Degradation of humic acid using hydrogen peroxide activated by CuO-Co3O4@AC under microwave irradiation

Abstract To investigate the degradation of humic acid (HA) in a CuO-Co 3 O 4 @AC/H 2 O 2 system under microwave irradiation, a catalyst (CuO-Co 3 O 4 @AC) was prepared and characterized. The effects of several reaction parameters, such as the microwave temperature, initial pH, H 2 O 2 concentration, catalyst dosage and inorganic anions ( HCO 3 - and Cl - ) were investigated, and the synergetic effect of hydrogen peroxide among MW, AC and metal oxides was explored. The results indicated that cobalt and copper were supported on activated carbon and existed as Co 3 O 4 and CuO. The removal efficiency of HA and TOC reached 88% and 71%, respectively, with 100 mg/L HA, 80 °C, 9.8 mM H 2 O 2 and 0.5 g/L catalyst under 60 min of microwave irradiation. The existence of HCO 3 - and Cl - had an inhibitory effect on the degradation of HA, and the effect of HCO 3 - was more evident. Quenching experiments and EPR tests confirmed that OH and O 2 − were the main free radical species, and XPS analysis showed that the species present on AC were Co (II), Co (III) and Cu(II), which can activate H 2 O 2 to produce OH and O 2 − .