本研究實驗結果顯示，提高製備溫度有助於提高比表面積與純度，並增加其光降解效率，以50℃為製備溫度效果最佳；延長製備反應時間，會使氧化鋅晶體粒徑變大，並有助於提高其純度與光降解效率。提高製備氧化鋅之酸鹼度會改變表面結構，同時亦提高其比表面積與晶體成晶狀況，有助於增加污染物的光降解速率。其中，以乙二醇為製備溶劑、氯化鋅為前趨物，在無水、溫度50℃、酸鹼度為12的狀態下反應48小時，可得純度最高、光催化效率最佳之奈米氧化鋅。然而氯化鋅等物質在二醇類或在含水二醇類溶劑中之產物形成機制，與光催化過程中污染物物種的變化情形等有待後續深入研究。;General photocatalyst included titanium dioxide (TiO2), zinc oxide (ZnO) and so on, and titanium dioxide has been main widely studied. However, in practical application, titanium dioxide is still subjected to limitations. Zinc oxide have the same nature with titanium dioxide, and zinc’s price is lower than titanium, therefore, zinc oxide is the one of the potential materials to replace titanium dioxide. Preparation of nano zinc oxide involves many methods, like vapor deposition, physical crushing method, sol-gel method, etc., but how to produce economically large-scale product is the key issue that must be overcome. Preparation of nano zinc oxide has very high cost in the majority of the synthesis report. This study selected glycol as a key solvent, using its characteristic that can generate intermolecular hydrogen bonds controlling the formation of small aggregates. This study used a simple, low-cost experimental procedure to prepare the nano zinc oxide, and also discussed the factors such as solvents, precursor species, hydration, temperature, pH, reaction time, etc., which influenced physical and chemical properties of zinc oxide. The reaction conditions to obtain the highest photocatalytic efficiency are also investigated.
The results showed that as the temperature increased surface area, the purity of zinc oxide and its efficiency of the photodegradation also increased. Thus, it is concluded that 50 ℃ is the optimal temperature. Extending reaction time, the zinc oxide will grain larger size, helping to improve its purity and the efficiency of the photodegradation. Higher pH will not only change the surface structure, but also improve its surface area and crystal growth, helping to increase the rate of photodegradation of pollutants. Among them, ethylene glycol as the solvent, zinc chloride as the predecessor, the absence of water, 50 ℃, pH=12 and 48 hours are the optimal conditions to obtain the nano zinc oxide with highest purity, and inhanced efficiency of the photodegradation.