Experimental study on reduction of Cr (VI) by co-pyrolysis of polyethylene/chromite ore processing residue
ZHANG Da-lei1, LI Gong-wei1, LI Wei-hua1, KONG Hai-nan2, SUN Ying-jie1
1. School of Municipal and Environmental Engineering, Qingdao Technological University, Qingdao 266033, China;
2. School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
The influences of reaction parameters, including pyrolysis temperature, reaction time and the mass ratio of PE/COPR, on Cr (VI) reduction were evaluated. The change of chromium speciation during the treatment was studied by XANES and EXAFS spectroscopy. The results indicated that, (1) Through the co-pyrolysis treatment, the Cr (VI) reduction can be effectively reduced. When the temperature reaches 550℃, the reduction rate could reached to 99.93%. The Cr (VI) reduction rate gradually increased with the rising dose of PE and then became stable when the mass ratio was over 0.05. Cr (VI) reduction rate rapidly increased during the initial reaction time while almost unchanged after 6min. The optimum reaction condition was evaluated as below: pyrolysis temperature: 550℃, pyrolysis time: 6min, and PE/COPR: 0.05. (2) Cr2O3 as the reference material of Cr(III) is more accurate and reasonable than CrCl3 during the Cr(VI) detection by XANES, and the Cr(VI) in the COPR was reduced as amorphous Cr2O3. (3) Compared to the biomass, PE as the reducing agent can be more efficient in Cr(VI) reduction, ascribed to the higher content of C, H and no O. (4) Cr(VI) can be continuously reduced under continuous contact with the volatile compounds generated from the pyrolysis of PE.
张大磊, 李公伟, 李卫华, 孔海南, 孙英杰. 聚乙烯塑料/铬渣共热解还原Cr（VI）的实验研究[J]. 中国环境科学, 2017, 37(5): 1852-1857.
ZHANG Da-lei, LI Gong-wei, LI Wei-hua, KONG Hai-nan, SUN Ying-jie. Experimental study on reduction of Cr (VI) by co-pyrolysis of polyethylene/chromite ore processing residue. CHINA ENVIRONMENTAL SCIENCECE, 2017, 37(5): 1852-1857.
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