Efficient degradation of tetracycline hydrochloride wastewater by microbubble catalytic ozonation with sludge biochar-loaded layered polymetallic hydroxide

The sludge biochar-loaded layered polymetallic hydroxide (SBC-LDH) containing Co-Mn-Fe was prepared, characterized and used as catalyst in microbubble catalytic ozonation (MB/O3/SBC-LDH) for tetracycline hydrochloride (TCH) removal from wastewater in this study. The performances of TCH removal and mineralization in MB/O3/SBC-LDH process were more efficient due to synergistic effect of microbubble ozonation and SBC-LDH catalysis, compared to other related treatment processes. The removal efficiencies of TCH and TOC under optimal conditions were 98.3 % and 59.6 % within 90 min in MB/O3/SBC-LDH process, respectively. The reactive oxygen species (ROS) oxidation enhanced in MB/O3/SBC-LDH process played a major role in efficient TCH removal, especially •O2– and 1O2. The electron supply of the contribution of oxygen-containing functional groups and metal ions on SBC-LDH surface was considered to promote ROS generation and their contributions were calculated as 54.51 % and 45.49 % in MB/O3/SBC-LDH process, respectively. The TCH degradation pathways were suggested and carbonylation attacked by •O2– and 1O2 was found to be the main mechanism of TCH degradation. Some TCH degradation intermediates seemed highly toxic, due to phenolic hydroxyl group or propionamide group probably. The removal of other antibiotics were also efficient in MB/O3/SBC-LDH process, demonstrating its promising application in antibiotic wastewater treatment.