Highly efficient methylene blue dyes removal from aqueous systems by chitosan coated magnetic mesoporous silica nanoparticles

Abstract

In this work, uniform chitosan coated magnetic mesoporous silica nanoparticles (CMMSNs) with good adsorption capacity and magnetic response were synthesized, and they were successfully applied to highly efficient methylene blue (MB) dyes removal. The structure and morphologies of the obtained nanoparticles were characterized by Fourier transform infrared spectroscop, X-ray diffraction, thermogravimetric analysis and nitrogen adsorption–desorption analysis and transimission electron microscopy. The CMMSNs possessed a classical core–shell structure with several Fe3O4 contained in mesoporous silica nanoparticles, and then coated by chitosan. The CMMSNs had a saturation magnetization of 12.6 emu g−1 and could be easily separated by a magnet. Taking MB as a typical organic dye, the CMMSNs were subjected as adsorbent to remove them from the polluted water. The saturated adsorption capacity of MB was 43.03 mg g−1. The MB adsorption kinetic and adsorption isotherm analysis results showed that the pseudo-second order equation was the most suitable one to describe the adsorption kinetics of MB for CMMSNs, and the adsorption isotherm model of MB onto the CMMSNs belonged to Freundlich isotherm model.