Kaifeng Yu

Adsorption of Cr(VI) on micro- and mesoporous rice husk-based active carbon

The adsorption of hexavalent chromium from aqueous medium by rice husk-based activated carbon (RHC) was studied. The extent of adsorption was studied as a function of pH, contact time, contact temperature, adsorbate concentration and adsorbent with different pore structure. The removal of Cr(VI) by RHC was first introduced. The adsorption of two carbons activated by KOH-activation and NaOH-activation was discussed. The difference was studied through pore size distribution, pore volume and the adsorption capacity.

Synthesis and catalytic activity of stable hollow ZrO2–SiO2 spheres with mesopores in the shell wall

Stable hollow ZrO2–SiO2 spheres with mesopores in the shell wall have been successfully synthesized by a sol–gel process in an oil–water–oil microemulsion. The samples were characterized by transmission polarized light microscopy, SEM, TEM, and N2 adsorption–desorption isotherms. The characterization results indicate that a large number of mesopores are present in the shell wall of the calcined hollow ZrO2–SiO2 spheres, and that the diameter and shell thickness are ca. 50 and 15 µm, respectively. The hollow spheres exhibit high thermal stability and remain intact spherical structures even after calcination at 550 °C for 8 h. In the cracking reactions of cumene and 1,3,5-triisopropylbenzene the sulfated hollow ZrO2–SiO2 spheres show very high catalytic activities. Especially, the higher catalytic activity of 1,3,5-triisopropylbenzene cracking suggests the potential application in cracking of bulky molecules. A possible formation mechanism of hollow spheres of binary composite oxide is also proposed.