ABTS as Both Activator and Electron Shuttle to Activate Persulfate for Diclofenac Degradation: Formation and Contributions of ABTS^•+, SO₄^•–, and ^•OH

Abstract

The activation of peroxydisulfate (PDS) by organic compounds has attracted increasing attention. However, some inherent drawbacks including quick activator decomposition and poor anti-interference capacity limited the application of organic compound-activated PDS. It was interestingly found that 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) could act as both activator and electron shuttle for PDS activation to enhance diclofenac (DCF) degradation over a pH range of 2.0–11.0. Multiple reactive species of ABTS•+, •OH, and SO4 •– were generated in the PDS/ABTS system, while only ABTS•+ and •OH directly contributed to DCF degradation. ABTS•+, generated via the reactions of ABTS with PDS, SO4 •–, and •OH, was the dominant reactive species of DCF degradation. No significant decomposition of ABTS was observed in the PDS/ABTS system, and ABTS acted as both activator and electron shuttle. Four possible degradation pathways of DCF were proposed, and the toxicity of DCF decreased after treatment with the PDS/ABTS system. The PDS/ABTS system had good anti-interference capacity to common natural water constituents. Additionally, ABTS was encapsulated into cellulose to obtain ABTS@Ce beads, and the PDS/ABTS@Ce system possessed excellent performance on DCF degradation. This study proposes a new perspective to reconsider the mechanism of activating PDS with organic compounds and highlights the considerable contribution of organic radicals on contaminant removal.

Single-Atom MnN5 Catalytic Sites Enable Efficient Peroxymonosulfate Activation by Forming Highly Reactive Mn(IV)–Oxo Species

“…As seen in Figure S28b, fresh MnN 5 showed no reactivity with ABTS. However, in contrast to MnN 5 -R (18%), MnN 5 -R0 could rapidly convert ABTS (54%) into the organic cation radical of ABTS · + , which had four characteristic adsorption peaks at 405, 640, 728, and 818 nm, further corroborating the formation of Mn­(IV) species on the MnN 5 -R0 surface and its dominant role in organic oxidation. The presence of Mn­(IV)–oxo species on the catalyst surface was also corroborated by XPS analyses.…”

In Situ Monitoring of the Polymerization Kinetics of Organic Pollutants during Persulfate-Based Advanced Oxidation Processes Using Plasmonic Colorimetry

“…Known as an endocrine disruptor, BPA has garnered widespread attention due to its reproductive and developmental toxicities, as well as its potential association with diabetes and thyroid dysfunction. − DIC, a nonsteroidal anti-inflammatory drug, has been detected in aquatic environments globally and recognized as an emerging contaminant. The hazardous effects of DIC residues on mammals and ecosystems are well-documented. − Persulfate-based AOPs have proven effective ways in removing both pollutants, − during which polymerization may take place.…”

Were Persulfate-Based Advanced Oxidation Processes Really Understood? Basic Concepts, Cognitive Biases, and Experimental Details

“…•− , eq 147), 491 or (iv) CoSO 4 and H 2 SO 4 solution, 492 to generate ABTS •+ . Green ABTS •+ possessed four characteristic absorption peaks at 415, 650, 732, and 820 nm.…”

“…•− besides ABTS •+ (eq 148). 491 Residual PS concentration could be measured using N,Ndiethyl-p-phenylenediamine (DPD) to produce DPD •+ . 494 DPD could also be oxidized by H 2 O 2 with the catalysis of horseradish peroxidase to produce DPD •+ .…”