Effective degradation of oil pollutants in water by hydrodynamic cavitation combined with electrocatalytic membrane

Hydrodynamic cavitation (HC) and electrocatalytic membrane (ECM) can be used in the oxidative degradation of oil pollutants, and a combined method with both techniques can improve the overall degradation efficiency. The results of this study show that HC could promote the dispersion and dissolution of oil in water at 35°C with an inlet pressure of 0.30 MPa and cavitation time of 2 h. Under these conditions, the oil concentration increased from initial 90 mg/L to 215 mg/L, at which point the effect of the degradation by HC could be clearly detected. Then, when the cavitation time was 5 h, the oil concentration decreased from maximal 215 mg/L to 139 mg/L. Subsequently, at a current density of 2 mA/cm2, pH 6, residence time of 3.8 min, electrode spacing of 40 mm and solution temperature of 30°C, the removal rate of oil pollutants reached up to 98.81%. Gas chromatography mass spectrometry (GC-MS) analysis shows that ECM could degrade oil pollutants more effectively. Therefore the combination of HC and ECM was demonstrated to be an efficient method for the removal of oil pollutants in water.