ZIF-8 derived boron, nitrogen co-doped porous carbon as metal-free peroxymonosulfate activator for tetracycline hydrochloride degradation: Performance, mechanism and biotoxicity

Boron and nitrogen co-doped porous carbon material (B-NPC) derived from zeolitic imidazolate frameworks (ZIF-8) was well prepared, characterized, and performed as an excellent metal-free carboncatalyst to activate peroxymonosulfate (PMS) for tetracycline hydrochloride (TC) degradation. Almost 100% of TC was removed within 60 min using 10 mg B-NPC, 20 mg PMS at 25 ℃. The co-doping of boron and nitrogen significantly improved the catalytic performance of PMS activation. The co-doping of B, N not only provided abundant active sites, but also enhanced the specific surface area and porous structure. Furthermore, free radicals combined with the non-radical mechanism worked together in B-NPC/PMS system to efficiently degrade TC. The B species, pyridinic N and graphite N on carbon matrix played major roles in activating PMS and degrading TC. Coexisting ions, humic acid and water qualities barely affected TC degradation efficiency in B-NPC/PMS system. Metal-free B-NPC catalysts also showed excellent reusability and notable adaptability to various pollutants. Moreover, possible TC degradation pathways were proposed. The main intermediate and final products showed significant decrease in biotoxicity compared to TC. This study provides a novel strategy for designing efficient metal-free PMS activator to degrade antibiotics in wastewater.