Browsing by Author "Cheng, Haoqiang"
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Item Open Access Dynamic transformations of metals in the burning solid matter during combustion of heavy metal-contaminated biomass(American Chemical Society, 2021-05-10) Zha, Jianrui; Huang, Yaji; Zhu, Zhicheng; Yu, Mengzhu; Clough, Peter T.; Yan, Yongliang; Dong, Lu; Cheng, HaoqiangCombustion as an efficient and reliable method is widely used for metal-enriched biomass to achieve energy and metal recoveries, but there are emission risks of heavy metals in the flue gas and bottom ash that can give rise to secondary pollutions. To optimize such combustion processes, this work investigated the combustion characteristics of a kind of hyperaccumulator biomass and focused on the intermediate states and dynamic transformations of metals for the first time. A pseudo-in situ sampling method was used to collect the burning solid residues at different time intervals before further analysis. The conversions between elemental forms were revealed, and their conversion rates were also calculated. It was found that the transformation of metals was determined by their elemental natures, species distributions, and combustion progress where there was not a consecutive process but separated by several stages, which were related to (1) the release of volatile matters, (2) the formation and consumption of the char, and (3) the fixation by silicates. Based on the information of dynamic metal characteristics, a new strategy was proposed to optimize metal distribution by adjusting the combustion time of operations. The methodology introduced in this work will also help emission control and metal recovery for other metal-rich fuels.Item Open Access 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, HaoqiangThe 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.