Hydrothermal processing, characterization and leaching toxicity of Cr-added "fly ash-metakaolin" based geopolymer
Hydrothermal processing, characterization and leaching toxicity of Cr-added "fly ash-metakaolin" based geopolymer
复制标题
添加Cr的“粉煤灰-偏高岭土”基地质聚合物的水热处理、表征及浸出毒性
DOI：
10.1016/j.conbuildmat.2020.118931
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发表时间：
2020
影响因子：
7.4
通讯作者：
Tan Hongbin
中科院分区：
文献类型：
--
作者：
Wei Yufeng;Wang Jin;Wang Junxia;Zhan Lei;Ye Xin;Tan Hongbin
六价铬（Cr(VI)）的脱毒处理对生态环境保护和人类健康具有重要意义。本文利用Fe2+将Cr（VI）提前还原为三价铬[Cr3+]，并通过碱活化和水热处理，将Cr（VI）立即固定在“粉煤灰-偏高岭土”基（FMB）地聚合物中。采用XRD、FT-IR和SEM对制备的脱毒cr - FMB地聚合物的物相结构和微观结构进行了表征。并对样品的抗压强度和Cr（VI）浸出毒性进行了系统研究。结果表明：经水热处理后，样品的相组成以非晶相为主，并有石英、辉石和氯化钠等弱晶相。解毒后的Cr以化学键的形式固定在FMB地聚合物的骨架结构中。此外，抗压强度试验结果表明，抗压强度主要受Cr添加量和还原剂含量的影响。重要的是，极低的Cr（VI）浸出浓度表明水热法制备的加Cr的FMB地聚合物具有优异的Cr（VI）浸出毒性，还原后的Cr3+被固定在FMB地聚合物中后难以再氧化为Cr（VI）。
The detoxification and disposal of hexavalent chromium [Cr(VI)] is of real importance to the ecological environment protection and human being health. In this paper, Cr(VI) was in advance reduced to trivalent chromium [Cr3+] by Fe2+and was immediately immobilized in a “fly ash-metakaolin” based (FMB) geopolymer through alkaline activation and hydrothermal processing. The phase structure and microstructure of the as-prepared detoxified Cr-added FMB geopolymer were investigated by XRD, FT-IR and SEM. The compressive strength and Cr(VI) leaching toxicity of the samples were also systematically investigated. The results showed that the phase compositions of the samples were mainly composed of amorphous phase, several weak crystalline phases of quartz, gismondite and sodium chloride after hydrothermal processing. The detoxified Cr can be fixed as the form of chemical bonding in the skeleton structure of FMB geopolymer. In addition, the compressive strength test results revealed that the compressive strength was mainly affected by the contents of Cr addition and reducing agent. Importantly, the extremely low leaching concentration of Cr(VI) suggested that the Cr-added FMB geopolymer prepared by hydrothermal processing possessed excellent Cr(VI) leaching toxicity, and the reduced Cr3+was difficultly reoxidized to Cr(VI) after being immobilized in the FMB geopolymer.