Degradation of tetracycline using persulfate activated by a honeycomb structured S-doped g-C3N4/biochar under visible light

In this work, a novel S-doped g-C3N4/biochar (SCNBC) nanocomposite was fabricated to activate persulfate (PS) under visible light for tetracycline (TC) abatement. The maximum photocatalytic degradation efficiency of TC by the SCNBC/PS system exhibited 2.34 and 2.32 times of individual biochar (BC) and g-C3N4, respectively. This was mainly because the honeycomb tubular structure facilitated electrons transfer along the linear direction, favoring electron-hole (e(-)-h(+)) pair separation. Meanwhile, BC could serve as an electron reservoir to further inhibit e(-)-h(+) recombination. Radical scavenging tests and electron paramagnetic resonance measurement revealed that h(+) and O-2(center dot-) were the dominant oxidizing radicals in TC removal. Three possible degradation pathways of TC were proposed, the mechanism of which mainly included dealkylation, deamidation, dehydra-tion, hydroxylation and ring-cleavage reactions. Overall, this work provides a facile photocatalyst to activate PS for removal of organic pollutants.

Automated summary

A novel S-doped g-C3N4/biochar nanocomposite was prepared for the visible light-induced activation of persulfate to degrade tetracycline. The photocatalytic efficiency of this nanocomposite was 2.34 and 2.32 times higher than that of individual biochar and g-C3N4, respectively. The enhanced activity was attributed to the unique honeycomb tubular structure that facilitated electron transfer and the electron reservoir effect of biochar.