Modified nickel–cobalt tailing activated PMS for highly efficient degradation of organic pollutants: Multiple-scale effect and active sites

The use of nickel–cobalt tailings rich in nickel, cobalt, and iron to produce catalytic materials that drive advanced oxidation systems for PMS is a sustainable strategy. This study uses a combination of alkali modification and calcination to prepare a novel waste-based PMS-AOPs catalytic material (NCT-β), and its catalytic activity against organic pollutants (RB-19, BPA, RhB, SMX, CBZ, and BA) was investigated under the activation of PMS, for first time. The characterization results showed that NCT-β was modified into a multi-layer honeycomb with irregular surface, which can provide abundant active sites for chemical reactions, and expose metal elements on the surface of the material, promoting the electron transfer efficiency of organic pollutant degradation. The degradation rate of NCT-β to RB-19 was 98.26 % within 30 min, and the catalytic efficiency was still more than 80 % when repeated use. Free radical pathway dominates the degradation process of organic pollutants, 1O2, ·O2, and ·OH are the main active radicals. Density functional theory (DFT) results indicate that the (0 2 0) crystal plane exposed by NCT-β is the strongest site of action for pollutants and PMS. This study provides a solution for developing green environmental functional materials based on solid waste and treating waste with waste.