Fe 3 O 4 -TiO 2 /chitosan nanobiocomposite as a novel cadmium adsorbent: Fabrication, characterization, equilibrium isotherms, adsorption kinetics, and thermodynamics study

Abstract

A new magnetic nanocomposite (MNC) was prepared by grafting 3-chloropropyltrimethoxysilane and melamine (CPMSi-Mel) onto the surface of Fe 3 O 4 @TiO 2 nanoparticles. Then, nanocomposite of chloroacetyl-chitosan (CACS) and (Fe 3 O 4 @TiO 2 -CPMSi-Mel) was fabricated from coprecipitation of CACS on the (Fe 3 O 4 @TiO 2 -CPMSi-Mel) nanoparticles. The synthesized MNC was characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, field emission scanning electron microscopy, transmission electron microscopy, CHN elemental analysis, thermogravimetric analysis, and vibrating sample magnetometer. The ability of MNC for removing heavy metal ion (Cd 2+ ) from polluted water was studied, and the effects of different parameters on the adsorption characteristics were investigated. The adsorption equilibrium data were well explained by the Langmuir isotherm model. The sorption kinetics was tested with pseudo-first-order and pseudo-second-order reaction and the rate constants of kinetic models were calculated. Results indicate that Cd 2+ uptake process followed the pseudo-second-order rate expression. Furthermore, thermodynamic studies specify that adsorption was spontaneous and endothermic. The adsorption mechanism onto MNC was controlled by electrostatic attraction between MNC and Cd 2+ . Excellent adsorption capacity with other advantages such as reusability, easy separation, and environment-friendly composition make them suitable adsorbents for removal of heavy metal ions from environmental and industrial wastes.