ISOTOPIC EXCHANGE OF OXYGEN 18O BETWEEN THE GASEOUS PHASE AND OXIDE CATALYSTS

This review is concerned with the isotopic exchange (IE) of oxygen^l8O between gaseous oxygen and solids.     

聚铝溶液pH值及盐基度的相关性研究

为聚铝溶液进行了ＰＨ值和盐基度的分析和估算,给出了聚铝溶液的极限ＰＨ值和极限盐基度与总溶解铝浓度的关系曲线,最终计算结果表明：在平衡条件下,聚铝溶液的ＰＨ值和盐基度具有相关性,即当基中一个参数发生变化时。另一个参数必然要发生相应的改变。     

聚铁溶液pH值及盐基度的相关性研究

对聚铁溶液进行ｐＨ值和盐基度的分析和估算,给出了聚铁溶液的极限ｐＨ值和极限盐基度与总溶液铁浓度的关系曲线,最终计算结果表明,在平衡条件下,聚铁溶液的ｐＨ值和盐基度具有相关性,即当基中一个参数发生变化时,另一个参数必然要发生相应的改变。随着总溶解铁浓度的不断升高,极限ｐＨ值单调下降,而极限盐基度却单调递增。对于铁含量为１６０ｇ／Ｌ的标准聚铁溶液,其最大ｐＨ值为１．３１４,最高盐基度为１９．９９％。     

NaY分子筛与氯化稀土溶液加压连续交换的研究

在螺旋管反应装置上研究了混合氯化稀土与NaY分子筛在水溶液中的加压连续离子交换反应动力学。测定了不同温度下RE~(3+)-Na~+离子交换反应动力学数据;并考察了投料比对动力学的影响;讨论了离子交换反应的控制步骤;得出了有利于加压连续交换的条件以及有关动力学参数。     

CORRELATIONS FOR ESTIMATING THE DIFFUSIVITIES OF NITROUS OXIDE IN AQUEOUS SOLUTIONS OF DIETHANOLAMINE AND N-METHYLDIETHANOLAMINE AND THE SOLUTION DENSITIES AND VISCOSITIES

Experimentally measured diffusion coefficients of nitrous oxide in water, aqueous solutions of diethanolamine, aqueous solutions of N-methyldiethanolamine, and aqueous blends of diethanolamine and N-methyldiethanolamine have been used to arrive at a modified Stokes-Einstein correlation by using nonlinear least-squares filling. The average deviation of this correlation from the experimentally measured diffusion coefficients is about 13%. Comparisons are also made to the estimated diffusivities of nitrous oxide in the amine solutions which are obtained from the Wilke-Chang and Hayduk-Minhas correlations. The average deviations of the Wilke-Chang and Hayduk-Minhas correlations from the measured values are about 13% and 19%, respectively. Correlations were also presented for estimating the solution densities and viscosities. Predicted values for the solution densities and viscosities from these correlations deviate from experimentally measured values on average by 1.2% and 4.8% respectively.     

胶原／明胶的结构（构象）与性能研究V．铜离子与明胶中不同构象组分络合形态的研究

利用ＣＭ－５２离子交换层析和无火焰原子吸收光谱法对明胶中铜离子与不同构象组分络合形态进行了研究。其研究结果表明：明胶中的铜离子是与明胶大分子中的不同构象（α、β和γ）组分中的游离基因以络合的形式稳定地存在着，铜离子与不同构象的络合能力大小可以排列成以下的顺序：（γ＞β＞α）。金属铜与不同构象络合的能力是如此之强，以致明胶中微量的铜离子可以认为是明胶大分子结构中的一部分。     

A KINETIC APPROACH TO EVALUATE THE ENERGY AND ENTROPY OF ACTIVATION FOR THE EXCHANGE OF ALKALINE EARTH METAL IONS ON TIN(IV) TUNGSTATE CATION EXCHANGER

Abstract

A new approach based on the Nernst-Planck equations has been applied to study the reaction kinetics on the surface of tin(IV) tungstate for the Mg(II)-H(I), Ca(II)-H(I), Sr(II)-H(I) and Ba(IT)-H(I) exchanges under the conditions favouring a particle diffusion phenomenon. On the basis of these studies the various physical parameters such as the effective diffusion coefficients, activation energies and entropies of activation have been evaluated which give some informations regarding the mechanism of ion-exchange on the surface of inorganic materials.     

KINETICS AND MECHANISM OF ISOTOPIC EXCHANGE FOR Co2+/Co Co2+ IN TIN(IV) ANTIMONATE

ABSTRACT

The rate of the isotopic exchange of cobalt ion between tin(IV) antimonate ion exchanger in the Co Co²⁺ form and aqueous solutions vas determined radiometrically. Self-diffusion coefficients for cobalt ion were measured as a function of the variable capacity for that ion in solutions of varying acidity. The effect of a heat treatment on the rate of the isotopic exchange reaction in tin(IV) antimonate vas also studied. The rate vas controlled by the particle diffusion of cobalt ion and increased by heating temperature and decreased with increase of ion exchange capacity. Values for the diffusion coefficentst activation energy and entropy of activation have been evaluated which give some information regarding the mechanism of ion exchange on the surface of inorganic materials.     

SYNTHETIC INORGANIC ION-EXCHANGE MATERIALS XXXIX. SYNTHESIS OF TITANIUM(IV) ANTIMONATES AND THEIR ION EXCHANGE PROPERTIES FOR ALKALI AND ALKALINE EARTH METAL IONS

ABSTRACT

Titanium antimonate (TiSbA) cation exchanger, prepared under different molar ratios of titanium and antimony, has been characterized by X-ray diffraction, thermal analysis, infrared spectra, and pH-titration. The pH-titration curves showed apparently monobasic acid type. The uptakes of alkali metal ions increased with increasing pH of the solution and with decreasing the molar ratio (Ti/Sb) in the exchanger. An unusual selectivity sequence of the order Na < K < Rb < Cs was found for microamounts of alkali metal ions on TiSbA, while the regular selectivity sequence Mg < Sr < Ba was found for alkaline earth metal ions in nitric acid media. The maximum separation factors, ∝^Li _Na(=55) and ∝(=186) were found on the TiSbA with Ti/Sb molar ratio of 1.56, respectively. The effective separations of Li from Na and K, Mg from Ca and Sr have been achieved by using a relatively small column (2 cm × 0.5 cm i.d. ) containing TiSbA of Ti/Sb ratio 1.56.     

EXTRACTION STUDIES ON THE SYSTEM BETWEEN BIS(2-ETHYLHEXYL) PHOSPHORIC ACID AND CHROMIUM(III) IN SEVERAL AQUEOUS SOLUTIONS

The extraction of chromium(III) by carboxylic acids and acidic organophosphorus compounds has been investigated. In general, chromium(III) was not extracted by carboxylic acids but the organophosphorus compound, di-2-ethylhexyl phosphoric acid, was found to be particularly adequate for the extraction. The partition of chromium(III) in nitrate medium and solutions of di-2-ethylhexyl phosphoric acid in Shellsol-T was studied using a tracer of 51cr. Distribution measurements of the metal ion in a wide range of pH and organophosphoric acid concentrations have been performed. The experimental data treated by a graphical method have been explained assuming the presence in the organic phase of the species Cr(DEHP)₃(H₂O)²(HDEHP). Equilibrium constants for the different extraction reactions are given. The extraction of the monomeric species was found to be independent of Ac^?or SO⁼ ₄ions presence.     

THE SEPARATION OF Au(III) AND Pd(II) IN HYDROCHLORIC ACID SOLUTIONS BY STRONG ANION TYPE II EXCHANGE RESINS: THE EFFECT OF COUNTER ION CONCENTRATION AND TEMPERATURE

ABSTRACT

The separation of gold and palladium ions in hydrochloric acid solutions by strong anion Type II exchange resins is studied in batch and column operations. Increases in the hydrochloric acid concentration and the temperature of the adsorption process have the effect of decreasing the adsorption capacity and the separation factor of both metals. A faster kinetics of the adsorption process of both ions results from temperature increase and this effect is higher for gold ions as a result of greater changes in its diffusivity. Although the adsorption capacity of palladium ions is lower at equilibrium conditions, the adsorption isotherms obtained suggest that they are more strongly retained by the polymers.

The high capacities of these resins for both metals permits their use in the preconcentration of gold and palladium but their application in quantitative separation is restricted by the co-elution of up to% of the interfering ion during the desorption process. The best method for ion desorption is sequential elution with% ammonia for palladium recovery followed by 0·5M thiourea in HCI 1M for the recovery of gold.     

CALORIMETRIC STUDIES OF THE SYNERGISTIC EFFECT. THE REACTION OF UO2 2+, Th 4+ AND Nd 3+ TTA COMPLEXES WITH TBP AND TOPO IN BENZENE

Titration calorimetry was used to investigate the thermodynamics (ΔG, ΔH, ΔS) of the addition reactions between M(TTA)_n(H₂O)_m (where M = UO₂ ²⁺, Th⁴⁺, Nd³⁺) and TBP or TOPO in dry and in water saturated benzene solvent. The adduct species formed were UO₂((TTA)₂ S, Th(TTA)₄ S, and Nd(TTA)₃ S_n (n = 1,2).The thermodynamic values complemented by water analysis data, allow evaluation of the relative importance of enthalpic and entropic contributions of ΔG, of the role played by water and of the changes in coordination number which occur during the reactions with the adduct ligands.     

废醋纤(WCA)再生烟滤嘴纤维研究第Ⅱ报、WCA丙酮溶液的流变性和可纺性

用旋转粘度计研完了WCA丙酮溶液的流变性质,考察了溶液对切变速率、增塑剂含量、浓度、温度的依赖关系,并对可纺性进行了研究。研究结果表明,WCA丙酮溶液的粘弹性低于CA丙酮溶液,WCA丙酮溶液的可纺性良好。