Hydrodynamic cavitation degradation of Rhodamine B assisted by Fe3+ - doped TiO2: Mechanisms, geometric and operation parameters

In this paper, a novel method, hydrodynamic cavitation (HC) combined with Fe3+-doped TiO2, for the degradation of organic pollutants in aqueous solution is reported. The venturi tubes with different geometric parameters (size, shape and half divergent angle) are designed to obtain a strong HC effect. The structure, morphology and chemical composition of prepared Fe3+-doped TiO2 as catalyst are characterized via using XRD, SEM, TEM, XPS, UV-vis DRS and PL methods. The effects of added TiO2 (heat-treated at different temperatures for different times) and Fe3+-doped TiO2 (with different mole ratios of Fe and Ti) on the HC catalytic degradation of RhB are discussed. The influences of operation parameters including inlet pressure, initial RhB concentration and operating temperature on the HC catalytic degradation of RhB are studied by Box-Behnken design (BBD) and response surface methodology (RSM). Under 3.0 bar inlet pressure for 10 mg/L initial concentration of RhB solution at 40 degrees C operating temperature in the presence of Fe3+-doped TiO2 with 0.05:1.00 M ratio of Fe and Ti, the best HC degradation ratio can be obtained (91.11%). Furthermore, a possible mechanism of HC degradation of organic pollutants in the presence of Fe3+-doped TiO2 is proposed. Perhaps, this study may provide a feasible method for a large-scale treatment of dye wastewater.