Self-cementation of the alkali-activated volcanic tuff coupling with thiol-functionalized expanded perlite that enhances the solidification and stabilization of the mercury-contaminated soil

Hg II contaminants tend to be soluble in the anoxic sediments, which would potentially deteriorate the traditional solidification/stabilization (S/S) process. The thiol-functionalized expanded perlite (thiol-Exp-p) was prepared and employed in the self-cementation of the alkali-activated volcanic tuff (VT) as both lightweight aggregate and adsorbent to enhance the S/S of the Hg-contaminated soil. The cementation experiments were comprehensively researched in a systematical design. The experiments of adsorption, self-cementation, coupling, and stability were subsequently configured and implemented to investigate the feasibility of the coupling system and to optimize the whole S/S process. Both the pseudo-first-order kinetic model and the intraparticle diffusion model were appropriate in fitting the dynamic adsorption of Hg II to thiol-Exp-p. CaO among the three alkali components had the most significant influence on the self-cementation of VT. The factors including the curing temperatures, the grinding times of VT, and the mass ratios of fly ash (FA) to binder all affected the coupling S/S process of Hg II -spiked soil. The compressive strengths gradually decreased over the dosage of soil samples ranging from 10% to 70% in the solidified blocks in the stability experiments with the leaching concentrations contrarily elevating in the range. The addition of thiol-Exp-p to the self-cementation of VT not only reinforced the stabilization of Hg II species in the solidified sample but also positively influenced the solidification process.