| Summary: | 碩士 === 弘光科技大學 === 環境工程研究所 === 98 === Chlorophenols are common organic pollutants found in the water environment, which causes serious impact on human health and environment. In general, chlorophenols can be treated by (1) Solvent extraction; (2) Activated carbon adsorption; (3) Incineration; (4) Biological treatment; (5) Photocatalytic; and (6) Chemical oxidation process in wastewater. However, those technologies are with their own limitations. Thus, to develop new integrated technologies became the major goal of environmental research groups. Recently, there are some literatures presented nano-scaled zero-valent Iron can be used to treat chlorophenols wastewater with very good dechlorination efficiency. Nano-scaled particles are very hard to be handled which makes the scale-up very difficult. Therefore, the aim of this work is to utilize the ion exchange resin as the carrier of nano-scaled zero-valent metals to overcome the difficulties of nano-particle operation and reaches the higher treatment efficiency and ease to operate.
In this study, complex of cation exchange resin carrier and nano-metals was utilized to treat 2-chlorophenol wastewater in a batch reactor. The operating parameters such as 2-chlorophenol initial concentration, pH, mixing speed, reaction temperature and dosage of nano-scaled metal were investigated to verify the effects of operating parameters on dechlorination of 2-CP. Secondly, a packed bed column reactor with resin carrying nano-scale metals packing was setup and tested.
The experimental results from the batch system shown that the stirring speed of 200 rpm presented the best dechlorination efficiency. Higher initial 2-chlorophenol concentration caused low dechlorination efficiency. The operating pH affected dechlorination significantly. Under extreme pH conditions such as pH 2 and pH 11, the dechlorination reaction were inhibited, the final removal efficiencies were 74.7% and 41.8% for pH 2 and pH 11, respectively. For mild condition, such as pH 4, a 2-chlorophenol dechlorination efficiency of 94.4% can be reached in 30 minutes of reaction time. The highest efficiency of the dechlorination was observed at 60 oC. In this study, the metal ratio of 35.3 mgFe 19.6 mgNi/g-resin performed the best dechlorination efficiency. And all experimental results have shown that the reaction kinetics is closed to a first-order reaction.
For packed column experiments, in defined operation conditions of this work, the breakthrough volume of 2100 ml and the exhaust volume of 3900 ml were obtained for Ni/Fe bimetallic coating resin. In order to verity the feasibility to apply to a column test was performed a real plant. 2-chlorophenol concentration in column test maintained zero for certain time up to 420 minutes and reached breakthrough point. Then the 2-CP concentration in creased to about 0.64 mM as exhaust point. By using the optimal operating conditions, 2,4-dichlorophenol was also tested for dechlorination and reach a 70% of dechlorination efficiency.
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