Synergistic and antagonistic effects in simultaneous adsorption of Pb(II) and Cd(II) from aqueous solutions onto chitosan functionalized EDTA-silane/mGO

In the present work, EDTA-sinale as a chelating and claw-like substance grafted onto magnetic graphene oxide (mGO). The EDTA/mGO was subsequently functionalized by chitosan as a natural material with glucosamine backbone containing a high density of amino groups. The obtained nano-bio-composite was successfully characterized, and the magnetic field assisted adsorption was used for adsorption of Pb(II) and Cd(II) in single and binary solution in batch system. The optimum pH of 5 and sorbent dosage of 0.3 g/L were obtained in the singlecomponent adsorption for both studied ions. According to single-component adsorption, the maximum adsorption capacity of the CS/EDTA-silane/mGO was achieved to be 2.33 and 1.05 mmoL/g for Pb(II) and Cd(II), respectively, at optimum condition of pH and sorbent dosage. The adsorption kinetic models followed the pseudo-first order kinetic model (k(1,Pb(II)) = 0.2145 min(-1) and k(1,Gd(II)) = 0.0815 min(-1)). Thermodynamically, the adsorption of both metal ions was spontaneous and endothermic. The experimental data of binary adsorption show that the effect of Cd(II) on Pb(II) adsorption is synergetic exhibiting there is no competition between ions. Whereas, the effect of the co-existence Pd(II) on Cb(II) adsorption onto CS/EDTA-silane/mGO was found to be antagonistic/inhibition at higher molar concentration ratio of Pb(II).