Adsorptive performance of magnetic nano-biosorbent for binary dyes and investigation of comparative biosorption

The individual and competitive biosorption capacities of Metanil Yellow (MY) and Reactive Black 5 (RB5) by glutaraldehyde cross-linked magnetic chitosan nanoparticles (GMCNs) were studied. Competitive biosorption of the MY and RB5 dyes by the GMCNs has never been reported previously. Fourier transform infrared technique has been used to show the biosorbed MY and RB5 dyes onto GMCNs. During the studies, various essential factors influencing the biosorption, like adsorbate concentration, pH of the solution and contact time have been monitored. The equilibrium was achieved within 17 h for single dyes and 3 h for binary mixture at pH 3. The biosorption capacities were 620 mg/g for dye MY and 2549 mg/g for dye RB5 at pH 3, 30 °C. The second-order kinetic model has good compatibility with the dynamical biosorption behavior of a single dye and binary mixture. In order to study the competition biosorption of the RB5 and MY dyes in mixture solutions, the intraparticle diffusion model was used. Competition biosorption through analysis of the intraparticle diffusion model apparently favored the RB5 dye more than the MY dye on the GMCNs in mixture solutions. The biosorbent was regenerated efficiently through the alkaline solution and was then reused ten times for biosorption–desorption cycles.