Intrinsic Chemiluminescence Generation during Advanced Oxidation of Persistent Halogenated Aromatic Carcinogens

Abstract

ABSTRACT:The ubiquitous distribution coupled with their carcinogenicity has raised public concerns on the potential risks to both human health and the ecosystem posed by the halogenated aromatic compounds (XAr). Recently, advanced oxidation processes (AOPs) have been increasingly favored as an "environmentally-green" technology for the remediation of such recalcitrant and highly toxic XAr. Here, we show that AOPs-mediated degradation of the priority pollutant pentachlorophenol and all other XAr produces an intrinsic chemiluminescence that directly depends on the generation of the extremely reactive hydroxyl radicals. We propose that the hydroxyl radical-dependent formation of quinoid intermediates and electronically excited carbonyl species is responsible for this unusual chemiluminescence production. A rapid, sensitive, simple, and effective chemiluminescence method was developed to quantify trace amounts of XAr and monitor their real-time degradation kinetics. These findings may have broad biological and environmental implications for future research on this important class of halogenated persistent organic pollutants.

Mechanism of Intrinsic Chemiluminescence Production from the Degradation of Persistent Chlorinated Phenols by the Fenton System: A Structure–Activity Relationship Study and the Critical Role of Quinoid and Semiquinone Radical Intermediates

“…27, 36 We found that this is also the case in our study. The major quinoid intermediates produced by TCPs were identified by HPLC-UV method with the respective authentic compounds as standards.…”

Why Does 2,3,5,6-Tetrachlorophenol Generate the Strongest Intrinsic Chemiluminescence among All Nineteen Chlorophenolic Persistent Organic Pollutants during Environmentally-friendly Advanced Oxidation Process?

“…During our study of metal-independent hydroxyl/alkoxyl/ketoxy radical production by halogenated quinones and H 2 O 2 (or organic hydroperoxides) 20 21 22 23 24 25 , and their potential biological effects 26 , we found that unprecedented hydroxyl radical-dependent two-step chemiluminescence could be generated by polyhalogenated quinones and H 2 O 2 23 . Recently, we also observed an intrinsic CL generation by all 19 chlorophenols (the parent compounds of chlorinated quinones) and the classic • OH-generating Fenton system, even in the absence of fluorescent agents 27 . One notable general trend is that the CL intensity increases with increasing number of chlorine atoms on the phenolic ring.…”

“…One notable general trend is that the CL intensity increases with increasing number of chlorine atoms on the phenolic ring. Interestingly and unexpectedly, the strongest CL emission was found to be produced by 2,3,5,6-TeCP, which is even stronger than the most-highly chlorinated PCP, and much more stronger than two other TeCP isomers (2,3,4,5-, and 2,3,4,6-TeCP) 27 . However, it remains unclear what is the underlying molecular mechanism.…”

Synthesis of magnetically separable Fe3O4@PANI/TiO2 photocatalyst with fast charge migration for photodegradation of EDTA under visible-light irradiation

“…Among these aqueous organic contaminants, EDTA is one of the most potentially dangerous http pollutants since it is used in many products such as herbicides, fertilizers, detergents, decontaminants in the nuclear industry, etc [1][2][3][4]. EDTA is widely used for water decontamination purposes in nuclear industry for its unique spatial conformation which can bind strongly to most metals.…”