Study On The Mechanism Of Catalytic Ozonation Of Refractory Organic Pollutants By Kaolinite

In recent years,water pollution has become an environmental issue that has attracted widespread attention all over the world,and the problems of wastewater treatment are highly concerned.With the development of industries such as chemicals,pharmaceuticals,pesticides,dyes and detergents,a large number of organic substances containing aromatic flow into water,causing serious water pollution.p-nitrophenol(abbreviated as p-NP)is used as an intermediate for chemicals such as pesticides,medicines,and dyes.The demand at home and abroad is increasing.The wastewater has complex components and serious damage to the environment.There is still a certain distance between the quality of the effluent and the discharge standards.Therefore,it is urgent to adopt a feasible deep treatment method to achieve the purpose of water purification.Catalytic Ozonation Process(COP)technology is considered as one of the most effective advanced treatment methods for refractory organic wastewater.The catalytic activity and cost of the ozone catalyst in this technology play a decisive role in engineering applications.In this study,the low-cost raw mineral catalyst kaolin and its calcinations were used to COP of p-NP simulated wastewater,achieving efficient and advanced treatment.The mechanism of kaolin and calcination modification kaolin in the COP of p-NP was further discussed.(1)The raw kaolin(rKL-1,rKL-2,and rKL-3)composed of different components was used to investigate the efficacy and mechanism of degradation of p-NP in the COP.Compared to the Single Ozonation Process(SOP)(56.74%),rKL-1-COP(93.44%),rKL-2-COP(96.50%)and rKL-3-COP(97.43%)can promotes COD removal in NPS.The removal mechanism involves direct oxidation of ozone,oxidation of ·OH.Together with the Si–O and Al–O groups,Mg oxides,Fe oxides,and surface hydroxyls form the complex catalytically active sites of rKL,and the active sites of Mg oxides,Fe oxides,together with Si–O and Al–O groups are more activity.(2)The calcined kaolin(cKL-1,cKL-2,cKL-3)was prepared to explore the efficiency and mechanism of p-NP degradation in COP system.cKL-1-COP(38.8%),cKL-2-COP(50.71%)and cKL-3-COP(74.31%)systems also promoted TOC removals of NPS.The removal mechanism of TOC in cKL-COP system involves ozone direct oxidation and non OH active species oxidation.The Si-O and Al-O groups in amorphous structure are their catalytic active centers.