QSAR models for the degradation of organic compounds in three pH conditions of potassium permanganate system

Abstract

a b s t r a c tPotassium permanganate oxidation is one of the effective water treatment processes applied to remove organic compounds, but structure variances of organic molecules and different water conditions result in different effects. To provide a complete understanding of potassium permanganate oxidation, it is meaningful to develop some relationships between reaction rate constants of organic compounds and structure of molecules in three conditions (acid, neutral and alkaline). In this study, 22 diverse organic compounds were measured for the reaction rate and Quantitative Structure Activity Relationship (QSAR) models were developed based on reaction rate constants of organic substances and 17 quantum descriptors. Quantum chemical descriptors were obtained by using Gaussian 09 and Material Studio 6.1, including μ, EB3LYP, q(CH + ), q(C -), q(H + ), E LUMO , E HOMO , bond order and Fukui indices. A set of 18 compounds were used as training set to develop models and 4 compounds were used as test set for external validation. Three optimal models were selected in three conditions, respectively. In the models, energy of the highest occupied molecular orbital (E HOMO ) and Fukui indices appeared in all the conditions, indicating the two quantum descriptors play the important role during the oxidation process. Based on the evaluation criteria, model 4 in the acid condition was recommended and exhibited optimum stability and predictive ability. The equation of model 4 is ln k' = 0.53 + 0.22 μ + 14.26 E HOMO + 4.89 q(H + ) -18.21 f(0) x , the results also indicate that the dipole moment (μ) is much more closely related to the value of ln k' than other quantum descriptors in potassium permanganate oxidation process.