Removal of hazardous azo dye Metanil Yellow from aqueous solution by cross-linked magnetic biosorbent; equilibrium and kinetic studies

Abstract

In this study, glutaraldehyde cross-linked magnetic chitosan nanoparticles (GMCNs) were prepared through cross-linking modification of magnetic chitosan nanoparticles using glutaraldehyde as a cross-linker that exhibited excellent Metanil Yellow (MY) adsorption performance. The characterization of the GMCNs was performed by Fourier transform infrared spectroscopy, transmission electronmicroscopy, scanning electron microscopy, dynamic light scattering, and vibrating sample magnetometry analyses. Adsorption characteristics of MY from aqueous solution onto GMCNs have been studied. During the studies, various essential factors influencing the adsorption, like adsorbate concentration, amount of adsorbent, pH of the solution, and contact time have been monitored. The equilibrium was achieved within 17 h at pH 4, and the adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 625 mg/g and a Langmuir adsorption equilibrium constant of 5.2 × 10−4 dm3/mg at 25°C. The adsorption kinetics of MY at different initial dye concentrations was evaluated by the first-order and second-order models. The kinetic studies of MY adsorption showed that the adsorption process followed a second-order kinetic model. Furthermore, the GMCNs can be regenerated and reused through dye desorption in alkaline solution at pH 10. Adsorption results for reusability were 100, 93, and 65%, respectively, for three repeats.