Effects of some parameters on the removal of Cd(II) ions from aqueous solutions by polyethyleneimine–sodium xanthogenate

Abstract

A macromolecule flocculant polyethyleneimine–sodium xanthogenate, with the capacities of chelation, flocculation and precipitation for Cd(II) ions, was prepared. The effects of some parameters on the removal of Cd(II) by polyethyleneimine–sodium xanthogenate were investigated through flocculation experiments. The results showed that polyethyleneimine–sodium xanthogenate could remove Cd(II) ions effectively, and the removal rate of Cd(II) increased with the increase in pH. The maximum removal rate of Cd(II) increased from 88.5 to 99.7% at pH from 2.0 to 7.5. The presence of inorganic compounds (KCl, NaCl, CaCl2, MgCl2, NaF, NaNO3 and Na2SO4) in the solutions had less impact on the removal of Cd(II), while the existence of organic compounds (EDTA, CA, AA and TSPP) had significant influence on the Cd(II) removal efficiency. Furthermore, the existence of turbidity could improve the Cd(II) removal efficiency, and Cd(II) ions and turbidity in water samples were effectively removed simultaneously. The maximum removal rate of turbidity could reach 99.8%. The results of FTIR spectra and SEM indicated that the chelation between Cd(II) ions and dithiocarboxylic acid groups (–C(=S)–SH) on the molecular chains of polyethyleneimine–sodium xanthogenate was predominant for the removal of Cd(II), and adsorption bridging mechanism among the flocs also played an important role in the flocculation processes.