Mechanism of Fenton oxidation promoted by ball-milled carbon black and quantitative kinetic study of different oxygen functional groups

Regeneration of Fe²⁺ in the Fenton process using the catalytic properties of carbon materials to improve pollutant removal efficiency, but pure carbon materials have limited catalytic sites, and the modification conditions are complicated and costly. In this paper, more oxygen-containing functional groups were obtained by simple ball-milling treatment, and these functional groups adsorbed Fe³⁺ to the surface for reaction, accelerated the regeneration of Fe²⁺, and obviously enhanced the catalytic effect of carbon black. After 5 h, 7 h, 9 h, and 11 h of ball milling treatment to carbon black, the AO7 removal rates were 83 %, 68 %, 74 %, and 77 %, respectively. Through kinetic studies of Fe³⁺ reduction experiments, the secondary kinetic rates for oxygen-containing functional groups COOH, COOC, COH, and CO were quantitatively calculated as 0.00235–0.00288 µM⁻¹·min⁻¹, 0.00061-0.00086 µM⁻¹·min⁻¹, 0.00017–0.00034 µM⁻¹·min⁻¹, 0.006–0.00659 µM⁻¹·min⁻¹. Furthermore, kinetic analysis of small-pore activated carbon using the same method yielded similar results. It has been shown that this simple ball-milling method is useful for the addition of active sites to other pure carbon materials, as well as for determining the specific reaction equation for the reduction of Fe³⁺ by oxygen-containing functional groups on the surface of the material in the future.