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.

六价铬[Cr（VI）]的排毒和处理对于生态环境保护和人类健康具有真正的重要性。本文将Cr（VI）预先通过Fe ²⁺还原为三价铬[Cr ³⁺ ]。并通过碱活化和水热处理立即固定在基于“粉煤灰-偏高岭土”（FMB）的地聚合物中。用XRD，FT-IR和SEM对制备的脱毒Cr-Cr-FMB地质聚合物的相结构和微观结构进行了研究。还系统地研究了样品的抗压强度和Cr（VI）的浸出毒性。结果表明：水热处理后，样品的相组成主要由非晶相，石英，钠锌铁矿和氯化钠等几种弱结晶相组成。可以将脱毒后的Cr以化学键的形式固定在FMB地质聚合物的骨架结构中。另外，抗压强度试验结果表明，抗压强度主要受Cr添加和还原剂含量的影响。^将3+固定在FMB地质聚合物中后，很难再氧化为Cr（VI）。