Mechanism of removing chlorophenolic compounds from solution by a water-insoluble cationic starch |
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Authors: | Wu-Chung Chan Tzu-Ping Fu |
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Affiliation: | (1) Civil Engineering Department, Chung-Hua Polytechnic Institute, Hsinchu, 30067, Taiwan, R. O. C. |
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Abstract: | The removal of three chlorophenolic compounds from solutions using highly crosslinked cationic starch containing a tertiary
amine group was investigated. The three chlorophenolic compounds were 2-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol.
The adsorption process predominated over the initial pH = 2∼6 for 2-chlorophenol, and predominated over the initial pH = 2
to 4 range for 2,4-dichlorophenol and 2,4,6-trichlorophenol. The ion-exchange process predominated at initial pH = 12 for
2-chlorophenol, and predominated over the initial pH = 10 to 12 range for 2,4-dichlorophenol and 2,4,6-trichlorophenol. Both
processes coexist over the initial pH=8 to 10 range for 2-chlorophenol, and coexist over the initial pH = 6∼8 for 2,4-dichlorophenol
and 2,4,6-trichlorophenol. Experimental results indicate that the adsorption process is initially pH-independent, and the
ion-exchange process is initially pH-dependent. The adsorption and ion-exchange processes are concentration-dependent and
correspond to the Langmuir isothermal adsorption. They are endothermic for 2-chlorophenol and 2,4-chlorophenol, and are exothermic
for 2,4,6-chlorophenol. The ion-exchange capacity is larger than the adsorption capacity. Moreover, the order of the amount
of three chlorophenolic compounds removed by the cationic starch is 2,4,6-chlorophenol > 2,4-dichlorophenol > 2-chlorophenol. |
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Keywords: | Chlorophenolic compounds Tertiary amine Water-insoluble cationic starch Adsorption Ion-exchange |
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