Synthesis Of ZnO With Different Morphologies And Research Of Its Photocatalytic Degradation Performance

Zinc Oxide (ZnO) is a new function semiconductor, which is a kind of important materials with advantanges of high efficiency, nontoxicity and low price, has wide application prospects in photology, sterilization, environmental protection and so on.This thesis summarizes the development of semiconductor matericals, basic properties, main chemical synthesis methods, photocatalytic degradation performance and mechanism of ZnO. ZnO with different morphologies was synthesized by hydrothermal method using sodium carboxymethylcellulose (CMC) and sodium alginate (SA) as crystal growth modifiers by changing dosage of the modifier. Furthermore, as-synthesized ZnO was applied in photocatalytic degradation of organic pollutant phenol. ZnO was characterized and analyzed by XRD, SEM, UV-Vis and HPLC. The main research contents are as follows:(1) ZnO sythesized in 50:3 molar ratio of zinc acetate and CMC. The influences of reaction temperture and time on the morphologies of ZnO were invesitigated. The characterization results revealed that as-synthesized ZnO with fine crystallinity, different morphologies such as cauliflower top, dumbbell-like and umbrella-like. Optimized reaction conditions was at 120 ℃ for 12 h via hydrothermal mehtod. ZnO sythesized at optimized reaction conditions as the photocatalyst was applied in the degradation of phenol solution, the result showed that the photocatalytic performance of the concentration of 1.0g/L ZnO was fine.(2) ZnO were hydrothermally sythesized at 120℃ for 12 h, aided by different dosage of CMC and SA. The result showed that with the increase dosage of the crystal growth modifider, the morphologies of ZnO synthesized via CMC as a modifider changed from rods into uniformly cauliflower-like, but morphologies of ZnO synthesized via SA changed from messy rods into spheres. All these as-synthesiezd ZnO were applied in the photocatalytic degradation of phenol solution, ZnO synthesized via CMC showed much better photocatalytic performance than ZnO synthesized via SA.(3) Using ZnO sythesized at 120℃ for 12 h, with molar ratio of zinc acetate and CMC is 50:9 as the photocatalyst, effects of the concentration of ZnO and initial concentration of phenol solution on photocatalytic degradation of phenol were invesitigated. The result showed the concentration of 1.0g/L ZnO had the best photocatalytic degradation performance in 30 mg/L initial phenol solution. The degradation intermediates of phenol were investigated via HPLC and the reaction mechanism of photocatalytic degradation phenol was presumed. The result showed that the degradation intermediates of phenol were hydroquinone, benzoquinone, catechol, maleic acid and so on. Along with the increase of degradation time, the aromatic intermediates were decomposed into open ring compounds.