The effect of the novel complexing agent in removal of heavy metal ions from waters and waste waters

The removal of Cu(II), Zn(II), Co(II), Ni(II), Pb(II) and Cd(II) from waters and industrial wastes in the presence of the novel chemical reagent N,N-bis(carboxymethyl)glutamic acid (GLDA) was investigated. The effect of surface properties on the sorption behaviour of studied complexes was investigated by FT-IR/PAS (Fourier transform-infrared photoacoustic spectroscopy) and SEM (scanning electron microscopy). The effects of contact time, concentration of the reagents and equilibrium pH of solution, temperature and presence of interfering ions on sorption of Cu(II), Zn(II), Co(II), Ni(II), Pb(II) and Cd(II) complexes with GLDA on the commercially available ion exchangers Lewatit MonoPlus MP 500, Amberlite IRA 958 and Diaion CR-20 were examined by batch and column techniques. It was found that pH of 9.0 was favourable for the sorption process, which followed the pseudo second-order equation. Of the sorption models used, the Dubinin–Radushkevich (D–R) model was found to be appropriate. The sorption was temperature-dependent as well as dependent on the presence of Ca(II), Mg(II), Cl−, SO42−, NO3− ions. The maximum sorption capacity (qe,exp) for Pb(II) complexes with GLDA on the polyacrylate anion exchanger Amberlite IRA 958 was found to be 99.80 mg/g. For the polystyrene anion exchanger Lewatit MonoPlus MP 500 the analogous value for Cu(II) complexes was as 81.62 mg/g. Therefore, it was found that GLDA is effective for the removal of Pb(II) and has the potential application for the purification of waters polluted by heavy metals. In the case of chelating Diaion CR-20, the decomposition of the sorbed complexes in the resin phase should be assumed.