Polyamide-based magnetic graphene oxide nanocomposite for efficient Pb(II) removal from aqueous solutions

An aromatic polyamide (PA) containing imine and azo groups was synthesized successfully via a direct polycondensation reaction. Graphene oxide (GO) was prepared by a modified Hummers method. The GO surface was modified non-covalently with PA chains through the in-situ magnetization of PA and GO to prepare the PA@MGO as a novel nanocomposite. The preparation of PA@MGO nanocomposite was evaluated using different analysis techniques. The results showed that the introduced nanocomposite was successfully prepared with sphere-like nanoparticles and exhibited high saturation magnetization, as well as higher thermal stability compared to its components. The multifunctional nanocomposite served as a novel nanosorbent for the removal of Pb(II) from aqueous solutions, and various parameters, such as sorbent dosage, contact time, solution pH, initial concentration of Pb(II), and selectivity, were studied. The experiments showed that the removal efficiency and the adsorption capacity of PA@MGO (99% and 36.14 mg/g, respectively) were higher than those of each component at pH 6 with the same sorbent dosage. The pseudo-second-order kinetics and Langmuir isotherm models provided a proper explanation of the Pb(II) adsorption on PA@MGO. Additionally, the selectivity results showed that the Pb(II) removal process was not significantly affected in the presence of competing ions such as Na(I), K(I), Mg(II), and Al(III). The prepared nanosorbent was capable of up to 5 cycles for Pb(II) removal, without a noticeable decrease in removal efficiency (10%) and no structural changes. In this paper, we prepared a novel thermally stable magnetic nanosorbent for the selective Pb(II) removal from aquatic environments, featuring reusability properties up to five cycles, making it a potential material.