Prediction of reaction rate constants of hydroxyl radical with chemicals in water

Abstract

The rate constants (kOH) of the reactions between organic micropollutants with hydroxyl radical (•OH) in aqueous systems are an important parameter to evaluate the persistence of organic compounds in the environment. In this paper, a support vector machine (SVM) model based on five descriptors was built to predict the reaction rate constants (log K = (log kOH)/MW). The quantitative structure–activity relationship (QSAR) model of log K was obtained from a training set (600 compounds) and validated with a test set (395 compounds). The coefficients of determination R2 of the training and test sets are 0.923 and 0.925, respectively. The results suggest that the SVM model developed in this work possesses satisfactory prediction ability. Practitioner points The rate constants of the reactions of organic micropollutants with •OH in aqueous systems were investigated. SVM model was established for the reaction rate constants (log K = (log kOH)/MW). Only five molecular descriptors were used to predict 995 log K. A large data set was used for the test set (395 compounds).

Interpretable Machine Learning and Reactomics Assisted Isotopically Labeled FT-ICR-MS for Exploring the Reactivity and Transformation of Natural Organic Matter during Ultraviolet Photolysis

“…The developed network decoded the possible transformation of NOM in terms of both the structural category (Figure ) and the molecular composition (Figure S5). The reaction system was most likely dominated by relatively simpler reactions (as indicated by the successful application of PMD network analysis , ) such as hydroxylation (i.e., [+OD-H], [+D 2 O 2 ], [+2OD-2H], and [+3OD]) and substitution of nitro groups (i.e., [+OD-NH 2 ], [+D-NH 2 ], and [+D-NO 2 ]), with a relatively small contribution of carbon elimination reactions (i.e., [-CH 2 O], [-CH 2 ], [-C 2 H 4 ], [-C 3 H 6 ], and [-CO 2 ]), including ring-opening reactions (which is also indicated by an insignificant AI mod decrease).…”

“…developed network decoded the possible transformation of NOM in terms of both the structural category (Figure 3) and the molecular composition (Figure S5). The reaction system was most likely dominated by relatively simpler reactions (as indicated by the successful application of PMD network analysis 41,64 Hydroxylation with hydrogen substitution (+OD-H) was found to be the dominant reaction for lignin/CRAMs and condensed aromatics with 1267 (28.7%) and 132 (23.6%) formulas, respectively. Meanwhile, the loss of a nitro group (+D-NO 2 ) in the UV reactions was 281 (37.1%) formulas for tannins.…”

Performance of TiO2/UV-LED-Based Processes for Degradation of Pharmaceuticals: Effect of Matrix Composition and Process Variables

“…It can be observed how the pollutants were degraded differently in the treatments. The degradation depends on: (1) the types and amount of available oxidative species; (2) the PhACs' respective reactivity with each of the generated oxidative species [5]; (3) the interaction between the PhACs and the catalyst surface (adsorption) [56]; (4) the ionic state of each PhAC in solution (there might be distinct reactivity for the same parent compound for both photolytic and photocatalytic routes); (5) PhAC absorption spectrum and quantum yield for a given wavelength (specific for photolysis) [57,58]. Most of these points depend, directly or indirectly, on the matrix composition and pH [59].…”

“…Water scarcity across the globe demands an effort to find efficient and sustainable treatments that will allow its safe reuse [1,2]. Furthermore, pharmaceutical active compounds (PhACs) are commonly found in wastewater treatment plant outlets, since some of them are resistant to conventional physical and/or biological treatments [3][4][5][6]. PhACs may then end up in waterbodies, persist in the environment and bio-accumulate, causing diverse sorts of endocrine disruptions in aquatic life, even at very small concentrations (ng/L, µg/L) [7,8].…”