以奈米結構氧化鋅對濾材表面處理之研究

Abstract

奈米氧化鋅為一光觸媒且在材料領域上已發展出許多製備技術，而本研究利用已發展成熟之化學氣相沉積法和溶膠凝膠法於濾材上製備不同型態之奈米氧化鋅結構，分別探討氮氣流量、氧氣流量、成長溫度以及燒結時間、燒結溫度、鍍液濃度對於奈米氧化鋅結構的影響。此外，利用經過表面處理後之濾材以紫外光/氧化鋅程序處理氣相丙酮以及大腸桿菌，並評估其最佳之操作條件以及處理效率探討。 根據實驗結果，以化學氣相沉積法在氮氧比6：1、成長溫度在600℃時能產生較理想的六角柱狀氧化鋅，而氮氧比3：1、成長溫度為800℃時能製備出四腳針狀氧化鋅。利用溶膠凝膠法則以濃度0.45M的鍍液配合700℃的燒結溫度和1小時的燒結時間下可製備出圓球形氧化鋅結構，兩者處理丙酮效率以越低濃度、低流速下的處理效率越高，而因圓球形氧化鋅比表面積大於六角柱狀氧化鋅，故整體效率以圓球形氧化鋅高於六角柱狀氧化鋅。大腸桿菌殺菌實驗中，兩者均以越低流速下的處理效率越高，因六角柱狀氧化鋅經激發後產生的電子電洞對多於圓球形氧化鋅，故整體殺菌效率則以六角柱狀氧化鋅優於圓球形氧化鋅。

Nano ZnO is one of common used photocatalyst so that there are many manufacturing methods developed in material science and industrial field. In this study, chemical vapor deposition and sol-gel methods were applied to produce different types of nano structure of ZnO to investigate the effect of different factors with the structure characteristics of ZnO, such as growth temperature, flow rate of carrier gas, flow rate of oxygen gas, sintering temperature, concentration of coating solution and sintering time. These surface treatment techniques were applied on stainless steel meshes to manufacture photocatalyst gas filters coated with nano structure of ZnO. A series of UV/ZnO experiments applying these photocatalyst gas filters were executed to evaluate the decomposing capability to acetone and disinfection ability to E. coli. The influence of operating factors on the treatment efficiencies and the optimum operating parameters were also investigated. According to the results of chemical vapor deposition method in this study, the hexagonal-shaped ZnO crystal will form under the condition of N2/O2 ratio 6：1, growth temperature 600℃, and whiskers will form under the N2/O2 ratio 3：1, growth temperature 800℃. By sol-gel method, circular-shaped ZnO can be grown under the initial Zinc Acetate dihydrate concentration 0.45 M, sintering temperature 700℃, sintering time one hour. The photocatalyst decomposition efficiency of acetone was elevated with lower flow rate and lower initial concentration of acetone by both these two kinds of nano structure of ZnO. The higher BET surface area of circular-shaped ZnO than that of hexagonal-shaped ZnO can be explained to higher overall efficiency of circular-shaped ZnO.Results in disinfection effects to E.coli showed that lower flow rate can obtain more ascended efficiency for both type of ZnO. But disinfection efficiency of hexagonal-shaped ZnO is better than circular-shaped ZnO because of more electron-hole pairs formed from hexagonal-shaped ZnO than circular-shaped ZnO.