The effects of the treatment conditions on metal ions removal in the presence of complexing agents of a new generation

The sorption of Cu(II), Zn(II), Ni(II), Cd(II) and Pb(II) ions in the presence of chelating agents of a new generation was carried out to investigate the sorption characteristics of Dowex M 4195. Influence of type and stability of sorbed complexes, sorption time, initial concentration, pH, temperature and the presence of interfering ions was estimated. For the two new biodegradable complexing agents: GLDA (tetrasodium salt of N,N-bis(carboxylmethyl)-l-glutamic acid) and EDDS (ethylenediaminedisuccinic acid) the mechanism of the sorption process was also proposed. The investigations in the single component system were conducted in the initial concentration range from 7.5 × 10− 4 to 2.5 × 10− 2 mol/L. The pH varied from 2.0 to 12.0, whereas temperature changed from 303 to 333 K. The adsorption data were fitted to the Langmuir, Freundlich, Temkin and Dubinin–Raduschevich models.The experimental results show that Dowex M 4195 has higher sorption capacity for heavy metal ions in the presence of EDDS than GLDA. The results also indicate that the Langmuir adsorption model was able to adequately describe the sorption of Cu(II), Zn(II), Ni(II), Cd(II) and Pb(II) ions on Dowex M 4195. The sorption followed the pseudo second order sorption kinetics.