Browsing by Author "Xia, Zhipeng"

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    Gaseous CdCl2 and PbCl2 adsorption by limestone at high temperature: Mechanistic study through experiments and theoretical calculation
    (Elsevier, 2021-03-28) Zha, Jianrui; Zhu, Zhicheng; Huang, Yaji; Clough, Peter T.; Xia, Zhipeng
    There is a risk of heavy metal emission during solid waste incineration, and the capture of gaseous semi-volatile metal by mineral sorbents is an effective method for its pollution control. As a cheap and common additive for combustion industry, limestone is an effective sorbent for controlling various gaseous pollutants, but its high-temperature sorption mechanism for gaseous metal chlorides has not been systematically studied yet. In this study, an experimental study in a fixed bed furnace and density functional theoretical study were conducted to investigate the adsorption mechanism of gaseous CdCl2 and PbCl2 by limestone at high temperature. The capture performance was greater at a higher temperature due to the formation of an enhanced pore structure through limestone decomposition, while the efficiency decreased at temperatures higher than 700 °C because of the negative movement of the reaction equilibrium. Additionally, the higher equilibrium constant of CdCl2 caused more effective adsorption than PbCl2. According to theoretical calculations, both limestone and lime can adsorb molecular metal chlorides while lime has higher adsorption energies due to its more active surface. For a commercial application, it is recommended to inject limestone into the furnace at a high temperature to capture heavy metal more effectively.
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    Green production of a novel sorbent from kaolin for capturing gaseous PbCl2 in a furnace
    (Elsevier, 2020-09-22) Zha, Jianrui; Huang, Yaji; Clough, Peter T.; Xia, Zhipeng; Zhu, Zhicheng; Fan, Conghui; Yu, Mengzhu; Yan, Yongliang; Cheng, Haoqiang
    The pollution of semi-volatile heavy metals is one of the key environmental risks for municipal solid waste incineration, and in-situ adsorption of metals within the furnace by mineral sorbents such as kaolin has been demonstrated as a promising emission control method. To lessen the consumption of sorbent, a novel material of amorphous silicate was produced from kaolin through pressurised hydrothermal treatment. Its performance of gaseous PbCl2 capture was tested in a fixed bed furnace and compared with unmodified kaolin and metakaolin. With increasing temperature, the adsorption rates for all sorbents declined due to higher saturated vapour pressure, while the partitions of residual form lead increased which indicated higher stability of heavy metals in the sorbent because of melting effect. The new sorbent with a larger surface area and reformed structure presented 26% more adsorption efficiency than raw kaolin at 900 °C, and increasing the modification pressure improved these properties. Additionally, the production of this high-temperature sorbent was relatively inexpensive, required little thermal energy and no chemicals to produce and no waste effluent was generated, thus being much cleaner than other modification methods.