Elution Behavior of Cesium from Ferrierite Column by Using Inorganic Salt and Acid Solutions

The distribution coefficient (K_d) of Cs on ferrierite decreased with increasing concentration of the coexisting inorganic cations in the order of Na⁺>H⁺>K⁺>NH₄ ⁺. A linear relationship with a slope of about —1 was obtained between log K _d and log[M⁺] above 0.1M (=mol/dm³). The retention volume (V _R ) of Cs in chromatography also decreased in a similar manner to K _d , depending on the kind of inorganic cations. The V _R value can be predicted from the K _d value based on the linear relation. The column efficiency was improved with fine particles of ferrierite, yielding the elution percentage above 95%.     

Role of some transition metal cations on the kinetics of thermal dehydration of synthetic zeolites

Zeolite was synthesized by the interaction of sodium silicate and sodium aluminate solution. The gel formed was purified and physico-chemically characterized. The gel was converted into different cationic forms, like, Ni²⁺, Co²⁺, Cd²⁺, etc., by ion exchange process. Isothermal dehydration kinetics of the hydrogel was studied from thermo-gravimetry. The gel dehydration reaction was observed to be low energy diffusion controlled process and the major part of the process followed first order kinetics. Exchangeable cations affected the kinetic parameters of the dehydration process.     

Nitrogen chemistry in coal pyrolysis: Catalytic roles of metal cations in secondary reactions of volatile nitrogen and char nitrogen

The present review focuses on elucidating the chemistry of nitrogen release during coal pyrolysis, in particular, on making clear catalytic roles of inherent Ca and Fe ions in not only the partitioning of volatile-N to tar-N, HCN, NH₃ and N₂ but also the conversion of char-N to N₂.     

Adsorption of Cu2+ Cations from Aqueous Solution by S-doped TiO2

S-doped TiO₂ as a novel adsorbent for Cu²⁺ cations removal from aqueous solutions was synthesized by simple sol-gel process. Removal of Cu²⁺ cations from aqueous solutions was investigated with particular reference to the effects of initial Cu²⁺ cations concentration, pH-value, adsorbent dosage, and temperature on adsorption. It was found that the maximum adsorption capacity was 96.35 mg g^?1 at 328 K. The adsorption equilibrium isotherms and the kinetic data were well described by the Langmuir and pseudo-second-order kinetic models, respectively. The high uptake capability of S-doped TiO₂ makes it a potentially attractive adsorbent for the removal of heavy metal pollutants from aqueous solution.     

一个新型钨铋酸盐与碱土金属离子配位的多酸化合物的合成和表征

一个基于[Bi2W20Cu2O70（H2O）4]10-缩写为：{Bi2W20Cu2}）阴离子和碱土金属离子的新型多酸化合物Ca2Na2H4[Bi2W20Cu2O70（H2O）4].42H2O通过Na12[Bi2W22O74（OH）2].44H2O（缩写为：{Bi2W22}）,CuCl2和CaCl2在水溶液中的反应被合成。标题化合物最大的特点是它代表了第一个钨铋酸盐与碱土金属离子配位的多酸化合物。通过单晶X射线衍射、红外光谱和元素分析对标题化合物的结构进行了表征。     

Mechanical Properties of Gellan Gels in Relation to Divalent Cations

Mechanical behavior of gels formed with gellan polymer crosslinked by calcium and magnesium ions was studied to determine the influence of divalent ion type and polymer concentration. Failure strength and deformation were measured in compression and related to concentrations of gellan and bound cations in gel matrices. Insufficient cations formed weak, extensible gels. Maximum gel strength was achieved at 0.5 divalent cations/repeat tetrasaccharide unit, assumed to be the condition for maximal numbers of complete junction zones. At optimum cation levels gels with Ca⁺⁺ were about 1.2 times stronger than gels with Mg⁺⁺ at the same polymer concentration. Excessive cations weakened the gels. Twice as much reduction in gel strength resulted from additional Ca⁺⁺ as compared to the same additional amount of Mg⁺⁺. Differences between strengths of the gels may be attributable to polymer configurations at junction zones in relation to cation size.     

A simple route for the synthesis of symmetrical thiourea derivatives and amidinium cations by reaction between isocyanides,amines and carbon disulfide

Reaction between primary amines and CS₂ promoted by alkyl isocyanides in ethanol as solvent provides a simple and efficient route for the synthesis of symmetrical thiourea derivatives. The reaction of secondary amines with carbon disulfide and alkyl isocyanides afforded new amidinium cations in good yields.     

饮料中六种金属阳离子的毛细管电泳分析

应用毛细管区带电泳(CZE)法测定了饮料中的6种金属阳离子。采用8mmol/L咪唑作为背景电解质,8mmol/La-羟基乙酸作为选择性改性剂,在pH4.0,分离电压为25kV,柱温为22℃的电泳条件下,采用间接紫外检测(214nm),在6min内分离测定了饮料中的K 、Na 、Ca2 、Mg2 、Sr2 、Zn2 等6种金属阳离子。方法快速、简便、灵敏度高、重现性好、测定成本低。     

金属离子浓度对泥沙淤积干重度影响试验研究

天然河流水体中的金属离子对淤积物干重度有很大影响。通过静水沉降试验初步研究了天然河水中常见金属离子Na+,Ca2+和Al3+对泥沙淤积干重度的影响。试验结果表明① 金属离子对泥沙淤积干重度的影响机理均相同,但是高价离子对泥沙淤积干重度影响大;② 离子对泥沙淤积干重度的影响可分为3个阶段,第1阶段干重度减小,第2阶段干重度增加并达到最大值,第3阶段干重度减小最后趋于不变;③ 在不同离子浓度范围内,泥沙浓度对干重度的影响不同;④ 离子浓度、泥沙浓度相同时,中值粒径越大干重度越大,且中值粒径大的泥沙干重度达到最大值所需离子少。     

The composite of carbon nanotubes and cobalt(II)-intercalated montmorillonite for enhanced electrocatalytic oxygen reduction

Abstract

Due to the rapid development of fuel cells, the fabrication of electrocatalysts for oxygen reduction (ORR) with high performance and low-cost is of great significance. Herein, cobalt cations-intercalated montmorillonite (Co-MMT) was prepared by a simple cation-exchange reaction between Na-MMT and cobalt cations. A detailed ORR investigation indicates that the as-prepared nanocomposite of Co-MMT and multiwalled carbon nanotubes (Co-MMT/MWCNT) exhibits better ORR catalytic activity in aqueous alkaline medium with a 4e-route mechanism than Na-MMT, Co-MMT and MWCNT, suggesting the synergistic effect between Co-MMT and MWCNT. Moreover, further research shows that Co-MMT/MWCNT hybrid demonstrated more positive onset potential for ORR, higher oxygen reduction peak current than commercial 5% Pt/C ORR electrocatalyst.