Study on negative pressure assisted hydrodynamic cavitation (NPA-HC) degradation of methylene blue in dye wastewater

The negative pressure is used to intensifying whole HC effect for enhancing the decolorization and mineralization of methylene blue (MB) in wastewater. Under the conditions of low temperature, high inlet pressure and moderate initial dye concentration, the negative pressure assisting HC (NPA-HC) system displayed a significantly enhanced degradation effect of MB than that of individual positive pressure HC system. For an efficient combination of 25 hole negative pressure orifice plate and 3 hole positive pressure orifice plate, the MB degradation ratios are 27.43% in NPA-HC system and 97.48% in NPA-HC+H2O2 (MB/H2O2 = 1.0:7.5 in molar ratio) system at 30 °C temperature in 10 mg/L MB solution, respectively.