Frabrication Of N Doped TiO₂ Nanotube Arrays And Photocatalytic, Photoelectrocatalytic Degradation Of Hexachlorobenzen Using Visible Light

Different nitrogen doped Titanium dioxide (TiO₂) nanotube arrays were preformed by electrochemical anodization and wet chemical method by using ammonia, Ethylenediamine, Butylamine as nitrogen source respectively. The samples were characterized by scanning electron microscope (SEM), X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The relationship between Nitrogen doping behavior and visible light photocatalytic property was studied by the experiment of degradation of Hexachlorobenzen (HCB) wastewater. The result indicated that highly ordered TiO₂ nanotube arrays were growth on titanium substrates, the length of the tube was approximately 500 nm and the diameter was about 100 nm. The doping of N hindered the growth of crystalline particles and prevented the crystal of TiO₂ transferred from anatase to rutile. The photocatalytic experiments indicated that Inorganic nitrogen was more conducive to let nitrogen access to TiO₂ lattice and substitute nitrogen had higher visible light photocatalytic activity than interstitial nitrogen.We used HCB as targeted pollutants to studied N doped TiO₂ photocatalytic properties. We discussed the photocatalytic factors as the species of Nitrogen, the amount of Nitrogen, calculated temperature, pH of the solution and the concentration of HCB, also investigated the stability of N doped TiO₂. The result shew that 2 mol/L ammonia as N source under the condition of 450℃calcination temperature displayed the best photocatalytic properties, pH had influence on the degradation of HCB, the degradation efficiency was the best on neutral condition. N doped TiO₂ has a good cycling performance, when using 6 times, it still expressed good visible light photocatalytic properties.The best photocatalytic N doped TiO₂ nanotubes was used as the working electrode, Pt electrode as auxiliary electrode, saturated calomel electrode as reference electrode to photoelectrocatalytic degradation of HCB pesticide wastewater. The factors as anode bias voltage, electrolyte type, electrolyte concentration, pH performance were disscussed. The experiment demonstrated that selecting Na₂SO₄ as electrolyte expressed better photoelectrocatalytic propercity than the photocatalytic effect, the voltage was 1 V, 0.2 mol/L Na₂SO₄ as electrolyte and pH was 5 expressed the best photoelectrocatalytic properties.At last photocatalytic and photoelectrocatalytic degradation mechanism of HCB under the conditions of visible light were analyzed. The Mass Spectrometry analysis result shew that after photoelectrocatalytic or photocatalytic degradation, in addition to compounds of Chlorobenzene series, there are benzoic acid, dibutyl phthalate, dimethyl phthalate, phthalic ester, alcohols and acids in the degradation products which indicated that the photocatalytic and the photoelectrocatalytic dechlorination process was not only a simple dechlorination process, but also a series of reaction of Hydroxyl radicals in the water, thus completely transformed Poisonous and refractory organics into CO₂ and H₂O...