Effects of biochar-based catalyst preparation on oxidation degradation of Ni-EDTA

Novel biochar-based catalysts using the lignin, collagen, and copper nitrate as raw materials were prepared by the co-pyrolysis method. Through the characterization by various techniques, the effects of preparation methods and process parameters on treatment of Ni-EDTA by catalytic wet hydrogen peroxide oxidation (CWPO) were investigated, and the deactivation mechanism of biochar-based catalyst was discussed. The results showed that the co-pyrolysis method was more favorable to the improvement of catalytic performance, homogeneous distribution and dissolution control of active component, exhibiting an increase of 13.05% and 16.63% in Ni and TOC removal efficiencies and a decline of 93.54% Cu leaching, respectively. Removal efficiencies of Ni (65.41%) and TOC (34.85%) were achieved after 60 min treatment at optimum conditions (i.e. calcination temperature of 800℃, Cu dosage of 10%, mass ratio of collagen to lignin of 1:3) and the corresponding leaching content of Cu was merely 1.7 mg·L^-1. Besides, the deactivation mechanism of the biochar-based catalysts herein involved the formation of carboxylic acid intermediates, leaching and valence state transformation of copper.