Using Chemical Oxidation Methods to Degrade Chlorophenols in Groundwater

• Main Authors: Wei-Jun Lin, 林偉俊
• Other Authors: Min-Hsin Liu
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/09034054581467620417

碩士 === 朝陽科技大學 === 環境工程與管理系碩士班 === 98 === Chlorophenols compound, which does not exist in natural environment, is 100% an artificial and synthetic chemical prepared from variable chemicals. Chlorophenols compound has been recognized one of the most recalcitrant chemicals. Among them, pentachlorophenol, as an organic contaminants with low solubility found in the soil or groundwater, to achieve degradation, the method of those like in-situ chemical oxidation has been widely undertaken. Persulfate and Fenton reagents are the oxidation regents which both rely on free radical in chemical oxidation process. Although both reagents possess similar oxidation capability, persulfate reagent is relatively stable and capable of creating larger influence radius and also persistence while applying in given remediation process. Therefore, persulfate has been widely used in in-situ chemical oxidation method nowadays. This study aims at dosing 2,4,6-trichlorophenol, pentachlorophenol and its sodium salts, to uncontaminated groundwater. Unsaturated 2,4,6-trichlorophenol groundwater, over-saturated groundwater of pentachlorophenol, and unsaturated groundwater of sodium pentachlorophenol were prepared, and groundwater pH value, redox potential and total organic carbon values, etc. were measured in each groundwater sample. For study of chemical oxidation, experiments were introduced for methods of Fenton oxidation and persulfate oxidation. In the Fenton test, for 2,4,6-trichlorophenol in groundwater samples, the best degradation of pollutants was obtained with the condition of 14.4 mM hydrogen peroxide and 206 mM ferrous sulfate as catalysts and with pH value 4. In the persulfate oxidation test, for pentachlorophenol and its salts in groundwater samples, the dosage used are 16.8 mM sodium sulfate and 14.4 mM ferrous sulfate. With above condition, the removal efficiency of pentachlorophenol was found can be up to 94% under the volume ratio of groundwater, Sodium sulfate and ferrus sulfate of 20: 1.1: 1.1. The persulfate oxidation was also found its effect of degradation, very likely from the effect of the remaining persulfate, can be prolonged while higher concentration of pentachlorophenol was continually introduced into the groundwater samples. And data from the results of experiments shows that the dosage of ferrous sulfate can effectively give impact of the catalytic reaction by sodium sulfate, and then dominates the degradation of pentachlorophenol. However, over dosing the ferrous sulfate, on the contrary, can not effectively degrade the pentachlorophenol, but very likely caused more pollution onto our fragile nature.