Photocatalytic Degradation of Methylene Blue (MB) and Methyl Orange (MO) by the Highly Oxidative Properties of SnO₂–Sb₂O₃ Particles

Abstract

SnO₂–Sb₂O₃ particles, with various Sb₂O₃ mole fraction (x) ranging from 0 to 1, have been synthesized by a sol-gel method. Tin oxalate and antimony chloride were used as the metal precursors, water as the solvent, citric acid as the pH modifier, and triethanolamine as a stabilizing agent. The effect of the chemical composition of the synthesized catalyst on the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) was evaluated. It was established that a SnO₂–Sb₂O₃ (Sb₂O₃ mole fraction of x = 0.15) catalyst presents a highly oxidative power to degrade a 20 µM MB solution until 98.60%, using a UV lamp of 254 nm and 6 W. The kinetics of the SnO₂–Sb₂O₃ (x = 0.15) photocatalytic oxidation was monitored as a function of the initial concentration of MO (100, 200, 300, and 400 µM) at different reaction times. It was found that the reaction probably presents a pseudo-first-order kinetic model. The effect of the intensity of the power lamp was studied, finding an increment from 16.32 to 98.42%, for UV lamps of 6 W and 72 and 1200 mW cm⁻², respectively. Finally, the effect of temperature (298, 318, 328 and 338 K) was analyzed, and the activation energy from Ea = 7.2 kcal mol⁻¹ was determined.