Antioxidants accelerate the Fe(III)/Fe(II) cycle for the degradation of ofloxacin

Peroxymonosulfate (PMS) is widely used in advanced oxidation processes. Fe(II) is an excellent catalyst for PMS, and organic pollutants in water can be effectively degraded in the Fe(II)/PMS system. However, the pollutant degradation efficiency is limited by the low conversion efficiency of Fe(II). Natural antioxidants exist in the water environment and have strong electron-donating ability. At present, the research on the introduction of natural antioxidants into the advanced oxidation processes to degrade pollutants focuses on a few polyphenols, and the effects of other natural antioxidants on the removal of pollutants are worth studying. In this study, natural antioxidants, proanthocyanidins (PCs), saponins (SPs), and Lycium barbarum polysaccharides (LBPs), were introduced into the Fe(III)/PMS system. The reduction ability of natural antioxidants was used to improve the conversion efficiency of Fe(III) to Fe(II), and PMS was more effectively activated to produce ROS, which promoted the degradation of ofloxacin (OFL). After the introduction of PC in the Fe(III)/PMS system, 80% of OFL was degraded at 20 min, and 90% of OFL was degraded at 120 min after the introduction of SP. The experimental results showed that the degradation of OFL was affected by the amount of antioxidants, PMS and Fe(III), pH value, and coexisting anions. Free radical quenching experiments showed that ¹O₂, SO₄⁻·, and ·OH play an important role in the degradation of OFL in the Fe(III)/antioxidant/PMS system. This paper proves that the introduction of proanthocyanidins and saponins into the advanced oxidation processes can remove organic pollutants more efficiently.

Graphical Abstract