Strengthen Air Oxidation of Refractory Humic Acid Using Reductively Etched Nickel-Cobalt Spinel Catalyst

Nickel-cobalt spinel catalyst (NCO) is a promising for air oxidation of humic acid, which typical natural refractory organic matter and precursor toxic disinfection by-products. In this study, reductive etchers, NaBH4 or Na2SO3, were used to adjust the NCO surface structure increase performance. The modified (NCO-R) was characterized, relationship between its intrinsic properties catalytic paths discovered. results O2-temperature programmed desorption, NH3-temperature X-ray photoelectron spectroscopy (XPS) demonstrated that reductant etching introduced oxygen vacancies increased active species acidity. addition, modification did not change raw hollow sphere NCO. crystallinity specific area NCO-R increased, average pore size decreased. XPS showed ratio Co3+/Co2+ in decreased compared with NCO, while Ni3+/Ni2+ increased. H2-temperature reduction H2 ability stronger. Due these changes chemical physical properties, exhibited much better performance than acid at 25 °C, total carbon (TOC) removal rate significantly from 44.4% using 77.0% NCO-R. TOC concentration by 90.0% after 12 h 90 °C.