[SnS] clusters modified MgAl-LDH composites for mercury ions removal from acid wastewater.

The high acidity of mercury ions (Hg) contained wastewater can complicate its safe disposal. MgAl-LDHs supported [SnS] clusters were synthesized for Hg removal from acid wastewater. The active sites of [SnS] clusters were inserted into the interlayers of MgAl-LDHs using an ion-exchange method. The experimental results indicated that [SnS]/MgAl-LDHs composite can obtain higher than 99% Hg removal efficiency under low pH values. The maximum mercury adsorption capacity is 360.6 mg g. It indicated that [SnS] clusters were the primary active sites for mercury uptake, existing as stable Hg(SnS) on the surface of the composite. Under low pH values, such a composite seems like a "net" for HgSO molecules, exhibiting great potential for mercury removal from acid solutions. Moreover, the co-exist metal ions such as Zn, Na, Cd, Cr, Pb, Co, and Ni have no significant influences on Hg removal. The adsorption isotherms and kinetics were also studied, indicating that the adsorption mechanism follows a monolayer chemical adsorption model. The [SnS]/MgAl-LDHs composite exhibits a great potential for Hg removal from acid wastewater.