Methylene Blue Adsorption by Novel Magnetic Chitosan Nanoadsorbent

Abstract

A novel magnetic nanoadsorbent (magnetic chitosan modified by N,N-bis (carboxymethyl) glutamic acid, G-MCTS for short) was prepared by covalent binding of tetrasodium of N,N-bis (carboxymethyl) glutamic acid onto the surface of chitosan-coated Fe3O4 nanoparticles. The adsorbent was characterized by scanning electron microscopy, infrared spectrum, vibrating sample magnetometer and X-ray powder diffractometer. It was found that G-MCTS had a spherical structure with a particle size ranging from 100 − 150 nm and a saturation magnetization value of 21 emu/g. Meanwhile, the adsorption performances of G-MCTS were tested with adsorption of methylene blue. Correspondingly, the adsorption effect factors (initial concentration, solution pH, contact time and temperature), adsorption kinetics, isotherms and adsorption thermodynamics were investigated in detail. Results showed that the adsorption could reach equilibrium within 30 min, besides, the adsorption kinetics accepted the pseudo-second-order kinetic model, and the adsorption isotherm data fit with Freundlich model as well as Langmuir model. More importantly, the maximum adsorption capacity was 3.3 g/g obtained by Langmuir model and the adsorption capacity was more than 90% of the initial saturation adsorption capacity after being used for four times. All of these results indicated that, G-MCTS can serve as an effective adsorbent for the adsorption of methylene blue.