Removal of Pb(II) ions from aqueous media using epichlorohydrin crosslinked chitosan Schiff's base@Fe₃O₄...

Lead is one of the highly toxic metals reaching the water bodies from industries and discarded domestic wastes. Chitosan and its derivatives can be used to modify magnetic materials to promote the adsorption properties of the magnetic materials for the removal of metal ions. The obtained ECCSB@Fe₃O₄ was characterized by XRD, FTIR, SEM, TEM and VSM analysis. The effect of solution pH, adsorbent dosage, contact time, initial metal ion concentration and temperature effect was studied. The results of the batch sorption kinetic experiments were substituted into the pseudo-first order, pseudo-second order and intraparticle diffusion models. The R² and SSE results show that pseudo-second order equation describes the sorption process very well. Adsorption process revealed that the initial uptake of Pb(II) was rapid and equilibrium was achieved within 105 min. Langmuir and Freundlich adsorption isotherm models were applied to represent adsorption isotherm data. The equilibrium data were well fitted by the Langmuir isotherm model by revealing the maximum sorption capacity value 86.20 mg/g of ECCSB@Fe₃O₄. Different thermodynamic parameters, namely, changes in standard Gibbs energy, enthalpy, and entropy, were also evaluated from the temperature dependence, and the results suggest that the adsorption reaction is spontaneous and endothermic in nature.