Adsorption characteristics and purification mechanism of solid waste based PRB composite particle fillers on Cd2+
Given that traditional permeable reaction barrier(PRB)fillers are expensive and susceptible to corrosion and passivation,this research prepared composite granular fillers(CGF)from steel slag,desulfurization gypsum,and others.The isothermal adsorption and kinetic characteristics of CGF on Cd2+were investigated,and the immersion experiment revealed the strength loss laws and dissipation features of CGF.The dynamic adsorption laws of CGF were explored by the dynamic adsorption experiment,and the purification mechanism of CGF on Cd2+was determined.The results show that the adsorption process of Cd2+by CGF is controlled by chemisorption and intraparticle diffusion,which is consistent with the PS-order model and Langmuir model.The T3 group has the best performance of CGF,with adsorption of 8.12 mg/g,a minimum 28-day dissipation rate of 4.98%,and a strength loss rate of 6.16%.Thomas model can well describe the dynamic adsorption behavior of CGF,the pump speed has the greatest influence on the penetration curve,and the dynamic equilibrium adsorption quantity qe increases with the increase of concentration and bed height.CGF can generate hydration products,such as C-S-H gel and AFt,through hydration reactions and volcanic ash reactions,which can provide particle strength while achieving the adsorption of Cd2+through coprecipitation and ion exchange.This study can provide a new method for the remediation of nonferrous metal mine-contaminated sites.
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