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Amino-functionalized mesoporous silica MCM-41 materials have been prepared to develop efficient adsorbents of Cr(VI) in wastewater, using silica fume as silica source. Functionalization with amino groups has been carried out by using grafting method. The materials have been characterized by means of X-ray diffraction (XRD), nitrogen (N2) adsorption-desorption, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Adsorption potential of the material for Cr(VI) removal from aqueous solution was investigated by varying experimental conditions such as pH, initial metal concentration, and contact time. The equilibrium data were analyzed using the Langmuir and Freundlich isotherm by linear regression analysis, and the results show that the adsorption equilibrium data obeyed the Langmuir model. In addition, the kinetics analysis revealed that the overall adsorption process was successfully fitted with the pseudo-second-order kinetic model. [ABSTRACT FROM AUTHOR]

Abstract: The dense ceramic part was prepared firstly using silazane with filler. The composition, structure and ceramic yield of silazane were characterized by elemental analysis, nuclear magnetic resonance (NMR), IR and thermogravimetric analysis (TGA). The ceramic yield was 63wt% upon pyrolysis at 1000°C under N2 atmosphere. The fabrication of ceramic part involved cross-linking of the silazane with metallic fillers (Ti particles) followed by a polymer-to-ceramic transformation step. Near net shape manufacturing of polymer derived ceramics could be achieved. The strength of ceramic parts could achieve 450±15MPa and scanning electron microscopy (SEM) observation showed that there was very low porosity on the fracture surface of pyrolysed body. [Copyright &y& Elsevier]

Abstract: Si–C–Ti ceramics were synthesized by reactive pyrolysis of polycarbosilane (PCS) precursor filled with metal Ti powder. Pyrolysis of mixture with atomic ratio of Ti:Si through 3:1–3:2 was carried out in argon atmosphere at given temperature up to 1500°C. The metal–precursor reactions, and phase evolution were studied using X-ray diffraction and scanning electron microscopy with EDX. The Ti3SiC2 phase was obtained firstly from reaction of PCS and Ti. Ti3SiC2 formation starts at 1300°C and its amount increases significantly in a narrow temperature range between 1400°C and 1500°C. In addition, addition of CaF2 can promote the formation of Ti3SiC2 phase. [Copyright &y& Elsevier]