Treatment of fracturing fluid waste by Fentonreactionusingtransition metal complexes catalyzes oxidation of hydroxypropyl guar gum athigh pH

Hydroxypropyl guar gum (HPGG),polyacrylamide (PAM) and carboxymethyl cellulose (CMC)are widely usedasthickeners in fracturing fluids, and thus contaminate wastewater.We designed aclean oxidation process for the treatment ofwaste fracturing fluids containing hydroxypropyl guar gum and other polymers under high pH value. For that, 1,10-phenanthroline(L)-transition metal complexes were prepared and screened forviscosity reduction of hydroxypropyl guar gum oxidized by hydrogen peroxide (H2O2). Results show that Cu(II)L exhibited high catalytic performance for the degradation of hydroxypropyl guar gum in a pH range of 7-14. Under the optimum experimental conditions, the viscosity of hydroxypropyl guar gum solution can be reduced effectively with 10.0% H2O2 and 5.0% Cu(II)L. The chemical oxygen demand (COD) of the hydroxypropyl guar gum solution decreasedfrom 8 g/L to 65mg/L. Cu(II)L also showed a highcatalytic ability forthe degradation of various polymers.