| Summary: | 碩士 === 朝陽科技大學 === 環境工程與管理系碩士班 === 99 === 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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