| Summary: | 碩士 === 國立交通大學 === 環境工程與科學系 === 85 === Catalytic degradation of 2-chlorophenol has been investigated in the α-FeOOH/H2O2 process. There are four parts in this research. First, a background test was carried out. Second, controlling factors, such as initial 2-chlorophenol concentration, hydrogen peroxide concentration, goethite concentration, goethite particle size, pH, temperature, different chlorophenol compounds and electrolytes were investigated. Third, the reaction mechanism in this process was studied. Finally, the reaction kinetic model of 2-chlorophenol degradation was also proposed.
The results are shown as follows. The rate of 2-chlorophenol oxidation increases with decreasing 2-chlorophenol initial concentration and increasing initial hydrogen peroxide and goethite loading. Effect of goethite particle size on the 2-chlorophenol oxidation is very signficant; the smaller goethite particle size, the faster 2- chlorophenol oxidation. The rate of 2-chlorophenol oxidation is highest at pH=2~3 . Three lands of chlorophenols were degraded compounds by α-FeOOH/H2O2, and the oxidation rate of these chlorophenols is shown as below :
2-CP>4-CP>2,4-DCP
This process is sensitive to electrolytes. It was found that the effect of electrolytes on the oxidation rate follows the order:
H2PO4- > Cl- > NO3- > ClO4-
Goethite can be dissolved to produce ferrous ions and the dissolution reaction can be shown as follows:
α-FeOOH＋1/2H2O2＋2H+ → Fe2+＋1/2O2＋2H2O
Ferrous ions can produce Fenton reaction with hydrogen peroxide, and hence 2-chlorophenol can be degraded by Fenton reaction. The oxidation of 2-chlorophenol with α-FeOOH/H2O2 in this study is a two-stage reaction. In the first stage, 2- chlorophenol oxidation is limited by the amount of ferrous ions forming in the reaction solution. In the second stage, after 100 minutes of reaction time, the rate of 2- chlorophenol oxidation suddenly increases, and can be described with a zero-oder kinetics.
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