Dithiocarbamate ligands as heavy metal expectorants from aqueous solutions

Abstract

The uncontrolled concentrations of heavy metals introduced into the water sources need an effective method for their removal. The dithiocarbamate (dtc) ligands are the most popular precipitating agents used for the removal of metals from wastewater. Presently, two novel dtc ligands, one without methylene linker (K2L1) and the other with methylene linker (K2L2) were used for the removal of eight heavy metals ions including Fe2+, Co2+, Ni2+, Cu2+, Cd2+, Ag+, Zn2+ and Pb2+ from the aqueous solution. These dtc ligands contain acyl (NH-C = O) and S, S (thiolate) functional groups. The results indicated that the metal removal efficiency of both ligands was almost 100% at pH 4 and 7 and free of the linker effect and acyl functional groups but depends on the S, S binding sites. It exhibited a distinct selectivity for the removal of metal ions (Pb2+ ∼ Cu2+ ∼ Ag1+ > Cd2+ > Co2+ > Ni2+ > Zn2+ > Fe2+). The developed methods have the potential for the removal of heavy metals and can be used for other thiophilic metals that are water-soluble. HIGHLIGHTS Water treatment, contaminated by heavy metal ions. Synthesis and characterization of two novel dithiocarbamate ligands. Effect of methylene (-CH2-) linker of dithiocarbamtes on heavy metals extraction. pH and temperature effect on the extraction efficiency of ligands.