Preparation of a novel chitosan-based magnetic adsorbent CTS@SnO2@Fe3O4 for effective treatment of dye wastewater

A novel chitosan-based magnetic composite CTS@SnO2@Fe3O4 was prepared by water-in-oil emulsification for adsorbing anionic dye RBR in aqueous solution. The physicochemical properties of the obtained material were characterized by MR, XRD, VSM, TGA, SEM and N-2 adsorption-desorption. Effects of contact time, solution pH, ionic strength, initial dye concentration and temperature on the adsorption of reactive brilliant red (RBR) were investigated via batch adsorption experiments. Compared with CTS@Fe3O4, CTS@SnO2@Fe3O4 showed better adsorption performance for RBR, represented by the adsorption capacity reaching a maximum of 981.23 mg/g at pH 2, illustrating that the introduction of SnO2 was beneficial for adsorption. The kinetic data and equilibrium adsorption behaviors were well depicted by pesudo-second-order kinetic model and Langmuir isotherm model, respectively. Evaluation of the thermodynamic parameters revealed that the adsorption process was spontaneous and endothermic. XPS analysis confirmed a potential adsorption mechanism that the N atoms on composite chelated with RBR ions in solution. In addition, CTS@SnO2@Fe3O4 particles were easy to be magnetically separated and had outstanding reusability after five times recycling. All in all, CTS@SnO2@Fe3O4 was proven to be an efficient and promising adsorbent for the dye removal due to its higher adsorption capacity compared with other adsorbents. (C) 2019 Elsevier B.V. All rights reserved.