In this paper, phase equilibrium of Li+, Mg2+∥Cl-, SiO32--H2O system at 220°C was researched. The solid phases were characterized by X-ray diffraction (XRD). Lithium silicate, hectorite, karpinskite and magnesium hydroxide were observed as solid phases. According to the analysis of XRD, the phase diagram was obtained. The phase diagram could be used as the theoretical principle for synthesis of hectorite.

Phase diagram of MgCl2–LiCl–Na2­SiO3–H2O (MLSH) system at 200°C was reported. The phase diagram was designed according to the hydrothermal system in which hectorite was formed. The solid phases were characterized by X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Lithium silicate, hectorite and karpinskite were observed as solid phases. The presence of hectorite in solid phases was decided by the molar ratio of MgCl2 and Na2SiO3 in the system. When the Mg/Si molar ratio exceeded a certain value, little hectorite was formed even though there was a large amount of LiCl in the system. The reason may be that it was difficult for Li+ to replace the Mg2+ in the framework. As a versatile nanomaterial, hectorite could be synthesized using concentrated natural brine as starting materials by hydrothermal method at 200°C. The phase diagram could be used as the theoretical principle for synthesis of hectorite and comprehensive utilization of concentrated natural brine.

The term Zintl phase has been coined in honour of Edward Zintl,a German chemist.Zintl phases are formed by combinations of moderately electronegative post-transition elements,such as main group 13 and 14 elements with electropositive alkaline or alkaline-earth metals.In these combinations,owing to electron transfers (total or partial) from the electropositive to the electronegative elements,anionic frameworks are formed in solid state that range from isolated anionic clusters,rings,cages and 1,2 or 3-D extended structures of which clathrates are among the most remarkable.The authors discuss the correlation of salt lake resources and Zintl phases.The potential applications of Zintl phases in salt lake resources are briefly discussed.This strategy for the synthesis of solid state compounds,which comprised light elements of salt lake resources,main group 13 and 14 elements and transition metal,have unique magnetic,electronic,thermoelectric,colossal magnetoresistance and ferromagnetic properties.

The object of this work was to study the modified hectorite as effective adsorbent for Neutral Red (NR) from aqueous solution. The adsorbent capacity of modified hectorite was discussed. The effects of surfactant content, adsorbent content, pH and adsorption temperature on the sorption of NR on modified hectorite were studied. Experimental results showed that the equilibrium adsorption data fitted well with Langmuir isotherm and the adsorption capacity was 393.70 mg/g for the modified cetylpyridinium bromide hectorite (CPB-Hect). Kinetic studies showed that the dynamical data fitted well with the pseudo-second-order kinetic model. For thermodynamic studies, parameters such as the Gibbs free energy (ΔG0), the enthalpy (ΔH0) and the entropy (ΔS0) indicated that the adsorption process was spontaneous and endothermic in nature.

Some affecting factors including nitrogen oxides,absorbent cotton humidity of lead acetate,and temperature of absorption,on arsenic determination in complex system by Ag-DDC spectrophotometric method were studied in this paper.The results showed that the nitrogen oxides was difficult to be dispeled when using nitric acid to digest sulfide,which had negative interference on the arsenic determination.The hydrogen sulfide was absorbed much sufficiently by semi-dry absorbent cotton of lead acetate.The temperature of absorption liquid had also some interference on the determination,the absorbance decreasing with increasing temperature.

Two modified hectorites have been designed and synthesized by two cationic surfactants namely cetyltrimethyl ammonium bromide (CTAB) and octadecylamine (ODA) for selective removal of the anionic dye congo red (CR) from aqueous solution. The adsorbent capacity of modified hectorites was discussed and the optical contents of CTAB and ODA were 35% and 28%, respectively. Modified hectorites were characterized by X-ray powder diffractometer (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The effects of adsorbents content and adsorption temperature on the sorption of CR on modified hectorites were studied. Experimental results showed that the equilibrium adsorption data fitted well with the Langmuir isotherm and the adsorption capacities were 182 and 197mg/g for the modified cetyltrimethyl ammonium bromide hectorite (CTAB-Hect) and ammonium bromide hectorite (ODA-Hect), respectively. Kinetic studies showed that the dynamical data fitted well with the pseudo-second-order kinetic model. For thermodynamic studies, parameters such as the Gibbs free energy (ΔG0), the enthalpy (ΔH0) and the entropy (ΔS0) indicated that the adsorption process was spontaneous and endothermic in nature.

Spherical nanoparticles of Magnesium Lithium Silicate were synthesized hydrothermally using natural brine of Qaidam Salt Lake as starting materials. The concentrated brine was utilized directly without separating lithium or magnesium from brine at first. It is a good idea to make use of the salt lake resources in this region. The samples were determined by X-ray and TEM. The surface area and particle size were calculated.

Supported palladium catalysts for synthesis of MIBK from acetone with one step reaction were prepared by impregnation method. The influences of calcination teperature of various supports and La additive on the performance of catalyst were stutied.The surface of the catalysts was determined by BET method and Pd dispersion was determined by H\-2\|O\-2 titration. The results showed that calcination temperature of catalyst support at 1 023 K, and La additive were beneficial to the catalysis process and the catalysts preparation method should be acceptable for industrialization.

国防航空工业的发展需求高性能陶瓷,尤其是纳米陶瓷.聚有机硅倍半氧烷可作为前躯体,通过热解制备陶瓷.该方法操作简便,易于控制.本文综述了国外有关聚有机硅倍半氧烷热解理论与应用研究近况,并对这一领域的发展进行了展望.