Degradation Of Aniline By Persulfate Activated With HCO₃^-/SO₃^2-/Mⁿ⁺

Aniline organic wastewater has attracted wide attention due to its large discharge,difficult biodegradation and high toxicity.Persulfate advanced oxidation processes（AOPs）by activating persulfate（PDS）to produce highly reactive oxygen species（ROS）to degrade organic pollutants,with high efficiency,fast speed,thorough reaction and mild reaction conditions,of which anion activating PDS degradation of organic pollutants has advantages of low cost,simple operation and non-toxic environmental and highlights a broad application prospects in the organic wastewater treatment.This paper takes aniline as the research object to simulate organic wastewater,studies the degradation process of aniline in HCO₃^-/PDS、HCO₃^-/Cu²⁺/PDS、SO₃^2-/PDS and SO₃^2-/Fe²⁺/PDS systems,investigates the degradation kinetics and influencing factors of aniline in each system,detects reactive oxygen species in degradation systems,and explores the degradation mechanism and path of aniline.The main results are as follows:1.In the HCO₃^-/PDS system,the degradation process of aniline followed the first-order kinetic equation.Under the conditions of 50 m M HCO₃^-and 10 m M PDS,the degradation rate of 10 mg/L aniline in 240 min was 94.83%,the reaction rate constant k was 0.0110 min^-1,and the TOC removal rate was 44.32%.Cl^-,HPO₄^2-,NO₃^-,SO₄^2-,Mn²⁺and Zn²⁺had no effect on the degradation of aniline;Cu²⁺accelerated the degradation of aniline,and the degradation rate of aniline within 180min is 96.98%;Fe²⁺had a slight inhibitory effect on the degradation of aniline.Combined with free radical quenching experiment,EPR spectrum and literature analysis,it was confirmed that the main ROS in this system were ¹O₂and HCO₄^-.The intermediate products of aniline degradation were obtained by GC-MS as p-diphenol and p-benzoquinone,and the degradation mechanism and possible pathways of aniline were deduced.2.In the HCO₃^-/Cu²⁺/PDS system,the degradation process of aniline followed the first-order kinetic equation.Under the conditions of 6 m M HCO₃^-,0.2 m M Cu²⁺,and 20 m M PDS,the degradation rate of 10 mg/L aniline within 90 min was 98.53%,the k was 0.0260 min^-1,and the TOC removal rate was 32.49%.Cl^-,HPO₄^2-,NO₃^-,SO₄^2-,Ca²⁺,Fe³⁺,Mg²⁺and Mn²⁺had no significant effect on the degradation of aniline.Combined with free radical quenching experiments,EPR spectra and comparative analysis of literature,it was confirmed that the main ROS in this system were·OH and ¹O₂.UV-vis spectroscopy confirmed the existence of HCO₃^--Cu²⁺complex.Five intermediates of aniline degradation were obtained by GC-MS,namely p-benzoquinone,nitrobenzene,p-fluorol,azobenzene and p-hydroxydiphenylamine,and the degradation mechanism and path of aniline were deduced.3.In the SO₃^2-/PDS system,under the conditions of 10 m M SO₃^2-and 10 m M PDS,the degradation rate of 10 mg/L aniline within 180 minutes was 58.70%,and the TOC removal rate was 39.38%.HCO₃^-,HPO₄^2-,Cu²⁺and Fe²⁺could promote the degradation of aniline and the degradation rate of aniline was increased by 14.48%,7.13%,7.86%and 35.85%,respectively.Cl^-,NO₃^-,SO₄^2-and Zn²⁺had no significant effect on the degradation of aniline,and Mn²⁺inhibited the degradation of aniline which degradation rate decreased by 40.43%.Combined with free radical quenching experiments,EPR spectra and comparative analysis of literature,it was confirmed that the main ROS in the system was·OH.Four intermediates of aniline degradation were obtained by GC-MS,namely nitrophenyl 2-aminobenzenesulfonate,3,7-dimethyl-1-octanol,lauric acid and 3,5-di-tert-butylphenol,and the degradation mechanism and path of aniline were deduced.4.In the SO₃^2-/Fe²⁺/PDS system,the degradation process of aniline followed the first-order kinetic equation.Under the conditions of 10 m M SO₃^2-,1 m M Fe²⁺,and20 m M PDS,the degradation rate of 10 mg/L aniline within 60 min was 95.56%,k was 0.0359 min^-1,and the TOC removal rate was 34.17%.Mn²⁺had no effect on the degradation of aniline.HCO₃^-,HPO₄^2-,Cl^-,NO₃^-,SO₄^2-,Ca²⁺,Fe³⁺and Mg²⁺had inhibitory effects on the degradation of aniline.Combined with free radical quenching experiments,EPR spectra and comparative analysis of literature,it was confirmed that the main ROS in this system were·OH and ¹O₂.Six intermediate products of aniline degradation were obtained by GC-MS,namely p-benzoquinone,nitrobenzene,p-diphenol,azobenzene,p-hydroxydiphenylamine and 4-nitroazobenzene,and the degradation mechanism and path of aniline were deduced.In summary,HCO₃^-and SO₃^2-could activate PDS to degrade aniline,and the addition of Cu²⁺and Fe²⁺greatly improved the ability of the two systems to degrade and mineralize aniline.After the addition of Cu²⁺,the degradation time of aniline was reduced by 1.7 times,the amount of HCO₃^-was reduced by 7.3 times,and the ROS concentration was significantly increased;after the addition of Fe²⁺,the degradation time of aniline was reduced by 120 min,and the type and concentration of ROS were significantly increased.The above results indicated HCO₃^-/PDS、HCO₃^-/Cu²⁺/PDS、SO₃^2-/PDS and SO₃^2-/Fe²⁺/PDS systems could effectively treat aniline organic wastewater.