Degradation of oil filed pollutants by hydrogen peroxide and persulfate activated over zero-valent metal

Nano zero-valent metal were prepared to activate hydrogen peroxide (HP) and persulfate (PS) for efficient degradation of hydroxypropyl guar gum (HPG) in oilfield water to avoid secondary contamination caused by transition metal ions in the homogeneous reaction. The effects of H2O2/Na2S2O8 concentration, catalyst concentration, temperature and pH on the degradation rate of HPG were comprehensively evaluated in this study. It was found that Cu0 coupled with HP or PS provided an effective treatment pathway which was based on rapid Cu0-mediated decomposition of the oxidants, resulting in complete removals by decreasing the (chemical oxygen demand) COD from 7350 mg/L to 360 mg/L, in particular when PS was employed as the oxidant. The HPG degradation rate was 81% at 45 ℃, pH 7, oxidant ratio of 2:3 (H2O2:Na2S2O8), total oxidant dosage of 10% and Cu0 dosage of 0.3 g/L. The results of this study demonstrated that the combined degradation of HPG pollutants by Cu0-activated H2O2/Na2S2O8 has a wide range of applications which provides new strategies and mechanism insights for advanced oxidation of oilfield pollutants.