A Quantitative-Structure-Activity-Relationship (QSAR) model for the reaction rate constants of organic compounds during the ozonation process at different temperatures

Abstract

The ozonation process is an effective method for removing hazardous wastes in water. To better characterize and understand the factors influencing the reaction rate constants of organic compounds during the ozonation process, a quantitative-structure–activity-relationship (QSAR) model was developed using the principal component analysis and multiple linear regression (PCA-MLR) method. In principal component analysis, five of the seven components were found to mechanistically and statistically affect the reaction rate constants. Component 1 was represented by the number of oxygen atoms (nO) and minimum value of bond order (BOn), component 2 was represented by the energy of the highest occupied molecular orbital (EHOMO), and component 3 and 4 were dominated by the largest change in the charge of each atom during nucleophilic attack (f(+)x) and the energy of the lowest unoccupied molecular orbital (ELUMO), respectively. The temperature (T) was the most important factor for component 7. The optimal model was lnkO3=4.102+0.007T-3.419BOn+1.765f(+)x+5.698ELUMO-4.016EHOMO-0.241nO, with the following evaluation index values: squared correlation coefficient (R2) = 0.916, internal validation (q2) = 0.895 and external validation (Qext2) = 0.962. Based on these evaluation indices, Y-randomization validation and the definition of the applicability domain, the optimal model was stable, robust and predictive. We anticipate that our work will provide a credible theoretical foundation for estimating the reaction rate constants for degradation of high-molecular weight organic compounds during ozonation over a temperature range from 25 to 60 °C.