Heavy Metal Ions Removal in the Presence of 1-Hydroxyethane-1,1-diphosphonic Acid From Aqueous Solutions on Polystyrene Anion Exchangers

In the presented paper, the ability of commercially available gel and macroporous polystyrene anion exchangers for the removal of copper(II), zinc(II), nickel(II), and cadmium(II) complexes with 1-hydroxyethane-1,1-diphosphonic acid (HEDP) from aqueous Solutions was investigated under various experimental conditions. In the experiments, the strongly basic anion exchangers Lewatit MonoPlus M 600, Lewatit MonoPlus MP 500, and Amberlite IRA 402 with the quaternary ammonium functional groups as well as the medium basic anion exchanger Lewatit MonoPlus MP 64 with the quaternary ammonium/tertiary amine functional groups were used. Special attention was paid to the concentration of heavy metal ions, M(II)-HEDP molar ratio, pH of solutions, temperature, and the physicochemical properties of the anion exchangers used. The effect of the interfered ions such as Ca(II), Mg(II), Cl-, NO3-, and SO42- on the efficiency of heavy metal complexes with HEDP sorption was also investigated. It was found that polystyrene anion exchangers rapidly sorbed the test metal complexes with HEDP, and the process became saturated in 20 min. The sorption kinetic data showed pseudo-second-order reaction kinetics rather than the pseudo-first-order kinetics. The adsorption behavior of Cu(II), Zn(II), Ni(II), and Cd(II) complexes with HEDP was studied in single as well as in multicomponent competitive systems. The obtained data were fitted well by the Langmuir adsorption isotherm model. Maximum sorption capacities for Cu(II), Zn(II), Ni(II), and Cd(II) complexes with HEDP Occurred for strongly basic anion exchanger Lewatit MonoPlus M 600 at the optimal pH 11.5 and were found to be 96.15, 80.64, 70.42, and 142.85 mg/g, respectively. For binary and quaternary metal complexes solutions, these values were smaller than those from single metal Solutions. The presence of Cu(II) and Zn(II) complexes more strongly inhibited Ni(II) and Cd(II) once sorption occured which indicates their greater affinity than that of the remaining complexes for the anion exchangers.