光觸媒是一種利用光照射後可以產生自由基，以自由基攻擊目標 污染物，再利用氧化還原方式達到降解污染物的催化劑。本研究主要探討利用不同多醣體製備的氧化鋅和市售觸媒，在不同的光催化條件下催化降解甲烯藍、結晶紫、剛果紅三種污染物，並進行其光催化效率比較。 天然多醣體製備之氧化鋅係利用不同天然多醣體：海藻膠、幾丁 聚醣、玉米澱粉所製備而成，經由光催化效率比較可以得知天然多醣體製備之氧化鋅和其：（a）配比高低無關，其中以3%-3%為最佳；（b）氧化鋅鍛燒溫度以450℃為最佳；（c）不同添加物，會產生不同的影響；（d）不同的多醣體，其光催化效果以海藻膠及玉米澱粉最好。對於光催化條件的選擇則循環水溫度以30℃最佳，而污染物初始濃度越低，光催化效果也越佳；觸媒劑量和酸鹼度有其最適值，實驗結果亦顯示光催化能力隨照射時間增長而下降。 Photocatalysts are kind of catalyst that can be irradiated by light and generate free radicals, and this kind of radicals will attack target pollutants using redox method for degradation of pollutants. This study investigated the preparation of zinc oxide catalyst in different conditions using different polysaccharide and its efficiency of photocatalytic degradation of three kinds of pollutants such as methylene blue, crystal violet, and congo red. Zinc oxide was prepared using different natural polysaccharides such as alginate, chitosan, and corn starch. Comparison of the photocatalytic efficiency of zinc oxide prepared using natural polysaccharides indicated that: (a) preparation was independent of ratio of composition; (b) 450 ℃ was the best calcination temperature of zinc oxide; (c) different additives will generate different effects among different polysaccharides used to prepared zinc oxide ; (d) the best photocatalytic efficiency was obtained for sodium alginate and corn starch with conditions for the photocatalytic circulating water temperature was 30 ℃,when the concentration of pollutants is low, the better photocatalytic effect was obtained. The experimental results showed that photocatalytic activity decrease on exposure time, catalyst’s dosage and pH.
