Highly efficient removal of organic pollutants via a green catalytic oxidation system based on sodium metaborate and peroxymonosulfate.

The development of highly efficient and green catalytic oxidation process based on peroxymonosulfate (PMS) activation has been identified to be a significant yet challenging objective in the environmental catalysis field. A simple, environmentally benign and highly effective catalytic oxidation system was innovatively constructed by coupling NaBO 2 and PMS for the removal of Acid Red 1. The catalytic mechanism in the NaBO 2 /PMS system was elucidated by electron paramagnetic resonance (EPR) combined with several radical capture reagents (ascorbic acid, methanol, tert -butyl alcohol, ethanol and l -histidine). The experimental results indicated that singlet oxygen (1O 2) severed as the predominant reactive oxygen species (ROS) rather than the HO or Image 2 during the catalytic oxidation process, at variance with the reported radical pathway in the Co2+/PMS system. Inspiringly, p -benzoquinone (p -BQ) as a trapping agent in most advanced oxidation process could be turned into the positive one in the NaBO 2 /PMS system, achieving a nearly 3-times enhancement in terms of the rate constant for AR1 removal. More interestingly, sodium chloride (NaCl) presented the same enhancement effect as p -benzoquinone due to generation of hypochlorous acid (HOCl) and more 1O 2 , which was completely different from the reported. This study develops a highly efficient green oxidation process and opens up a new insight in the remediation of contaminated water. Image 1 • An environmental-friendly and highly effective catalytic oxidation system NaBO 2 /PMS was firstly reported. • Singlet oxygen was responsible for the efficient performance of this catalytic oxidation system. • Both the addition of p -BQ and NaCl could achieve nearly 3 times enhancement in contaminant removal. [ABSTRACT FROM AUTHOR]