Heterogeneous degradation of oil field additives by Cu ( II ) complex‐activated persulfate oxidation

In this work, bentonite‐supported Cu(II) complex (B@Cu(II)L) was prepared by a one‐pot method and used as a heterogeneous catalyst for evaluating its catalytic activity in oxidation degradation of hydroxypropyl guar gum (HPGG) in oilfield wastewater. All of the reaction parameters effected degradation efficiency, such as Na2S2O8 concentration, catalyst amount, reaction temperature, and pH value, were investigated in detail. The results showed that the absolute viscosity of HPGG solution can be decreased from 15 to 1.48 mm2/s in presence of 15% Na2S2O8 (mass ratio to HPGG) and 1.5 g/L B@Cu(II)L at 45°C and pH = 10. It was also found that the chemical oxygen demand of HPGG solution catalyzed by B@Cu(II)L decreased from 4,080 to 584 mg/L after 240 min under the optimum experimental conditions. The catalytic activity of supported bivalent copper complexes over bentonite was gradually decreased due to the loss of the active copper.