1. 东北农业大学资源与环境学院，黑龙江 哈尔滨 150030 2. Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
Cr(Ⅵ) Adsorption Mechanism on Rice Husk Ash Burned at Low Temperature by Method of IR Spectra
FAN Chun-hui1，ZHANG Ying1*，ZHANG Ying-chao1，LI Jing1，Benny Chefetz2
1. School of Resource & Environment, Northeast Agricultural University, Harbin 150030, China 2. Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel
Abstract：Boehm titration method was used to analyze functional groups on cell surface of rice husk ash burned at low temperature in the present paper. Effects of initial pH value and temperature on Cr(Ⅵ) adsorption were studied, adsorption capacity was tested with the help of kinetic models and adsorption isotherms, instruments of Fourier transform infrared spectroscopy(FTIR) and scanning electron microscope(SEM) were used to check characteristics and adsorption mechanism of Cr(Ⅵ). The results indicated that optimal removing rate was achieved at initial pH value 5, and pH values of aqueous solution changed little before and after adsorption process. The adsorbent of rice husk ash could remove Cr(Ⅵ) effectively, and the maximum removing rate could be 95% with Cr(Ⅵ) concentration 20 mg·L-1 and achieve 1-2 level of state standard(GB8978—1996). The adsorption process fits pseudo-second-order kinetic model and Langmuir isotherm better, the maximum adsorption capacity of Cr(Ⅵ) was 3.277 6 mg·g-1. Results of FTIR showed that amide Ⅱ band, Si—O—Si, O—Si—O were important for Cr(Ⅵ) removal. SEM micrographs revealed that series of needle-shaped precipitation appeared on cell surface, and inorganic precipitation mechanism and redox mechanism might work in the test. As a kind of low cost adsorbent, rice husk ash can be applied to remove heavy metals in environment with great potential.
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