- 學位論文
光催化過硫酸鹽降解地下水中五氯酚之研究
Using Ultraviolet Light to Catalyze Persulfate for Degradation of Pentachlorophenol in Groundwater
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摘要
本研究利用254 nm紫外光催化過硫酸鹽(Persulfate, PS)反應生成硫酸根自由基（SO4-‧）與氫氧自由基（HO‧）氧化地下水中五氯酚鈉（Sodium Pentachlorophenol, PCP-Na）。實驗以不同紫外光強度及照光時間等條件，探討地下水中不同濃度五氯酚鈉的降解效率，五氯酚鈉濃度分別為150 mg/L、 300 mg/L、450 mg/L和600 mg/L，紫外光強度設定為80 μW/cm2、470 μW/cm2 和2260 μW/cm2，過硫酸鹽濃度為4.2 mM，照光時間為0.5至24小時。五氯酚鈉水樣與過硫酸鹽水樣體積比為40 mL：1 mL。首先，以無照光和照光方式對地下水中五氯酚鈉降解效率進行比較，得知，無紫外光催化下，過硫酸鹽氧化地下水中五氯酚鈉效果不佳，降解率僅10%以下，而在紫外光催化下，地下水中五氯酚鈉能被快速降解，降解率約可提升80%以上。 故後續實驗利用紫外光催化過硫酸鹽探討地下水中五氯酚鈉降解效率，實驗結果發現，紫外光強度在80 μW/cm2和470 μW/cm2時，照光時間0.5至24小時，PS氧化地下水中五氯酚鈉的效果不佳，降解率僅約10%。經紫外光強度2260 μW/cm2催化過硫酸鹽氧化地下水中五氯酚鈉，照光時間0.5小時，地下水中五氯酚鈉降解率約可達14%，而經照光時間12小時，地下水中五氯酚鈉降解率則可達90%以上。 本試驗以複迴歸分析不同照光時間、過硫酸鹽濃度及紫外光強度三種參數，找出五氯酚鈉降解影響之主要因素，得知，紫外光強度>照光時間>過硫酸鹽濃度。
並列摘要
The study was to oxidize Sodium Pentachlorophenol contaminated groundwater by using Sulfate radical (SO4-‧) and hydroxyl radical (OH‧) generated under the reaction of Persulfate photocatalyzed by ultraviolet light with wavelength 254 nm. The experiments was arranged to determine degradation efficiency of Sodium Pentachlorophenol (PCP-Na) by varying both strength of ultraviolet light and exposure time. The combination of PCP-Na and ultraviolet light were 150 mg/L, 300 mg/L, 450 mg/L, 600mg/L and 80 μW/cm2, 470 μW/cm2, 2260 μW/cm2 respectively with fixed concentration of 4.2 mM Persulfate and exposure time from 0.5 to 24 hours. The volume ratio 40 mL : 1 mL of PCP-Na and Persulfate was made for the subsequent undertakings in the laboratory. In the very beginning, the degradation of PCP-Na was checked with and without exposure of ultraviolet light. For PCP-Na oxidized by Persulfate, the results concluded that, without ultraviolet, only 10% degradation was achieved whereas, with ultraviolet light, approximately 80% of PCP-Na was found rapidly removed. With the aforementioned understanding, the following studies thus focused on the characteristic of using ultraviolet light to catalyze the oxidation of PCP-Na by Persulfate. At least 3 parameters involved in this study were systematically checked. The arrangement of ultraviolet light strength between 80 μW/cm2 and 470 μW/cm2 with exposure time between 0.5 to 24 hours was set to conduct and found only 10% of PCP-Na was removed. By increasing the strength of ultraviolet light up to 2260 μW/cm2 , the degradation of PCP-Na can reach 14% with exposure time of 0.5 hour whereas at least 90% can be obtained when exposure time was set to 12 hours. As previously mentioned 3 parameters involved in this study were carefully checked by means of cross reference and then analyzed by method of multiple regressions. To understand the priority of these 3 parameters subject to the degradation of PCP-Na, the result obtained showed the effective factor is strength of ultraviolet light > exposure time > concentration of Persulfate.
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