Unusual Selectivities of Stannic Arsenate Layers in DMSO-HCI Systems: Separation of Zirconium from Numerous Metal Ions

Abstract

The adsorption behavior of 52 metal ions has been studied in DMSO-HCI systems using stannic arsenate layers. A remarkable feature of this study is a dramatic decrease in adsorption of many ions when compared to the corresponding water-HCI systems. This specific DMSO effect has been explained and used for important binary and ternary separations. In DMSO-5 M HCI (1:1), Zr^{4 +} and Mo^{6 +} have been separated from each other and from a mixture of Th^{4 +}, Ca^{2 +}, Y^{3 +}, Nb^{5 +}, Ta^{5 +}, In^{3 +}, Ti^{4 +}, and the rare earths.     

Sorption of Uranium and other Metal Ions on Amine-Functionalized Silica Materials

Sorption of U(VI) and other metal ions on amine-functionalized silica was studied, including aminopropylsilica (APS), 3-(ethylenediamino)propyl silica (ENPS), and 3-[2-(2-aminoethylamino)ethylamino]propyl silica (DIENPS). DIENPS showed the strongest and fastest sorption for U(VI) that can be described by Langmuir isotherm, suggesting U(VI) was sorbed at well-defined and energetically identical sites independent from each other. The sorption efficiency of DIENPS follows the order: U(VI) > Fe(III) > Cu(II) > Pb(II) > Ni(II) > Mg(II) > Sr(II). Results demonstrate that the amine-functionalized silica materials could be used as efficient sorbents to remove uranium and hazardous metal ions in environmental remediation.     

Metastable Liquid Immiscibility in Alkali Metal Oxide–Silica Systems

A search was made for evidence of metastable phase separation in binary alkali metal oxide-silica glasses which had been subjected to the usual glassmaking procedures of melting, relatively fast cooling, and annealing. Electron microscopy and electrical properties measurements were the principal tools of investigation. Evidence for phase separation in Li₂O and Na₂O silica systems is given together with critical temperature estimates. Although K₂O-SiO₂ glasses showed some slight evidences of structural segregation it is concluded that binary K₂O, Rb₂O, and Cs₂O silica glasses generally show simple solution behavior and allow reasonable correlations of properties with cation size, type, and separation.     

Removal of Toxic/Heavy Metal Ions Using Ion-Imprinted Aminofunctionalized Silica Gel

Abstract

The investigation reports the preparation and evaluation of Cr(III) and Fe(III)-imprinted amino-functionalized silica gel adsorbents (APTS-Cr(III)-Si and APTS-Fe(III)-Si) for selective solid-phase extraction of Cr(III) and Fe(III), respectively, from aqueous solutions. The adsorbent materials were prepared by a surface imprinting technique using 3-aminopropyltrimethoxysilane as the surface modifying ligand. The effects of solution pH, sorption time, temperature, and initial metal ion concentration upon adsorption characteristics were investigated. The adsorption isotherms for Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) were evaluated and the thermodynamics of the adsorption processes were correlated. By optimizing the parameters, the synthesized materials could be used successfully for selective removal of trivalent cations from a mixture of cations in dilute aqueous solution.     

Thin-Layer Chromatography of 49 Metal Ions on Stannic Antimonate in Aqueous and Mixed Solvent Systems Containing Dimethylsulfoxide: Quantitative Separation of Uranium from Numerous Metal Ions

Abstract

Thin-layer chromatography of 40 metal ions in 31 aqueous and mixed solvent systems has been performed on stannic antimonate ion-exchange material. Dimethylsulfoxide has been utilized to resolve such binary mixtures as La³⁺ and Ce³⁺ from Pr³⁺, Nd³⁺, and Sm³⁺; VO²⁺ from Ti⁴⁺, Nb⁵⁺, and Ta⁵⁺; Ga³⁺ from In³⁺, Tl⁺, and Y³⁺; Fe³⁺ from VO²⁺; and Mg²⁺ from Al³⁺.

Quantitative separation of 200 to 800 μg U from its binary mixtures and from the synthetic mixtures containing Mg²⁺, Bi³⁺, Fe³⁺, Th⁴⁺, Ce⁴⁺, Cr³⁺, Zr⁴⁺, Hf⁴⁺, Ti⁴⁺, Mn²⁺, Cu²⁺, Ce³⁺, In³⁺, Y³⁺, Ca²⁺, Co²⁺, Tl⁺, Nb⁵⁺, and Ag⁺ has been obtained.     

金属螯合双水相亲和分配技术分离纳豆激酶的研究

利用金属螯合亲和双水相分配技术对纳豆激酶的分离纯化进行了研究。考察了双水相系统、聚合物的分子量和浓度、亲和配基加入量、pH值、相比以及生物质加入量等因素对亲和分配的影响。结果表明,双聚合物系统比聚合物／无机盐系统更有利于纳豆激酶亲和分配;pH值和亲和配基加入量是影响分配的关键因素。优化的分配条件为：2．6％聚乙二醇,20．2％羟丙基淀粉,5％亲和配基PEG-IDA—Cu(Ⅱ),相比12,pH8．2,发酵液加入量15％。分配系统放大到100g,仍保持一致的酶活收率(90％)和纯化因子(2.0)。设计了两次分配分离流程,纯化因子达到3．52,总收率为81％。     

Diffusion of Alkali Ions in Vitreous Silica

The diffusion of Cs⁺, Rb⁺, and K⁺ ions was measured in three grades of vitreous SiO₂ by the radiotracer-sectioning technique or Rutherford, backscattering spectroscopy. The values of the diffusion coefficient, D , at 1000°C decrease strongly with increasing ionic radius, changing by about two and one-half orders of magnitude per row of the periodic table. The difference between D_Cs and D_Rb is largely in the preexponential factor D_o in the Arrhenius expression rather than in the activation enthalpy Q . The values of D are much smaller than the tracer D values for the alkali metal ion in homogeneous Rb or Cs silicate glasses. Residual metallic impurities in the SiO₂ decrease both Q and D_o for the diffusion of Rb. The results are analyzed in terms of the interstitial structure of vitreous SiO₂.     

Chemical States of Implanted Aluminum Ions in Silica and Silicon Ions in Alumina

Aluminum and silicon ions have been implanted in silica glass and α-alumina single crystal, respectively, to doses ranging from 1 × 10¹⁵ to 1 × 10¹⁷ ions·cm^-2. The chemical states of these implanted ions have been studied by X-ray fluorescence spectroscopy. It is found that the implanted aluminum atoms are coordinated only by oxygen atoms, irrespective of implantation dose. On the other hand, the implanted silicon atoms are coordinated only by oxygen atoms at low doses and by both oxygen and silicon atoms at high doses. Although the chemical state of the aluminum atoms is unchanged by heat treatment, that of the silicon atoms is changed toward a less positively charged state. It is inferred that the chemical states of the implanted atoms are controlled by the transport process, although these tend to obey the thermodynamic stability.     

Synthesis of Amine-Functionalized MCM-41 and MCM-48 for Removal of Heavy Metal Ions from Aqueous Solutions

In this research amino functional mesoporous MCM-41 and MCM-48 materials were prepared in an attempt to develop efficient adsorbents for removal of heavy metals from aqueous solutions. The adsorbents were characterized by XRD, FTIR, and TG-DTG techniques. The synthesized adsorbents were used for the removal of Cu(II), Co(II), Cd(II), and Pb(II) from aqueous solutions for the first time, and the influence of some effective parameters including concentration, initial pH, contact time, and temperature on the sorption process was studied and optimized. Significant adsorption capacities were obtained at low concentrations. The kinetic studies showed that the adsorption process was fast and more than 90% of equilibrium capacity was achieved within 60 min. Experimental kinetic data was well fitted with the pseudo-second-order kinetic model. Thermodynamic parameters computed from the experimental data showed that the adsorption was endothermic and spontaneous.     

金属离子对厌氧消化的影响

金属离子对微生物的生长具有重要作用,是生物厌氧消化反应器稳定运行的重要影响因素。从轻金属离子和重金属离子两个方面对厌氧消化的影响进行了总结。     

腐植酸树脂/二氧化硅复合材料制备及其对重金属离子的吸附性能

以腐植酸和水玻璃为原料,采用酸化共沉淀方法制备了腐植酸树脂/SiO2复合材料. 在腐植酸树脂中引入SiO2无机网络后,比表面积有较大提高,在水溶液中的稳定性明显改善. 通过差热分析、傅立叶红外光谱、扫描电镜、比表面积测定等方法对样品进行了表征,研究了复合材料对Pb2+, Cd2+, Ni2+, Cu2+四种典型重金属离子的吸附性能,同时探讨了腐植酸组分对重金属离子的吸附机理. 结果表明,复合材料中的腐植酸组分对重金属离子的主要吸附形式应为离子交换吸附和络合(或螯合)吸附,复合材料对4种重金属离子有良好的吸附能力,对Pb2+, Cd2+, Ni2+, Cu2+的饱和吸附量分别为262.5, 43.55, 23.58, 45.54 mg/g,与同类吸附材料相比处于领先水平,对4种重金属离子的等温吸附符合Langmuir模型.     

Dissolved-Air Flotation of Metal Ions

Abstract

Metal ions (copper, nickel, zinc, and ferric ions) were separated from dilute aqueous solutions by dissolved-air flotation. The ions were either precipitated as sulfides or floated (as ions) by xanthates. Copper and nickel were selectively separated; promising results were obtained with single, binary, and ternary mixtures. The effect of several parameters (solution pH, addition of chemical reagents at varying concentrations, and the presence of other ions) on the removal of ions was studied. The collectorless flotation of copper ions was also investigated.     

硅溶胶中钠离子含量的准确测定

采用火焰光度计法测定普通碱性钠型硅溶胶中钠离子含量,研究了前处理方法对测定结果的影响,并用已知钠离子浓度的硅溶胶对该方法进行验证.结果表明,较佳前处理方法是si0:、氢氟酸和消解液按1:6:0.5的量之比混合,常温反应15 min;再稀释200～600倍,然后采用火焰光度计进行测定;验证实验结果表明,该法准确度和精密度...     

Affinity Partitioning of Metal Ions in Aqueous Polyethylene Glycol/Salt Two-Phase Systems with PEG-Modified Chelators

Abstract

The systematic partitioning of metal ions in the presence of polyethylene glycol (PEG) chelate derivatives in PEG/salt two-phase systems is described. Results show that the partitioning is enhanced significantly, and this effect is apparently based on the characteristics of binding of the chelate and the nature of the metal ion in addition to the effect of the attached PEG molecule. Previous work with PEG-iminodiacetic acid has been extended with the chelating derivatives PEG-TED [tris(carboxymethyl)ethylene diamine], PEG-TREN-Cm [carboxy-methylated-tris(2-aminoethyl)amine], and PEG-ASP (aspartic acid). Their effectiveness to selectively partition the metal ions is demonstrated and discussed. The partition experiments were performed using two-phase systems of PEG (8000 MW), sodium sulfate, the PEG-chelating derivatives, and different concentrations of copper, nickel, and cobalt as model metal ions. Partition coefficients (ratio of top to bottom metal concentrations) greater than 1 were obtained for the metal ions with all the chelating derivatives tested. Selective enhancement of partitioning was observed in all cases. Based on the experimental results and theoretical principles, the method shows potential as an alternative mode to remove efficiently and selectively metal ions from solutions using aqueous two-phase systems and PEG-chelate derivatives.     

Biosorptive Flotation in Metal Ions Recovery

Abstract

Heavy metals can be removed from dilute aqueous solutions in many ways. Among the innovative ones may be classified a process consisting of biosorption followed by flotation. A metal cation, cadmium, was examined; the metal was abstracted by microorganisms belonging to the Actinomycetes, i.e., Streptomyces clavuligerus and Streptomyces griseus, which have a filamentous morphology, and hence present a flocculent character. Dissolved-air flotation was the technique applied on a laboratory scale without the addition of any flotation surfactant. The parameters investigated in the batch mode were contact time, recycle ratio, solution pH, Cd concentration, biomass addition, and use of a frother (ethanol). Promising results were obtained; in certain cases an almost quantitative cadmium abstraction, followed by higher than 90% biomass recovery, was found.     

磷化液中金属离子的分析

0 引言 磷化作为金属涂装前处理工艺,已经得到广泛的应用.磷化工艺以前主要以锌系、钙系、锰系或锌-钙、锌-锰系二元磷化体系为主.随着涂装对表面处理质量要求的提高,三元磷化开始在阴极电泳中广泛应用.它能显著提高涂层的附着力,改善磷化膜质量,增强涂层的耐蚀性能.     

羧甲基壳聚糖对金属离子吸附的研究进展

羧甲基壳聚糖及其改性产品的吸附性能主要体现在对各种金属离子的的吸附上.为了有选择性地吸附某些金属离子,人们通过修饰、交联、接技等方法对羧甲基壳聚糖进行了各种改性研究.文章综述了1992年以来羧甲基壳聚糖及其衍生物在金属离子吸附方面的研究进展.展望了吸附剂存重金属离子废水处理过程中的巨大优势和良好的发展前景.     

杯芳烃衍生物与碱金属离子、碱土金属离子配合的研究进展

杯芳烃衍生物作为"第三代超分子",对金属离子有着优异的结合力和选择性,已广泛用于金属离子的萃取、离子色谱、催化、跨膜运输、离子通道以及自组装分子层等领域。综述了近年来杯芳烃及其衍生物与金属离子,主要是碱金属、碱土金属阳离子配合的最新进展。