Study on the Mechanism and Effect of Iron Modified Coal Gasification Slag Passivation of Cadmium in Coal Gangue

Coal gasification slag (CGS) is an industrial solid waste with a porous structure and has the potential to be used as a heavy metal passivator. In this study, iron salt impregnation was used to modify CGS. FTIR and XPS characterization showed that iron modification doubled the number of hydroxyl active sites in CGS and introduced Fe-O groups to passivate Cd through complexation and co precipitation. In the passivation experiment, unlike other passivation materials that did not significantly increase the proportion of residual cadmium, the FGS prepared in this study has a unique advantage in increasing the proportion of residual cadmium, which can increase the proportion of residual cadmium in coal gangue by 39% and significantly reduce the mobility of cadmium. This study provides a new approach for the resource utilization of coal gasification slag. The iron modified coal gasification slag material prepared has the advantages of low cost and good environmental compatibility, which can provide technical support for in-situ remediation of cadmium contaminated soil and achieve "waste to waste" treatment.