Efficient removal of organic pollutants in waste sulfuric acid by an advanced oxidation process using coconut shell-derived biochar to produce qualified poly aluminium sulfate

The waste sulfuric acid from the alkylation process contains numerous organic pollutants and seriously threatens the ecological environment. This study focused on the effective utilization of waste sulfuric acid to produce poly aluminium sulfate and deep degradation of organic pollutants in the Al2(SO4)3 solution through the advanced oxidation process. The coconut shell-derived and H3PO4-steam activated biochar (CBC) was used as the catalyst in the advanced oxidation process. The results revealed that the H3PO4-steam activation could introduce abundant acidic functional groups and enrich metal ions on the CBC surface, which served as the active sites and promoted H2O2 to form OH and HO2 radicals for efficient organic pollutant degradation. The treated Al2(SO4)3 solution with the colour removal of 96.2% and total organic carbon removal of 93.8% under the optimal reaction conditions was used to prepare the certified poly aluminium sulfate product. This study is of great significance in the valorization of waste sulfuric acid and the application of recycled agricultural residues in the advanced oxidation process.