The Synthesis Of Nanometer Zinc Oxide By Anodic Oxidation And Research On Photocatalytic Degradation Of Phenol

Now the environmental problems are increasingly severe, so the treatment ofwastewater has got more and more attention, especially the degradation ofphenol pollutants. Today, the photocatalytic degradation reaction has been moreand more popular. And the metal oxide semiconductors are the commoncatalysts. Zinc oxide, as the new wide band gap semiconductor, was graduallyconcerned due to its high absorption ability to UV light, high content of surfacehydroxyl, morphology diversification. The photocatalytic reaction mechanism ofZnO is similar to TiO2, which was expected to replace TiO2.In this experiment, nanometer zinc oxide was prepared by electrochemicalanodic oxidation in the electrolyte, which containing ammonium chloride,ethanol, distilled water. The prepared flake nanometer ZnO had a lot of exposedpolar surface, and was used to degrade the phenol solution. The main researchcontents and conclusions are as follows:1. Compare the products prepared in different types of electrolytic solutions, different types of alcohol, different electrolytes, the morphology of sample,which was prepared in the electrolytic solution containing ammonium chloride,ethanol, distilled water, was the best from the SEM picture. Next, the orthogonalexperiments were taken by change the reaction parameters. The flake nanometerZnO, prepared under the condition: the voltage is7V, the oxidation time is25minute, the mass fraction of NH4Cl is1.2%, the volume of hydrogen peroxide is0.4ml, show uniform structure, surface cleaning, no reunion in its SEM picture.2. From the XRD, FT-IR, BET characterization, the unburned nanometerzinc oxide has a large number of hydroxyl radical, a small amount of chlorineion, a very strong O－C=O,－OH infrared absorption peak, and a largerspecific surface area. The zinc oxide after roasted at325℃for4hour, the XRDpeak with less disturbance become more sharp, and the peak width at half heightis more narrow, except the O－C=O,－OH infrared absorption peak becomeweaker. That is to say the nanometer zinc oxide after roasted has more highcrystallinity and purity.3. By comparing the efficiency of photocatalytic degradation of phenolsolution by adding different nanometer zinc oxide, the flake nanometer zincoxide before roasting has the highest degradation efficiency on phenol. Thedegradation mainly occurred in the first60minute, and the catalytic rate wasgradually decreased. After120minute, the degradation efficiency of phenol was73.36%. In the photo catalytic reaction process, the degradation efficiency ofphenol has greatly improved after the exposure of oxygen. 4. Nanometer flake zinc oxide was characterized by photoluminescence andRaman spectroscopic. The UV emission peak of nanometer zinc oxide fromphotoluminescence spectra moved to the visible region and became more widthand stronger. Raman spectroscopy has also undergone a red shift. All these showthat nanometer flake zinc oxide contain many defects, such as oxygen vacancies,which make the nanometer flake zinc oxide exhibited a higher photocatalyticactivity.