TAML Activator/Peroxide-Catalyzed Facile Oxidative Degradation of the Persistent Explosives Trinitrotoluene and Trinitrobenzene in Micellar Solutions

Abstract

TAML activators are well-known for their ability to activate hydrogen peroxide to oxidize persistent pollutants in water. The trinitroaromatic explosives, 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitrobenzene (TNB), are often encountered together as persistent, toxic pollutants. Here we show that an aggressive TAML activator with peroxides boosts the effectiveness of the known surfactant/base promoted breakdown of TNT and transforms the surfactant induced nondestructive binding of base to TNB into an extensive multistep degradation process. Treatment of basic cationic surfactant solutions of either TNT or TNB with TAML/peroxide (hydrogen peroxide and tert-butylhydroperoxide, TBHP) gave complete pollutant removal for both in <1 h with >75% of the nitrogen and ≥20% of the carbon converted to nitrite/nitrate and formate, respectively. For TNT, the TAML advantage is to advance the process toward mineralization. Basic surfactant solutions of TNB gave the colored solutions typical of known Meisenheimer complexes which did not progress to degradation products over many hours. However with added TAML activator, the color was bleached quickly and the TNB starting compound was degraded extensively toward minerals within an hour. A slower surfactant-free TAML activator/peroxide process also degrades TNT/TNB effectively. Thus, TAML/peroxide amplification effectively advances TNT and TNB water treatment giving reason to explore the environmental applicability of the approach.

Removal of ecotoxicity of 17α-ethinylestradiol using TAML/peroxide water treatment

“…1) are full-functional, small molecule mimics of the peroxidase enzymes that at nanomolar concentrations (<100 nM) can decompose many micropollutants. For example, in laboratory studies, TAML/peroxide has been shown to efficiently degrade the persistent drug sertraline via its oxidative metabolites16, the recalcitrant pesticides trichlorophenol and pentachlorophenol17, thiophosphate pesticides such as fenitrothion18, dyes1920 and many other micropollutants21. Preliminary studies on U.K municipal wastewater show that TAML/peroxide readily degrades numerous pharmaceuticals14.…”

A multidisciplinary investigation of the technical and environmental performances of TAML/peroxide elimination of Bisphenol A compounds from water

“…TAML catalysts and TAML/H 2 O 2 processes appear to be environmentally benign based on a diversity of evidence [307][308][309][310] and, as further shown here, are extremely simple to deploy. TAML/H 2 O 2 processes have been employed to oxidatively destroy numerous targets in water, [311][312][313][314][315] including bromo-, 310 chloro- 309 and nitro- 316 phenols, drugs, 317 thiophosphate pesticides, 318,319 molluscicides, 320,321 nitroaromatics, 316,322 the B. atrophaeus noninfectious surrogate for pathogenic B. anthracis and protozoa, 323 dyes, [324][325][326][327] coloured paper industry effluents, 328 and signature oestrogenic micropollutants. 4,329,330 Importantly, 2/H 2 O 2 chemistry is comprised exclusively of biochemically common elements as a foundational strategy for avoiding toxicity.…”

Quantifying evolving toxicity in the TAML/peroxide mineralization of propranolol

“…In our execution of this study, propranolol is oxidized to near mineralization Our oxidation system is composed of hydrogen peroxide as the primary oxidant and an iron(III)-TAML peroxide activator (Figure 1), that closely replicates key steps of the catalytic cycles of peroxidase and cytochrome P450 enzymes (Collins, 2002;Collins et al, 2010, Collins andRyabov and Collins, 2009). In water, TAMLs catalyze the oxidation of a broad spectrum of molecules, including MPs (Kundu et al, 2013;Mills et al, 2015;Somasundar et al, 2020;Tang et al, 2016;Warner et al, 2020) according to Scheme 1. The mechanism in Scheme 1, when the oxidation is not complicated by extra phenomena , leads to the kinetic Equation 1.…”