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Titanium dioxide （TiO2） has been extensively studied through the world andconsidered as reference photocatalyst in the degradation of organic pollutants,sewage treatment, air purification, disinfection due to its superior photocatalyticperformance, nonselective degradation of various organics, deep mineralization rate,low cost, inert and non-toxic properties.However, the pure TiO2with energy band gap of3.2eV exhibits spectralresponse only in UV region, which limits the practical applications due to the poorutilization of solar lights. At the same time, due to the higher recombination rate ofphotocarrier and low quantum efficiency, the photocatalytic efficiency of TiO2wasalso influenced. Therefore, considerable effort has been made to increase theabsorption of TiO2in the visible region to improve its visible light response throughvarious surface modifications such as doping of various metal or nonmetal oxides.In this paper, N,F-codoped TiO2film, La,N,F-codoped TiO2film,Fe,N,F-codoped TiO2film and Co,N,F-codoped TiO2film photocatalysts withsol-gel method at room temperature were proposed. A series of photocatalyticdegradation experiments were carried out under visible light irradiation in thepresence of doped TiO2films, which using acid red B and Methylene blue trihydrateas model compounds. Also, some influence factors like heat-treatment temperatureand number of film on the photocatalytic activities of the prepared TiO2photocatalysts, and irradiation time, light power, initial concentration, and solutionpH on the photocatalytic degradation of acid red B and Methylene blue trihydratewere assessed in detail by UV–vis spectra and ion chromatography.Theexperimental results proved that, to begin with, the photocatalytic activity ofN,F-TiO2film is better than that of N-TiO2film or F-TiO2film. Degradation rate of10mg/L acid red B is up to98.5%in the presence of N,F-TiO2film for30hourirradiation under the visible light. Secondly, the photocatalytic activity ofLa,N,F-TiO2film is better than that of N,F-TiO2film. Degradation rate of10mg/L acid red B is up to100%in the presence of La,N,F-TiO2film for30hour irradiationunder the visible light. Lastly, the photocatalytic activity of Fe,N,F-TiO2film isbetter than that of Co,N,F-TiO2film. Degradation rate of10mg/L Methylene bluetrihydrate is up to100%and98.6%which respectively in the presence ofFe,N,F-TiO2film and Co,N,F-TiO2film for12hour irradiation under the visiblelight.
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