Highly selective separation of Pb(II) with a novel aminophosphonic acid chelating resin from strong-acidic hexa-solute media

Abstract

The aminophosphonic acid chelating resin of PMAA-P bearing tertiary diphosphonic amine and amide groups, was newly prepared based on poly(methyl acrylate) and ethylenediamine. Due to the extra amide group and 4.64 mmol/g of high grafting molar mass of phosphonic acid groups, PMAA-P was found to combine with Pb(II) through ionic and coordinate bonds to form more stable tridentate and tetradentate coordination modes, resulting in much higher adsorption capacity and selectivity for Pb(II) than the commercial resin S950 even from strongly acidic media (pH 2.0). The maximum adsorption capacity of PMAA-P for Pb(II) was 1.548 mmol/g, exceeding that of S950 by 78.14%. Additionally, as to the hexa-solute system, PMAA-P showed the selectivity order of Pb(II) ≫ Cu(II) > Cd(II) > Zn(II) > Co(II) > Ni(II), with such high separation factors of αHMCsPb(II) as 5.45-+∞ and the high Pb(II) adsorption amount of 1.010 mmol/g, which was 77.19% higher than S950. Moreover, because of the strong replacement effect, the maximum effluent concentration of Ni(II) exceeded 123.60% of its influent concentration in dynamic separation tests. Furthermore, the adsorption amount of Pb(II) remained above 1.241 mmol/g after being regenerated for five cycles. Above all, PMAA-P has great potential in highly selective separation of Pb(II) from strong-acidic media and thus explores an efficient way of treating lead-acid battery wastewaters.