Investigation of the mechanism of phytate-modified biochar-catalyzed persulfate degradation of Ponceau 2R

Highlights

•	Changes in phytate modified biochar facilitate electron transfer.
•	Modified biochar was more effective than unmodified biochar in treating Ponceau 2R.
•	The reason for phytate-modified biochar to catalyze PMS may be the metaphosphoric acid.

Abstract

The mechanism of oxidation and degradation effect of phytate-modified biochar catalyzed persulfate on Ponceau 2R was investigated. Chemical-structural properties of phytate-modified biochar, such as surface morphology and surface oxygen-containing functional groups were characterized. The results suggest that modified biochar has better oxidation performance than unmodified biochar, and the modified biochar generated at 500 ℃ pyrolysis temperature can catalyze peroxymonosulfate (PMS) system with high efficiency, in large pH and temperature scope. And the degradation mechanism of Ponceau 2R by biochar-catalyzed PMS generation (BC-PMS) system was researched. It revealed that PBC300 (phytate-modified biochar pyrolyzed at 300 °C), PBC500 (phytate-modified biochar pyrolyzed at 500 °C), and PBC700 (phytate-modified biochar pyrolyzed at 700 °C) may have metaphosphoric acid linked to oxygen atoms and metaphosphoric acid linked in a bridging manner on the surface of biochar, catalyzing the production of hydroxyl radicals by PMS. PBC700 catalyzes the production of singlet oxygen by PMS through its structural defects, and singlet oxygen is the main catalytic product of PBC700.

Funding

The 13th Five-Year key research program of China(2017YFB0308303); Key Research & Development programs of Weiyang District, Xian(202043); Key Research & Development programs of Shaanxi Province(2018SF363)