Dual Role of Natural Organic Matter as an Inhibitor or Stimulator of Hydroxyl Radical Formation in the Ozonation Process
Year: 2025
Type: article
Abstract: The degradation of ozone (O 3 )-recalcitrant organic micropollutants (OMPs) is limited by the selectivity of O 3 toward electron-rich moieties. This study investigates the dual role of natural organic matter (NOM) in ozonation, focusing on its ability to inhibit or promote hydroxyl radical (HO • ) formation, thereby influencing the degradation of O 3 -resistant OMPs. Tannic acid (TA), gallic acid (GA), catechin (CAT), and tryptophan (Trp) were selected as NOM surrogates, representing phenolic, carboxylic, and amine functional groups. Atrazine (ATZ) served as a model OMP to evaluate the effects of NOM moieties, molecular weight, and concentration on degradation kinetics. During an initial phase (<20 s), aromatic, phenolic, and amine groups enhanced HO • formation, achieving 50% ATZ degradation, with over 85% achieved within 200 s. However, higher NOM concentrations (>5 mg/L) exhibited inhibitory effects due to increased O 3 depletion and radical scavenging. Phenolic moieties strongly enhanced ATZ degradation, with their effect increasing proportionally with concentration, while carboxylic groups, especially GA, scavenged HO •, resulting in low HO • yields (0.08–0.12) at 3–10 mg/L. These findings provide critical insights into the role of NOM functional groups in ozonation, advancing the understanding of O 3 demand, OMP fate, and process optimization in water treatment.
Source: ACS ES&T Water
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
Award: G7414727268
OpenAlex ID: W4413199187