Non-radical pathway dominated by singlet oxygen under high salinity condition towards efficient degradation of organic pollutants and inhibition of AOX formation

Abstract

It is still a challenge to effectively treat organic pollutants and control the formation of adsorbable organic halogens (AOX) under high salinity owing to the inevitable side reactions among chloride ions and reactive radicals. Herein, 3D N-doped graphene aerogel supported on nickel foam (NGA@NF) was designed for non-radical pathway through peroxymonosulfate (PMS) activation. The NGA@NF exhibits excellent catalytic activity with 92% removal of acid orange 7 (AO7) within 10 min under high salinity environment ([Cl-]0 = 200 mM), owing to the synergistic effects of 3D hierarchy porous structure and high nitrogen doping level (6.8%). Due to the superb resistance of singlet oxygen (1O2) to radical scavengers (Cl-), 78% of the total organic carbon (TOC) was removed in NGA@NF/PMS system, which is much higher than the traditional Co2+/PMS system (3%). Importantly, AOX value in NGA@NF/PMS system was 6.5 times lower than that in Co2+/PMS system. Kinetic calculation indicates that the effective inhibition of AOX formation could be attributed to the non-radical pathway with 1O2 as primary reactive species. This work highlights leveraging the non-radical pathway dominated by 1O2 to environmental remediation under high salinity conditions by a promising material.