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Regeneration performance of activated coke for elemental mercury removal by microwave and thermal methods

An, Donghai, Wang, Xiang, Cheng, Xingxing, Cui, Lin, Zhang, Xiaoyang, Zhou, Ping, Dong, Yong
Fuel processing technology 2020 v.199 pp. 106303
X-ray photoelectron spectroscopy, adsorption, carbon, carbon dioxide, carbon monoxide, desorption, heat, mercury, microwave treatment, moieties, nitric oxide, particle size, particle size distribution, physicochemical properties, pollution, sorbents, surface area
The purpose of this study was to recover mercury and reuse active coke in the field of active coke adsorption of Hg⁰. The powdered active coke (AC) with high adsorption performance of Hg⁰ was prepared by a simple way. The regeneration characteristics of AC as a Hg⁰ sorbent were also investigated using microwave (MG-AC) and thermal methods (TG-AC). Of the two regeneration methods, microwave heating exhibited a faster heating rate to achieve complete regeneration. Following regeneration, adsorption performance of regenerated AC increased due to AC reactivation by microwave. Brunauer-Emmett-Teller (BET) measurements, X-ray photoelectron spectroscopy (XPS), and Laser particle size analyzer were used to analyze surface physical and chemical properties as well as particle size distribution of the samples. The results indicated that regeneration could greatly influence properties of AC, such as specific surface area, pore structure, surface chemical functional groups, and average particle size. Thermal methods had higher desorption content (CO₂, CO and NO) than microwave methods. Hence, microwave regeneration had a smaller carbon consumption of 0.12% compared to thermal methods (0.23%). The Hg⁰ that desorbed from AC was collected using the deep adsorption technique in order to avoid secondary pollution.