Treatment of wastewater contaminated by mercury by adsorption on the crandallite mineral

Abstract

The present study has been undertaken to investigate a process that might remove inorganic mercury from mine waste water streams by using a compound of the crandallite type. In this work, an artificial amorphous crandallite, Ca 0.5 Sr0.5 Al3(OH)6(HPO 4)(PO4), was synthesized in our laboratory and studied for the separation, removal and recovery of mercury from mercurial wastewaters. Since this compound exhibits an extremely wide range of ionic substitutions, Ca and Sr were interchanged with mercury. As a result, the mercury content of the waste water, ranging initially from 70 to 90 mg l-1, was reduced to less than 0.1 mg l-1. The process has been studied under batch conditions. The crandallite has been shown to have a high capacity for the absorption of mercury from mercuric nitrate solutions. The exchange capacity values of crandallite range from 0.90-1.50 meq g-1. The equilibrium and kinetic behaviour was also studied. © 2005 Springer-Verlag Berlin Heidelberg.