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Published on: February 21, 2017
Mechanism study of mechanochemical bromination on fly ash mercury removal adsorbent
Xinze Geng1, Yufeng Duan1, Shilin Zhao2
1Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, 210096, China.
Abstract:
Current approaches for Mechanochemical bromination (MCB) modified fly ash have been focusing on the efficiency and mechanism of mercury removal, but the MCB activation mechanism is still not clear. Selecting activated carbon (AC), hematite (He), anatase (An), and mullite (Mu) to simulate four main fly ash components, and the above samples were MCB modified by omni-directional planetary ball mill with NaBr crystal as modifier. Based on the physicochemical properties and mercury removal ability of each pure component before and after modification, the activation mechanism of MCB was obtained. The results indicate that single mechanochemical modification has almost no effect on the mercury removal ability of each component. The mercury removal ability of fly ash improved by MCB is mainly due to the C-Br generated by reaction between NaBr and AC, and the covalently bonded Br (M-Br) on He also provides a certain contribution. However, the contribution of An and Mu is a little. The MCB activation mechanism is verified that original AC and He are firstly converted into unsaturated carbon and He with surface lattice defects by MCB process, then react with Br free radicals to form C-Br and M-Br, while An and Mu do not mechanochemically react with NaBr during the MCB process.
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