Advanced Oxidation Of Refractory Organic Pollutants With H₂O₂ And O₃ And Their Quantitative Structure- Activity Relationships

Ozone/hydrogen peroxide oxidation is a composite advanced oxidation technology based on single advanced oxidation technology,whose process includes both the direct oxidation by ozone and the indirect oxidation by hydroxyl radicals.In the consideration of oxidation electrode potential,hydroxyl radical?2.80V?is higher than ozone?2.07V?,and that means both of them are strong oxidants.The addition of H₂O₂ to ozonation can accelerate the decomposition of hydroxyl radicals.The synergistic effect of both O₃ and H₂O₂ greatly improves the oxidation efficiency.Therefore,the ozone/hydrogen peroxide oxidation process can effectively treat the refractory organic wastewater.This paper mainly studied the degradation effect of 23 kinds of refractory organic,such as bisphenol A,?o-,m-,p-?anilinesulfonic acid,?o-,m,p-?nitroaniline,through H₂O₂ oxidation,O₃ oxidation and O₃/H₂O₂composite oxidation.With the change of hydrogen peroxide dosage?1mL,2mL,4mL,8mL?,the color removal rate constants and TOC removal rate constants were studied.We also discuss the correlation between the quantum chemical structure descriptors of organic compounds and their K_color and K_TOC.At the same time,we construct 2D-QSAR models for K_color and K_TOCOC and 3D-QSAR models for K_color.In brief,we can draw the following conclusions:?1?Based on the results of color degradation of organic compounds,it was found that the oxidation capacities of the three oxidation methods were as follows:single H₂O₂ oxidation<<single O₃ oxidation<O₃/H₂O₂ oxidation.Hydrogen peroxide oxidation of organic matter had a low color removal rate,its degradation efficiency increases with the hydrogen peroxide dosage,the highest average removal ratio is 5.86%.The color removal ratio of organic matter with ozonation and ozone/hydrogen peroxide oxidation were better.After 60min reaction,21 of 23 organic compounds have a removal ratio of more than 80%.The degradation of 23 organic compounds by O₃ oxidation and O₃/H₂O₂ oxidation agrees with the pseudo first-order kinetic model.?2?The TOC degradation rate of organic matter is lower than the color degradation rate of that.The TOC degradation rate of ozone/hydrogen peroxide oxidation organics increased with the hydrogen peroxide dosage.The TOC degradation rate of organic compounds by O₃ oxidation ranged from 4.69%to 45.45%,and which by O₃+8 mL H₂O₂ oxidation ranged from10.16%to 58.88%,It shows that hydrogen peroxide can promote ozone oxidation.As same as color degredation,TOC degradation by O₃ oxidation and O₃/H₂O₂ oxidation of organics also fits the first order reaction kinetics model.?3?The degradation rate of organic matter improved with the increase of hydrogen peroxide dosage.However,when the dosage increased from4mL to 8mL,the degradation rate of both color and TOC slowed down.This proves that hydrogen peroxide needs to be dosed properly.Excess hydrogen peroxide,on the contrary,will compete with the organic material to consume the oxidant.?4?Using Gaussian09 and Material Studio7.0 to optimize the molecular structure of organic compounds and calculating their 21 kinds of quantum chemical structure descriptors.The correlation between degradation rate constants and molecular structure descriptors was analyzed.The results showed that:Fukui?-?_max?Fukui?+?_max?Fukui?0?_max?q?C-H?_max had strong correlation with the color degradation rate constant K_color8,among which Fukui?-?_max,Fukui?+?_max,Fukui?0?_max were negatively correlated with K_color8,and q?C-H?_max was positively correlated with K_color8.BO_max?q?C-H?_ave?qH_min had strong correlation with the TOC degradation rate constant K_TOC8,among which BO_max was negatively correlated with K_TOC8,and q?C-H?_ave,qH_min were positively correlated with K_TOC8.?5?The optimal model of color degradation kinetics and TOC degradation kinetics was established by stepwise multiple linear regression?MLR?in SPSS respectively:The optimal K_color8 model of color degradation was K_color8=36.641+0.536?+225.357 q?C-H?_ave-137.656 qH_max-235.093f?+?_max,the R²of model was 0.891,internal validation q ²=0.681,external validation Q²_ext=0.945.The optimal K_TOC8 model for TOC degradation was K_TOC8=1.608-0.624BO_max-1.701q?C-H?_max+0.117E_LUMO-0.061E_GAP,R²=0.684,internal verification q²=0.585,external verification Q²_ext=0.966.And after internal and external validation,t validation,Fisher validation and Y random verification confirmed the model stability and better prediction ability.After internal and external validation,t validation,Fisher validation and Y random validation,the models were confirmed to have stability and good predictive ability.?6?The 3D-QSAR model was constructed by SYBYL-X,and the effect of field on the chromatic degradation rate of organic matter was analyzed based on the 3D equipotent graph of organic matter.The results were as follows:Taking the Kcolor8 reaction kinetic constant of 16 kinds of organic compounds as the dependent variable and the molecular structure parameters of the organic compounds as the independent variables,12 groups of CoMSIA models were constructed and verified with stability and good predictability.The random selection model 7 was analyzed and discussed,whose R²=0.980,internal verification q²=0.598,external verification Q²_ext=0.781.The results of CoMSIA model show that the contribution of electrostatic field and hydrogen bond acceptor field to chroma degradation rate were relatively large.