Degradation of oxytetracycline by iron-manganese modified industrial lignin-based biochar activated peroxy-disulfate: Pathway and mechanistic analysis

Abstract

In this study, high-performance Fe-Mn-modified industrial lignin-based biochar (FMBC) was successfully prepared to facilitate the efficient degradation of oxytetracycline by its driven sulfate radical-based advanced oxidation process with 90% degradation within 30 min. The results showed that oxygenated functional groups (e. g. hydroxyl, carbonyl, etc.) in industrial lignin-based biochar, the synergistic effect of transition metals Fe and Mn, and defective structures were the active sites for activation of peroxy-disulfate. SO₄^·- produced during the degradation process assumed a key function. Significantly, 38 intermediates were innovatively proposed for the first time in the system, and oxytetracycline was degraded in 7 ways, including deamidation, demethylation, hydroxylation, secondary alcohol oxidation, ring opening, dehydration, and carbonylation. A new perspective on the application of industrial lignin in the advanced oxidative degradation of organic pollutants was provided by this study.

Keywords: Bimetallic modification; Biochar; Degradation pathway; Industrial lignin; Oxytetracycline hydrochloride.