Search

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: 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]

Abstract: Titanium silicon carbide (Ti3SiC2) ceramic was synthesized by in-situ reaction of metal titanium and polycarbosilane. Reaction mechanisms which lead to the formation of Ti3SiC2 were suggested on the basis of XRD analysis. The content of Ti3SiC2 reached 93% in products obtained from heating the Ti/polycarbosilane green compact at 1400 °C in Ar. The morphology and compositions of the products were examined by SEM equipped with EDX. The typical laminate structure of Ti3SiC2 particles with 1–4 μm in thickness and 4–15 μm in length was observed. EDX results showed that the atomic ratio of Ti:Si:C of grains is close to 3:1:2, which agrees with Ti3SiC2 composition. [Copyright &y& Elsevier]