Equilibrium and kinetic studies on acid dye Acid Red 88 adsorption by magnetic ZnFe2O4 spinel ferrite nanoparticles

A magnetic ZnFe2O4 (MNZnFe) was synthesized by microwave assisted hydrothermal method and was used as an adsorbent for the removal of acid dye Acid Red 88 (AR88) from aqueous solution. The effects of various parameters such as initial AR88 concentration (10–56 mg L−1), pH solution (3.2–10.7), and temperature (20–60 °C) were investigated. Prepared magnetic ZnFe2O4 was characterized by XRD, SEM, HRTEM, ICP-AES, BET, FTIR, and measurements of the magnetic susceptibility. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Langmuir model. Pseudo-first-order and pseudo-second-order kinetic models and intraparticle diffusion model were used to examine the adsorption kinetic data. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. Thermodynamics parameters, ΔG°, ΔH° and ΔS°, indicate that the adsorption of AR88 onto MNZnFe was spontaneous and exothermic in nature.

Figure optionsDownload high-quality image (169 K)Download as PowerPoint slideHighlights
► Magnetic ZnFe2O4 nanoparticles were used as an adsorbent for the removal of acid dye Acid Red 88.
► Adsorbent can be easily separated from the aqueous solution by an external magnetic field.
► Adsorption of Acid Red 88 onto ZnFe2O4 nanoparticles was favored at low pH.
► Adsorption of Acid Red 88 onto ZnFe2O4 nanoparticles was spontaneous and exothermic in nature.