Co-FeOOH Catalytic Ozone Oxidation Of Trace Organic Pollutants In Water

With the development of the chemical industry and the improvement of people's living standard,the pollution of water environment tends to be diversified and trace organic pollutants have been frequently detected in the aquatic environment.Because of the unsatisfactory removal of trace organic pollutants in conventional treatment plant,the researchers have been devoted to the study of efficient water treatment technology to improve the removal efficiency of trace organic matter in water.In this paper,the Co-FeOOH catalyst was synthesized by alkali precipitation method and the physical structure and surface properties of Co-FeOOH were characterized by Fourier transform infrared spectroscopy?FTIR?,X-ray diffraction analysis?XRD?,scanning electron microscope?SEM?,X-ray photoelectron spectroscopy?XPS?,specific surface analysis?BET?method.The Co-FeOOH was applied in the catalytic oxidation of trace organic pollutants.The preparation conditions of Co-FeOOH were studied in this paper.The best preparation conditions of Co-FeOOH were that the Co/Fe,activation time and activation temperature were respectively 0.13,48h and 60?.The characterization results indicated that the synthesized Co-FeOOH was of nanorods structure.The surface of Co-FeOOH had abundant surface hydroxyl groups.The BET surface area,pore volume and pore diameter were 139.332 m²/g?0.236 cm³/g?8.291 nm,respectively.In addition,the pH_pzc of Co-FeOOH was 7.82,and the oxygen element on the surface of Co-FeOOH mainly belongs to chemisorbed state.Nitrobenzene?NB?and atenolol?ATL?ware selected as the target compounds,the catalytic performance of Co-FeOOH for the ozonation of NB and ATL were investigated.The effects of different influencing factors on the removal efficiency of nitrobenzene were investigated.Results showed that the presence of Co-FeOOH significantly improved the removal efficiency of NB and ATL.In the Co-FeOOH catalytic ozonation of NB,the removal efficiency of NB gradually increased with the increase of the concentration of ozone and the amount of catalyst.NB has the highest removal efficiency when the initial concentration of NB is 100?g/L.The presence of HCO₃^-could significantly inhibit the removal of NB,and the inhibitory effect was enhanced with the increase of HCO₃^-concentration.In the Co-FeOOH catalytic ozonation of NB,the removal efficiency of ATL was positively correlated with the concentration of ozone and the amount of catalyst.ATL has the highest removal efficiency when the initial concentration of ATL is200?g/L.In addition,HCO₃^-promotes the removal of ATL,which may be due to the large amount of CO₃·^-in aqueous solution.The mechanism of the Co-FeOOH catalytic ozonation of NB was discussed.The results of the pH value on the removal of NB showed that,the removal efficiency of NB was the highest in sole-ozonation and catalytic ozonation process when the pH value was 9.The addition of tert-butyl alcohol significantly reduced the removal of nitrobenzene,which indicating that hydroxyl radicals played a leading role in the removal of NB.In addition,the ESR and FD test results indicated that the presence of Co-FeOOH significantly enhanced the generation of hydroxyl radicals compared with sole ozonation.Based on the above analysis,the process of Co-FeOOH catalytic ozonation of NB was consistent with the reaction mechanism of hydroxyl radical.The mechanism of the Co-FeOOH catalytic ozonation of ATL was discussed.The results of the pH value on the removal of NB showed that,the removal efficiency of ATL was the highest in sole-ozonation and catalytic ozonation process under alkaline conditions.When the pH value of aqueous solution was 3.82,Co-FeOOH showed high catalytic activity,and the removal efficiency of ATL isignificantly increased by 26.11%compared to sole-ozonation.But Co-FeOOH did not appear very high catalytic activity under neutral and alkaline conditions,which may be due to that the removal efficiency of ATL is close to 100%in sole ozonation process under neutral and alkaline conditions.The addition of tert-butyl alcohol had certain inhibitory effect on the removal of ATL,but the inhibitory effect was very weak.The result indirectly proved that hydroxyl radicals were not the primary role in the degradation of ATL.The intermediate products of ATL were identified by UPLC/MS/MS.The degradation pathways of ATL were subsequently proposed.The results showed that the major pathways of degradation of ATL included hydroxylation,aromatic ring opening,oxidation and cleavage of side chain.Co-FeOOH has a high stability during the catalytic oaonation process.The catalytic performance maintained a good stability after several times of recycled use and the metal ion leaching was apparently negligible during catalytic ozonation.