳作为惰性稀释剂,用~1H NMR方法测量NMP等萃取剂与C_6～C_9芳烃的分子配合常数.     

新型萃取剂用于Am(Ⅲ)和Eu(Ⅲ)的分离

本文研究了一种新型萃取剂用于Am(Ⅲ)/Eu(Ⅲ)的分离,并做了以下条件的研究:(1)不同酸度的影响(0.1-0.3mol/LHNO3);(2)不同稀释剂的影响,采用I 241Am和152-154Eu作示踪剂。结果表明在3mol/LH-NO3体系中241Am能被萃取出来,而152-154Eu几乎不能被萃取。在0.1-0.3mol/LHNO3条件下,用硝基苯胺稀释剂,萃取分离系数达到70。     

Thermoelastic properties of networks in swelling equilibrium: Poly(vinyl alcohol)

The energy component of the stress has been determined for poly(vinyl alcohol) networks in swelling equilibrium with a series of water–ethylene glycol compositions. The data are analyzed by using the equations describing the thermoelasticity of networks in swelling equilibrium. The ratio f_e/f of the energy component to the total force, as calculated from these equations, varies systematically with diluent composition but is independent of elongation in a given diluent. For a network crosslinked by terephthalaldehyde, f_e/f varied from ?0.33 to ?0.42 as the diluent composition was changed from pure water to 20% ethylene glycol. Similar effects were found in a network crosslinked by formaldehyde. It is not yet certain whether this effect represents a real solvent dependence of f_e/f or a failure of the equation of state to account for the effect of composition changes on the force.     

Crystallization of poly(vinylidene fluoride): Equilibrium melting point and heat of fusion of the α-polymorph

Samples of poly(vinylidene fluoride) were crystallized either (a) isothermally at a series of temperatures, or (b) in the presence of varying amounts of diluent (dimethylphthalate or dimethylacetamide). The α-polymorph was the only crystalline form present in these samples. Melting points of the first series (a) were determined by DSC and of the second (b) by dilatometry. The same equilibrium melting point for the α-polymorph (178°C) was obtained from analysis of the two sets of data. A value of 1425 cal mole^?1 (5.96 kJ mole^?1) for the heat of fusion of this polymorph was obtained from analysis of the polymer–diluent melting data. The heat of fusion and the entropy of fusion calculated therefrom correlated well with corresponding values for other fluoroethylene polymers. Thus, the equilibrium melting point and the heat of fusion could be predicted for a fluoropolymer for which data have not yet been reported–poly(trifluoroethylene). The melting point predicted, 222°C, agreed remarkably well with that determined here for an experimental sample, thereby lending support to the empirical correlations. The heat of fusion of poly(trifluoroethylene) is, therefore, expected to be approximately 1300 cal mole^?1.     

1-(2-pyridylazo)-2-naphthol (PAN) as extractant in solid-liquid extraction of some trivalent rare earth elements

In the present paper, solid-liquid extraction behaviour of RE(III) (RE La, Ce, Pr, Nd, Sm, Gd, Dy and Yb) by the use of 1-(2-pyridylazo)-2-naphthol (PAN, HL) as an extractant in paraffin (m.p. 48 approximately 50 degrees) has been investigated at 80 +/- 0.07 degrees. The effect of equilibrium time, pH of aqueous phase, concentration of extractant in paraffin and solid diluent as well as buffer solution used on the extraction efficiency of RE(III) have been discussed. The extraction reaction is RE(3+) + 2HL(o) + Cl(-) <==> REL(2)Cl(o) + 2H(+).     

Solvent extraction of copper(II) from sulfate medium with N -(2-hydroxybenzylidene)aniline

Solvent extraction of copper(II) from sulfate medium with N-(2-hydroxybenzylidene)aniline is studied with the following parameters: pH, concentration of the extractant, nature of diluent, and temperature. The extraction of copper(II) proceeds by a cation exchange mechanism and the extracted species are CuL₂ in cyclohexane and toluene and CuL₂ with some CuL₂HL in chloroform. The equilibrium constants have been calculated as well as thermodynamic parameters ΔH°, ΔS°, and ΔG°. The temperature effect on the solvent extraction of copper(II) with N-(2-hydroxybenzylidene)aniline in cyclohexane is discussed.     

Extraction of uranium(VI) and thorium(IV) ions from nitric acid solutions by N,N,N′,N′-tetrabutyladipicamide

A new symmetrical diamide, the straight-chain alakyl substituted neutral tetrabutyladipicamide (TBAA) has been synthesized, characterized and used for the extraction of U(V) and Th(IV) from nitric acid solutions in a diluent composed of 50% 1,2,4-trimethylbenzene (TMB) and 50% kerosene (OK). Extraction distribution coefficients of U(VI) and Th(IV) as a function of aqueous nitric acid concentration, extractant concentration and temperature have been studied. Back-extraction of U(VI) and Th(IV) from organic phases by dilute nitric acid has been undertaken. From the data, the compositions of extracted species, equilibrium constants and enthalpies of extraction reactions have also been calculated.     

The effect of diluents on extraction of copper(II) with di(2-ethylhexyl)phosphoric acid

The liquid–liquid extraction of copper(II) from sulfate medium with di(2-ethylhexyl)phosphoric acid (D2EHPA, HL) at 25°C is studied with the following parameters: pH, concentration of the extractant, and the nature of diluent. The effect of the diluent using polar and nonpolar solvents in the extraction of copper(II) is discussed. The extracted copper(II) species were CuL₂ in 1-octanol and methyl isobutyl ketone and CuL₂ · 2HL in toluene, carbon tetrachloride, and cyclohexane. The extraction constants are evaluated for different diluents.     

Extraction equilibrium between primary amine primene 81R and iron(III) sulphate

The extraction equilibrium between aqueous iron (III) sulphate solutions and amine Primene 81R was studied. The results show that the free amine extracts iron(III) from these solutions. The extracted complex has been isolated and can be represented by the stoichiometric formula 4RNH₂·Fe₂(SO₄)₃. The extraction reaction is almost independent of temperature and change in the diluent of the organic phase. On the basis spectral studies a structure for the extracted complex is suggested.     

Dibutyl N,N-dibutylcarbamoylmethylphosphonate extraction of Eu(III) from perchlorate and nitrate solutions

Dibutyl N,N,-dibutylcarbamoylmethylphosphonate (DBDBCMP) has been used in the extraction study of Eu(III) from low acidic solutions. The different parameters affecting the distribution ratio have been studied. The reaction is considered as a chelate interaction and the extracted species are Eu(OH)₂ DBDBCMP·2HDBDBCMP and Eu(NO₃)₂ DBDBCMP. HDBDBCMP from perchlorate and nitrate, respectively. The equilibrium constants corresponding to the different species formed are calculated and discussed. The effect of changing diluent on extraction capacity of the phosphonate is also studied and discussed.     

Suspension polymerization of poly(ethylene glycol) methacrylate: a route for swellable spherical gel beads with controlled hydrophilicity and functionality

 Spherical and swellable gel beads were obtained by the suspension polymerization of poly(ethylene glycol) methacrylate macromonomer (PEG-MA). The average size and size distribution properties, the equilibrium swelling behaviour and the protein adsorption characteristics of PEG-MA-based gel beads were determined. In the suspension polymerization system, the organic phase including monomer, cross-linker and diluent solution was dispersed in an aqueous medium by using poly(vinylpyrrolidone) as the stabilizer. The diluent solution was prepared by mixing cyclohexanol and octanol at different volume ratios. The suspension polymerization experiments were designed in two separate parts. In the first part, ethylene glycol dimethacrylate was selected as the cross-linker and swellable PEG-MA-based gel beads were obtained by changing the cross-linker concentration, the monomer/diluent ratio and the stirring rate. In the second part, a more hydrophobic structure, divinylbenzene (DVB) was tried as a cross-linker. In this part, PEG-MA-DVB copolymer beads were obtained by changing the DVB/PEG-MA feed ratio. Then, the hydrophicility of the resulting gel beads could be controlled by changing the feed ratio of hydrophilic macromonomer to hydrophobic cross-linker. This property was also used to control the extent of nonspecific protein adsorption onto the surface of the gel beads. The non specific albumin adsorption onto the gel beads decreased with increasing PEG-MA content. No significant nonspecific adsorption at the isoelectric point of albumin was detected onto the gel beads produced with the higher PEG-MA/DVB feed ratios. For specific albumin adsorption, a triazinyl dye (i.e., cibacron blue, CB F3G-A) was covalently attached onto the surface of the copolymer beads via terminal hydroxyl groups of PEG-MA. The results of albumin adsorption experiments with the CB F3G-A carrying beads indicated that an appreciable specific albumin adsorption capacity could be obtained with the gel beads produced with a PEG-MA/DVB feed ratio of 1.5/4.0. Received: 16 August 1999/Revised: 27 December 1999     

Olefin cross-metathesis of a vinyl-terminated self-assembled monolayer (SAM) on Au(111): electrochemical study using a ferrocenyl redox center

Self-assembled thiol monolayers bound to single-crystal Au(111) surfaces containing a terminal olefin have been prepared and used to monitor electrochemically the cross-metathesis (CM) between the surface and an olefin-terminated ferrocenyl (Fc) derivative from solution over time. Mixed SAM surfaces were prepared by first adsorbing a diluent for 2 days followed by the olefinic alkanethiol for known adsorption time intervals; three diluents of varying length were used. The oxidation peak areas from the voltammetry show the CM reaction yields a maximum amount of product at 100-150 min. Beyond this time, thiol desorption is apparent and the Fc oxidation peaks diminished. A kinetic simulation of the interfacial reactions involving CM and desorption reactions are described and aided in the interpretation of the voltammetric responses. The length of the diluent and the coverage of surface olefins were important factors in limiting undesirable self-CM reactions on the surface, and a model of the relationship between the diluent and surface concentration of olefin is described. This study shows that attention to monolayer formation and reaction conditions are important parameters when maximizing CM yields on surfaces.