Sodium tetraborate simultaneously enhances the degradation of acetaminophen and reduces the formation potential of chlorinated by-products with heat-activated peroxymonosulfate oxidation. (1st October 2022)

• Record Type: Journal Article
• Authors: Li, Jiawen; Zou, Jing; Zhang, Shuyin; Cai, Hengyu; Huang, Yixin; Lin, Jinbin; Li, Qingsong; Yuan, Baoling; Ma, Jun
• Is Part Of: Water research. Volume 224(2022)
• Publication Date: 2022-10-01
• Subjects: Peroxymonosulfate -- Heat activation -- Sodium tetraborate -- Monoperoxyborate -- Chlorinated by-products; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.119095
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Na2 B4 O7 improved the removal of acetaminophen in heat-activated peroxymonosulfate. 1 O2 and HO were the primary reactive species of acetaminophen removal. The generated HOOB(OH)3 − played a vital role in producing 1 O2 and HO . The toxicity of reaction solution declined significantly with acetaminophen removal. Na2 B4 O7 suppressed the formation of chlorinated by-products in Cl − -containing water. Abstract: In this study, sodium tetraborate (Na2 B4 O7 ) was introduced to enhance the degradation of acetaminophen (ACT) in heat-activated peroxymonosulfate (PMS) process. The elimination of ACT in Na2 B4 O7 /heat/PMS process followed the pseudo -first order kinetics. The corresponding kobs value with 10 mM Na2 B4 O7 was 33.1 times higher than that in heat/PMS process. 1 O2 and HO· were identified as primary reactive species via quenching experiments and electron paramagnetic resonance technology. B(OH)4 −, the hydrolysis product of Na2 B4 O7, reacted with PMS to generate HOOB(OH)3 − . 1 O2 was generated by the self-decomposition of PMS using B(OH)4 − as catalyst, while HO· was produced via the breakage of peroxide bond of PMS and HOOB(OH)3 − under high temperature. ACT was degraded by reactive species via the pathways of -NH- bond breakage, -OH replacement, -NH2 oxidation and benzene ring cleavage. Nine transformation intermediates were detected by LC/Q-TOF/MS, and the toxicity of reaction solution decreased significantly with the elimination of ACT. Increasing Na2 B4 O7 dosage, PMS concentration, initial pH and reaction temperature were conducive to ACT elimination. Humic acid, Cl − and CO3 2− inhibited the degradation of ACT heavily, while SO4 2− and NO3 − had the negligible effects. Moreover, B(OH)4 − could react with free chlorine to the inert B(OH)3 OCl − and further significantly suppress the formation of chlorinated by-products for the treatment of Cl − -containing water in Na2 B4 O7 /heat/PMS process. This study provided an effective way to enhance the oxidation capacity of heat/PMS process and suppress the formation of chlorinated by-products in chloride-containing water, and the findings had important implications for using borate buffer in the studies of PMS-based advanced oxidation processes. Graphical abstract: Image, graphical abstract