QSAR Study On The Degradation Kinetics Of Organic Pollutants In Fenton Process

Fenton method,as an advanced oxidation process for highly efficient treatment of refractory organic wastewater,has been a hot issue in the research domain of water treatment.Conventional Fenton research mainly includes:removal efficiency of specific organic matter or specific wastewater in Fenton reaction;exploration and optimization of Fenton oxidation reaction conditions;mechanism of Fenton oxidation reaction.However,there are a variety of organic compounds and they are complicated in structures.If Fenton oxidation experiments are carried out for each organism,it will bring huge time and labor cost.Quantitative structure-activity relationship?QSAR?research is a mature study dimension which is applied in biological toxicity research of organic compounds and drugs.By establishing the relationship between the activity of organic compounds and the quantification parameters of organic molecular structures,it is effective and accurate to predict the activity of new organic compounds.Based on studies above,this study aims to construct the relationship between Fenton reaction activity and the quantitative parameters of the molecular structure by means of quantitative structure-activity relationship?QSAR?In this paper,18 different types of organic compounds?such as Aniline,Bisphenol A and Orange G?were selected to be degraded by Fenton process at different temperatures.Chroma stands for the removal efficiency of organic matter.The first-order kinetics equation is utilized to match the reaction rate of the Fenton oxidation of organic matter at the initial stage.Meanwhile,the Arrhenius equation is employed to fit activation energy of Fenton reaction.Quantification parameters of the molecular structure of organic compounds calculated by scientific software are used as molecular descriptors to establish the quantitative parameter model between activation energy of Fenton reaction and molecular structure of organic matter.The main conclusions are as follows:?1?The Fenton oxidation method achieved a desirable effect on the removal of organic matter,and especially orange G and methyl orange demonstrates high removal rate in a short time.Increasing the reaction temperature is helpful to improve the removal rate of organic matter.Reaction Rate constant of organic matter is affected by the temperature.For the organic matter with higher reaction rate constant at room temperature,increasing the reaction temperature means a waste of energy rather than an increase in the reaction rate constant.However,when the temperature uplifts,the reaction rate constant increased exponentially for the organics with slow reaction at room temperature.Overall,warming is conducive to accelerating the reaction.?2?The Fenton reaction activation energy was positively correlated with 11 molecular descriptors,such as E_B3LYP,q?C^-?_min,Fukui index,and negatively correlated with?,E_GAP and other 9 molecular descriptors.The total energy of organic matter E_B3LYP is the most important influencing parameter of the activation energy.The weaker the electron-withdrawing ability of the carbon atom in the molecular system,the more difficult the reaction is,and the bigger the activation energy is.The amount of the activation energy is closely related to the active site of the reaction.?3?Based on multiple linear regression,relation model of Fenton reaction activation energy was established.According to whether the molecular descriptors include Fukui index,they are divided into two groups and models are established respectively.It is tested that Model 6 is the best:Ea=-133.571+0.024E_B3LYP+76.402q?C^-?_min+138.903BO_max+383.348f?0?_minin with R² being 0.873,R²_adj being 0.817 and SD being 10.445.And the fitting degree of the model is excellent.The results show that the model has good stability.External validation is Q²=0.952,and the model has good predictive ability in the activation energy of Fenton reaction.