Enhancing the catalytic behaviour of HKUST-1 by graphene oxide for phenol oxidation.

The composites of graphite oxide (GrO) and the HKUST-1 framework were synthesized by the typical solvothermal method and applied as heterogeneous catalysts for catalytic wet peroxide oxidation (CWPO) of phenol. XRD, FT-IR, Raman and SEM were conducted to characterize the samples. For catalytic oxidation of 150 mL 100 mg L-1 phenol, the dose of 30 mg (0.2 g L-1) catalysts and 0.46 mL H2O2 were kept constant. The GrO-3/HKUST-1 (3% content of GrO) showed higher catalytic activity than the HKUST-1 framework and other GrO/HKUST-1 composites with 99% phenol conversion and 86% COD removal efficiency were obtained at 50°C after 30 min and 8 h. The effect of temperature (40-80°C) and pH (4-9) on catalytic oxidation of phenol by GrO-3/HKUST-1 was investigated. The results showed that the degradation of phenol was obtained with optimum efficiency at 60°C with complete phenol conversion and 93% COD reduction. Furthermore, the acid and alkali resistance abilities were enhanced to a certain degree by the integration of GrO compared with the parent framework HKUST-1. Three successive runs were conducted in the natural pH (6.8) of 150 mL 100 mg L-1 phenol solution which indicated that the synthesized GrO-3/HKUST-1 composite had satisfactory reusability due to the prevention of carbon deposit and negligible Cu2+ leaching (8 ppm). The GrO/HKUST-1 composite could be a kind of promising heterogeneous catalysts for catalytic degradation of organic compounds. Similar to other catalysts, the catalytic oxidation of phenol also relies on the formation of hydroxyl radicals.