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 FTIR, XRD, VSM, TGA, SEM and N2 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.