Performance and heavy metal leaching of porous geopolymer based on solid wastes

To enhance the utilization efficiency of nickel slag (NS), lithium slag (LS) and metakaolin (MK), NS-LS-MK ternary porous geopolymer was prepared. The study was conducted to investigate the effects of varying raw material dosages and different curing conditions on the compressive strength, pore structure, phase composition, and microstructure of porous geopolymer. Additionally, the ability of NS-LS-MK porous geopolymer to immobilize heavy metals was examined. The experimental results indicate a decrease in compressive strength with increasing content of the foaming agent and foam stabilizer. The porosity increases by 3.96 % with an increase in water dosage from 6 % to 11 %. Compared with wet curing, the pore wall structure of porous geopolymer after dry curing is more uniform and presents fewer connected pores. The hydration products identified in the porous materials are primarily C-S-H and N-A-S-H compounds. Furthermore, the NS-LS-MK porous geopolymer demonstrates outstanding efficiencies in immobilizing heavy metals under diverse conditions, including acidic, alkaline, and saline environments. Notably, the immobilization rate for Cr can exceed 99.88 %.