Enhanced heavy metal ions adsorption by 4‑aminobenzoic acid grafted on chitosan/epichlorohydrin composite: Kinetics, isotherms, thermodynamics and desorption studies.

The multi-functional chitosan is important for the development of novel adsorbents which is needed for the effective removal of scavenging metal ions from water and wastewater. In this study the functionalized materials were characterize by FTIR, SEM/EDX, TGA/DTA, BET and XRD. Physicochemical parameters including pH, contact time, ionic strength and temperature were investigated in batch mode to optimize the conditions to be applied on a commercial scale for the maximum removal of metal ions using batch applications. The results showed that adsorption performance of grafted cross-linked chitosan beads can be modeled efficiently by Langmuir isotherm and pseudo-second order kinetic model. Thermodynamic parameters such as Gibb's free energy change (∆G°), enthalpy change (∆H°) and entropy change (∆S°) were calculated and the results showed the adsorption of Pb(II), Cu(II), Ni(II), Zn(II) and Cd(II) ions onto grafted crosslinked chitosan beads (G/ECH-CS) are spontaneous and endothermic in nature. Batch regeneration of the spent adsorbent from the single component mixture was effective. Multiple adsorption/desorption experiments were also carried out, and it was found that 0.0% mass loss of the G/ECH-CS was observed after the third cycle of adsorption/desorption studies.