Application of Fenton process in the degradation of carbofuran contaminated water

• Main Authors: Yi-Shiung Su, 蘇義雄
• Other Authors: Jih-Gaw Lin
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/32498309965091270823

碩士 === 國立交通大學 === 環境工程系所 === 96 === Carbofuran (C12H15NO3) is a broad spectrum, carbamates insecticide widely used to control certain soil-borne insects and nematodes. In Taiwan, carbofuran accounts for about 7% of the 15478 tons of insecticides produced per year. Carbofuran usage has received intensive concern not only due to its heavy use but also due to its high oral toxicity. The wastewater treatment processes using the Fenton reaction are known to be very effective in the removal of many hazardous organic pollutants from water. In this study, Fenton process was applied to remove carbofuran from aqueous system. Fenton experiments were conducted in batch mode at two different carbofuran concentrations i.e. 10 and 50 mg/L and at fixed initial pH of the system i.e. pH 3. Batch experiments at each carbofuran concentrations were designed by central composite design (CCD) with two independent variables i.e. Fe2+ and H2O2. The efficiency of the experiments was determined based on the percentage removal of carbofuran. Finally, a statistical experimental design and the response surface methodology were used to optimize the Fe2+ and H2O2 concentrations for maximum percentage removal of carbofuran. More than 90% of carbofuran removal was observed within 5 min of Fenton reaction with Fe2+ concentration above 5 mg/L and H2O2 concentration above 100 mg/L. The increase in Fe2+ and/or H2O2 concentrations beyond 5 and 100 mg/L, respectively, produced 100% carbofuran removal in the Fenton process. No carbofuran removal was observed when either Fe2+ or H2O2 was absent in the system. Based on the experimental observations, the optimal Fe2+ and H2O2 dosages required for 10 mg/L of aqueous carbofuran removal were estimated as 7.4 and 143 mg/L, respectively. Carbofuran degradation experiments were repeated at optimal Fe2+ and H2O2 concentrations and the samples were collected at various time intervals. The collected samples were analyzed in gas chromatography-mass spectrometry (GC-MS) for the determination of carbofuran degradation pathway. The GC-MS analysis indicated that carbofuran was oxidized to 7-benzofuranol,2,3,-dihydro-2,2-dimethyl (m/z 164), 7-hydroxy-2,2-dimethyl-benzofuran-3-one (m/z 178) and 1,4-Benzene-di- carboxaldehyde (m/z 134).