Production of Silicone Tetrachloride from Rice Husk by Chlorination and Performance of Mercury Adsorption from Aqueous Solution of the Chlorinated Residue

The production of silicone tetrachloride (SiCl4) from rice husk char by chlorination was investigated, and the effect of the char preparation temperature on SiCl4 volatilization and the coexisting element species in the char was examined. The behavior of chlorine (Cl) and the change in pore properties during char chlorination were analyzed, and the reaction mechanism was discussed. The performance of Hg ion removal of the chlorination residue was also investigated. At 1000 degrees C chlorination, the optimum rice husk pyrolysis temperature for attaining high ashrelease extent was 800 degrees C. Ash volatilization during char chlorination with heat treatment mainly occurred at >300 degrees C and reached a release extent of similar to 75% by 1000 degrees C. Si and P volatilization started at >300 degrees C and reached 70-75% by 1000 degrees C. In contrast, Na and K the volatilization occurred at >700 degrees C, with a 50% volatilization extent by 1000 degrees C. Mg and Ca had a volatilization rate of <20% by 1000 degrees C. When the char was held at 1000 degrees C, the release extent of Si and P reached 75-80% by 10 min. Na and K volatilized almost completely by 10 min, and the release extent of Mg and Ca increased with increasing holding time and became 10-50% by 60 min. The Cl content in the residue obtained at each chlorination temperature increased from 300 to 700 degrees C and then decreased with increasing temperature. The majority of CI taken up in the residue was an H2O insoluble form. The surface area and pore volume of the chlorinated residue tended to increase with increasing chlorination temperature, with the former increasing to 335 m(2)/g at 1000 degrees C and 10 min holding. The maximum mercury adsorption amount of the chlorinated residue obtained at 1000 degrees C, 10 min holding was 620 mg/g, indicating the mercury ion adsorption performance of the chlorinated residue.