| With the development of industry and the change of people's life style,more and more emerging organic pollutants that are difficult to degrade are discharged into the water environment,which poses a very serious threat to the ecological environment and human health.Advanced oxidation technology is one of the most effective methods to degrade organic pollutants,because it can produce hydroxyl radicals with strong oxidation ability,so as to achieve the degradation and mineralization of organic pollutants.As one of the advanced oxidation technologies,Ti O2-based photocatalytic technology has been widely studied due to the advantages of stable catalyst properties,mild reaction conditions,low cost and environmentally friendly.However,Ti O2 can only be excited by UV light and carriers are easy to recombine,resulting in the low photocatalytic efficiency.In order to improve the degradation efficiency of pollutants by the photocatalysis,photocatalytic technology can be combined with other advanced oxidation technology,such as Fenton oxidation technology,PMS activation technology and membrane separation technology.Through the synergistic effect,the catalyst can enhance the utilization of light,promote the separation of photogenerated carriers,decomposition of H2O2 and activation of PMS.In the collaborative advanced oxidation process of these Ti O2-based photocatalysts,the optimization of reaction conditions,catalyst cycle stability and significantly improved degradation efficiency are all the key issues should be solved.Therefore,focusing on the collaboration between Ti O2-based photocatalysis and other technologies,we mainly conduct the in-depth research from the following three parts:1)Fe2O3/Ti O2/r GO(FTG)ternary composite photocatalyst was prepared by a simple one-step solvothermal method.Fe2O3 and Ti O2 strongly interacted with each other and distributed uniformly on r GO,which suppressed the agglomeration of nanoparticles.The size of Ti O2 crystal was about 8-10 nm.The interaction between Fe2O3 and r GO and Ti O2 enhanced the absorption of visible light by Ti O2 and improved the carrier migration efficiency.The conductivity of r GO promoted the reduction of photogenerated electrons to Fe3+,which is conducive to driven Fenton reaction.FTG showed a stable catalytic activity in the p H range of 3-9,and almost no Fe ions were dissolved during the reaction process,thus the catalyst had a high cycle life.In the FTG/H2O2/light system,·OHads and·O2-were the main reactive oxygen species acting on MO degradation.2)Fe2O3/C-Ti O2(Fe/C-Ti O2)composite photocatalyst was prepared by the solvothermal method,which realized the in-situ carbon doping and Fe2O3 modification.Carbon doping and Fe2O3 modification increased the specific surface area of Ti O2(176m2/g),and carbon doping further enhanced the stability of Fe/C-Ti O2 structure,reduced Fe ions leaching,and was conducive to the activation of PMS.Fe2O3 modification enhanced the visible light absorption of Ti O2,which was beneficial to the separation efficiency of photogenerated charge and improved the photocatalytic performance.The results showed that the optimal dosage of PMS was 0.65 m M,and Fe/C-Ti O2 exhibited high and stable catalytic activity in the p H range of 3-9.The degradation efficiency of4-CP was improved by the coordination of PMS activation with Fe/C-Ti O2 under the visible light irradiation.The main active species were·O2-and 1O2,which were different from the traditional·SO4-and·OH.3)The Ti O2/r GO(TG)composite photocatalyst prepared by solvothermal method was anchored to carbon nanotube-polyethersulfone(CNT-PES)membrane by vacuum assisted deposition,and then the TG/CNT composite photocatalytic membrane was obtained.Graphene doping increased the contact area between Ti O2 photocatalyst and carbon nanotubes,which was conducive to the transfer of photogenerated electrons on the surface of Ti O2.The existence of oxygen vacancies on TG further facilitated the capture of electrons,improved the separation efficiency of photogenerated carriers on Ti O2,and improved the photocatalytic activity of TG for tetracycline hydrochloric acid(TCH).And h+and·OH were the main active species for TCH degradation.The prepared TG/CNT composite membrane showed high water flux and could maintain high permeability and selectivity.In the process of TCH separation and removal by the photocatalytic membrane,the TCH removal rate and water flux could still be maintained during multiple cycles,indicating that TG/CNT composite membrane had excellent antifouling performance and self-cleaning ability. |
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