Preparation Of Pr-N Co-doped TiO₂Immobilized On Nickel Foam Substrates And Its Photocatalytic Property

Nano TiO₂-based semieonduetor photocatalysis technology has been a a research hotspotbecause it can mineralize organic Pollutants into CO2and H2O, using lights as energy sources.However, TiO₂has its own shortcomings limits the application in wastewater treatments,since The band gap energy of TiO₂corresponds to the wavelength of UV light <387nm,which means much of the natural light could not be used，also the lifetime of carriers in thephotoconductor is short. This is an obstacle to the way of degrading pollutants using TiO₂as aphotocatalyst. Modification of TiO₂to enhance the visible light sensibility to achieve theindustrialization has been the subject of recent research.Pr-N co-doped TiO₂photocatalyst was prepared by a sol-gel method with tetrabutyltitanate as Ti source, Pr （NO₃）₃as Pr source, and urea as N source, which was immobilized onnickel foam substrates. The photocatalyst was characterized by X-ray diffraction （XRD）,UV-Vis diffuse reflectance spectroscopy （DRS） and scanning electron microscope （SEM）. Itshows that the doping of Pr and N lead to an enhancement of the absorption in the visiblelight region. Compared to pure TiO₂, Pr-N co-doped TiO₂photocatalyst has a betterphotocatalytic property. The crystallite size of co-doped TiO₂was11.89nm, which was muchsmaller than that of pure TiO₂, the doping of Pr and N could hinder the increase of thecrystallite size.the degradation of malachite green was investigated as a model reaction, the removal ofmalachite green with Pr-N co-doped TiO₂was2.6times of pure TiO₂. An orthogonalexperiment was designed, the result shows result shows that the optimal parameters ofphotocatalyst are n（Pr）:n（N）:n（Ti）=0.0020:0.2:1, calcined at400℃, and the factor that thedoping of Pr was more important than the doping of N and calcinated temperature.Malachite green oxidation degradation was kinetically investigated byphotoelectrocatalytic in photoelectrocatalytic reactor, using Pr_0.002N_0.2/TiO₂photocatalyst aselectrode. The result shows that the initial concentration, pH, voltage and temperature had asignificant impact on the oxidation rate. The kinetic equation for malachite green oxidationunder the conditions of10³0mg·L-1of initial concentration,3⁸of pH,1⁵V of voltage, 298³38K of temperature could be described using first order kinetics, which was fitted wellwith the experimental date. The lower activation energy of11.99kJ·mol-1shows the reactioncan be initiated easily; The reaction order of pH （1.6347） is higher than that of voltage（0.8502） and initial concentration （0.1238）, which indicates that the oxidation rate can becontrolled efficiently through adjusted pH.