Adsorptive and photocatalytic removal of carcinogenic methylene blue dye by SnO2 nanorods: an equilibrium, kinetic and thermodynamics exploration

The present study reports a simple co-precipitation approach for the synthesis of SnO 2 nanorods. The SnO 2 nanorods were characterized by XRD, SEM, TEM, EDAX, SAED, and FTIR techniques, to examine their structural, morphological, functional group, and elemental properties. The findings of the SEM and TEM reveal the nanorod like morphology. For the adsorptive and photocatalytic removal of methylene blue dye from their aqueous solution the synthesized SnO 2 nanorods have been used. The effect on adsorptive and the photocatalytic removal capability of SnO 2 nanorods was examined by optimizing the various parameters such as pH, initial dye concentration, contact time and catalyst dose. Tha maximum adsorptive and photocatalytic removal of MB up to the 66% and 94% were obtained at pH = 7 and pH = 2, respectively. Besides, experimental adsorption results were used for the exploration of kinetics and adsorption isotherm (Langmuir and Freundlich), which shows that methylene blue adsorption over SnO 2 nanorods follows the pseudo-second-order kinetics with the rate constant K 2 is 1.1 × 10 −1 (g/mg/min) and obeys the Langmuir isotherm. However, the thermodynamic parameters were studied, indicating that adsorption is spontaneous and favorable. The adsorptive removal is an endothermic process and pointing towards the chemisorptions nature of the process. Graphic abstract