Alternative synthesis for ZnFe₂O₄/chitosan magnetic particles to remove diclofenac from water by adsorption

An easy preparation of magnetic particles with a chitosan external layer and zinc ferrite as core material was proposed. ZnFe₂O₄/chitosan particles were produced without any calcination step, characterized in detail, and, for the first time, applied for diclofenac (DCF) uptake from aqueous solution. The magnetic properties were checked, and revealed that the adsorbent particles have ability to be separated from the solution by an external magnetic field. Adsorption of DCF onto ZnFe₂O₄/chitosan particles was a fast process, well represented by pseudo-second order kinetic model, favored at initial pH of 4, with 0.2 g L^-1 of adsorbent dosage and, reached the equilibrium within 20 min. The S-shaped equilibrium isotherms were well predicted by BET liquid-phase multilayer model. The adsorption was an exothermic, spontaneous and favorable process. The feasibility to produce chitosan magnetic particles, coupled with fast adsorption kinetics, high capacity (188 mg g^-1), reusability (4 times) and the possibility to employ ZnFe₂O₄/chitosan particles for DCF adsorption, even in more concentrated solutions, were positive outcomes of this study.