Chitosan supported CoFe2O4 for the removal of anthraquinone dyes: kinetics, equilibrium and thermodynamics studies

Chitosan supported cobalt ferrite nanocomposite (Cs–CoFe2O4) was synthesized and characterized. The synthesized Cs–CoFe2O4 was used for the removal of Anthraquinone dyes (Methylene Green, MG and Reactive blue 4, RB4) from aqueous solution in batch processes. Kinetics data were subjected to pseudo-first-order and pseudo-second-order, Elovich and intra-particle diffusion models, while the equilibrium data were evaluated with Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The results of characterizations revealed that CoFe2O4 was successfully incorporated into the Cs, with resulting composite retaining its magnetic properties and the functional group in the Cs. Considering the closeness Qe(exp) and Qe(cal.), also the values of R2 and %SSE, the MG adsorption followed pseudo-second-order with average rate constants of 8.3 × 10−3 min−1 while the adsorption kinetic of RB4 is best described by pseudo-first-order model with average rate constant of 2.91 × 10−2 min−1. Langmuir adsorption isotherm fits gave R2 > 0.9 for both dyes with maximum adsorption capacities of 63.34 and 35.05 mg/g obtained MG and RB4 respectively. The thermodynamic parameters showed revealed spontaneous adsorption processes. The results indicated that the prepared Cs–CoFe2O4 is an efficient recyclable adsorbent for the MG and RB4 dye without losing the original activity and stability for water treatment applications.