Study On Photocatalytic Reduction Of Nitrate In Water Over TiO₂

Nitrate pollution of groundwater has become one of the urgent problems for the countriesof the world is facing many problems, using conventional technology to remove nitrate isfacing many problems, research and development of new technologies, new methods toremove nitrate to become the subject of widespread concern. This paper the method of TiO₂photocatalytic removal of nitrate, systematically investigated the effect of pure TiO₂on theremoval of nitrate nitrogen, innovative studyed of the effectiveness of N-doped TiO₂photocatalytic reduction of nitrate nitrogen，designed to open up a new and follow the road forthe removal of nitrate nitrogen.TiO₂as a catalyst for photocatalytic reduction of nitrate，the effects of a hole scavenger,nitrate nitrogen concentration, the amount of catalyst, the protective gas, light source, lightintensity and water ions and other factors. Exploring the reaction mechanism, at the same time,useing ultrasonic, of TiO₂doped with Fe³⁺and other methods to strengthen. The resultsshowed that: TiO₂as a photocatalyst, compared with methanol, sodium formate and EDTA,formic acid is a good hole scavenger, formic acid concentration of50mmol/L, when therestore is better. Nitrate concentration, amount of catalyst, to protect the gas N2, light sourcesand light intensity on the TiO₂photocatalytic reduction of nitrate reaction has a greater impact.TiO₂photocatalytic reduction activity of different types of nitrate in water, the activity orderof highest to lowest: FeNO₃> KNO₃NaNO₃, the water of Ca²⁺, Mg²⁺is basically the sameand has little effect, the water of Cl^-, PO43-so that the catalytic activity declined slightly,SO₄^2-complete inhibition of the catalytic reduction reaction of nitrate light. The activity andselectivity of photocatalytic reduction of nitrate were raised with ultrasonic and Fe³⁺, fe-dopedTiO₂enhanced the activity of TiO₂, but the selective variation. The nitrate removal rate of35.16%, when TiO₂of Photocatalytic reduction of nitrate activity. Nitrate photocatalyticreduction reaction in line with the first-order kinetics, parallel-sequential step-by-stepreaction.TiO₂catalyst was prepared using titanium sulphate as the precursor by a hydrothermalprecipitation method. The catalyst was characterized by scanning electron microscopy （SEM）,energy dispersive x-ray spectrometer （EDS）, X-ray diffraction （XRD）, fourier transform infraredspectroscopy （FTIR）, and X-ray photoelectron spectroscopy （XPS）. The paper studies theimpact of N-doped TiO₂preparation methods on photo catalytic performance, the main test oftitanium sulfate, ammonia concentration, dropping ammonia water speed, pH, calcinationstemperature, hydrolysis temperature, feeding methods, the influences of the photo catalystactivity, esearch N-doped TiO₂photo catalyst to restore the effectiveness of nitrate in thewater. The results were shown that when two reactant concentration were up to0.5mol L^-1,pH9.0, calcination temperature400°C, and hydrolysis under the conditions of temperature100℃, along the feeding Preparation of N-doped TiO₂photocatalysis has better activity. photocatalytic reduction of nitrate nitrogen concentration of50mg/L aqueous solution ofnitrate, the reaction120min, nitrate conversion rate of95.8%. The catalyst without dopedmetal components, there is no heavy metal components leaching risk, a new type ofphotocatalytic reduction of nitrate catalyst.