Micropollutant Degradation by the UV/H₂O₂ Process: Kinetic Comparison among Various Radiation Sources

Abstract

Kinetic comparisons of micropollutant degradation by ultraviolet (UV) based advanced oxidation processes among various radiation sources are an important issue, yet this is still a challenge at present. This study investigated comparatively the kinetics of sulfamethazine (SMN) degradation by the UV/H2O2 process among three representative radiation sources, including low-pressure mercury UV (LPUV, monochromatic), medium-pressure mercury UV (MPUV, polychromatic), and vacuum UV­(VUV)/UV (dual wavelengths causing different reaction mechanisms) lamps. Experiments were conducted with a newly developed mini-fluidic MPUV photoreaction system and a previously developed mini-fluidic VUV/UV photoreaction system. Measured and modeled results both indicate that the photon fluence-based SMN degradation rate constant (k p ′) followed a descending order of VUV/UV/H2O2 > MPUV/H2O2 (200–300 nm) > LPUV/H2O2, and the k p ′ of the MPUV lamp was dependent on the wavelength range selected for photon fluence calculation. Analysis of potential errors revealed that a shorter effective path-length could have a lower error, and the maximum errors for the MPUV/H2O2 and LPUV/H2O2 processes in this study were 7.7% and 18.2%, respectively. This study has developed a new method for kinetic comparisons of micropollutant degradation by UV-AOPs among various radiation sources at bench-scale, which provides useful reference to practical applications.

Role of Reactive Halogen Species in Disinfection Byproduct Formation during Chlorine Photolysis

“…Advanced oxidation processes (AOPs) such as chlorine − or hydrogen peroxide ,, photolysis are effective for oxidizing organic contaminants. These AOPs generate hydroxyl radical ( • OH), a highly reactive and nonselective oxidant that reacts with most organic compounds. − ,, Additionally, chlorine photolysis generates other reactive oxidants, including chlorine radical (Cl • ), dichloride radical anion (Cl 2 •– ), and ozone (O 3 ), via homolytic cleavage of free available chlorine (i.e., the mixture of hypochlorous acid and hypochlorite, referred to here as chlorine; Supporting Information Schematic S1).…”

“…As the impact of climate change becomes more profound, water scarcity will continue to increase, resulting in greater reliance on alternative water sources such as potable reuse options. 11 Advanced oxidation processes (AOPs) such as chlorine 12−15 or hydrogen peroxide 14,16,17 photolysis are effective for oxidizing organic contaminants. These AOPs generate hydroxyl radical ( • OH), a highly reactive and nonselective oxidant that reacts with most organic compounds.…”

A novel approach to interpret quasi-collimated beam results to support design and scale-up of vacuum UV based AOPs

“…S2 in SI). 1D graphs representing D total (or photon-fluence) versus log degradation of the OMP are currently employed to represent laboratory-scale results of AOPs ( Li et al., 2019 ). Dubowski et al., 2020 and Moradi and Moussavi, 2018 used plots of D UV vs. OMP degradation to represent degradation in a VUV+UV AOP.…”

Hemin functionalized hybrid aerogel-enabled electrochemical chip for real-time analysis of H2O2

“…The E ad of • OH on hemin is calculated to be 2.1 eV and the reaction is considered to be chemisorption (>0.8 eV). 43 The result indicates that • OH molecules can be readily adsorbed on hemin, promoting the occurrence of reaction (1). Besides, the deformation electron density (DED) map of the hemin-OH system reveals that electron deficiency could occur on the top of the Fe atom and electron enrichment could occur at the bottom of • OH (Fig.…”

“…Hydrogen peroxide (H 2 O 2 ), as the representative member of reactive oxygen species, plays an important role in various fields including chemical analysis, 1 pharmaceutical security 2 and food manufacturing. 3 In living organisms, H 2 O 2 is an important bio-regulatory molecule that is constantly produced, transferred and consumed by means of both physiological and pathophysiological pathways.…”