Ultrasound catalytic ozonation to remove 5-hydroxy-1,3-phthalic acid from strongly alkaline and high-salt solutions: Aiding nuclear waste disposal and human health

Abstract

As a typical precipitation inhibitor and the main component of plasticizers, 5-hydroxy-1,3-phthalic acid (5-HPA) seriously threatens the nuclear waste disposal and human health. OH, 1O2, and O2− induced by the ultrasound catalytic ozonation (US/O3) process achieves a removal rate of 60.67 % of 5-HPA in strongly alkaline and high-salt solutions within 60 min, which is significantly higher than the O3 alone process. This technology is highly resistant to inorganic anions that coexist in industrial production, but the mineralization process is inhibited. Ozone utilization and mass transfer are significantly improved by ultrasound, including reducing the ozone bubble size by 38 %, increasing the ozone utilization rate from 52 % to 75 %, increasing the volumetric mass transfer coefficient by 61 %, and increasing the specific interfacial area by 60 %, reducing the molar ratio of ozone to TOC from 0.45 to 0.23. Through a combination of Density functional theory (DFT) and GC–MS, four pathways for removing 5-HPA are clearly proposed, which are significantly different from the evolution behavior in acidic systems. The US/O3 system has significant application potential in reducing the threat of 5-HPA to nuclear waste disposal and human health.