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环境科学学报 2013
Bentonite modified with cetyltrimethylammonium chloride as highly efficient anion exchanger for perchlorate ion
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Abstract:
Cationic surfactant cetyltrimethylammonium chloride (CTAC) was employed to modify a bentonite for enhancing its adsorption for perchlorate. The results showed that CTAC modification greatly improved adsorption of bentonite. The perchlorate uptake on CTAC-bentonite from 0.1 to 1 mmol·L-1 solution rapidly attained equilibrium within 6 h. The perchlorate uptake on CTAC-bentonite followed the Langmuir isotherm model with capacity of 0.48 mmol·g-1. In addition, the adsorption capacity persisted in a wide pH of 4~10. High selectivity of CTAC-bentonite for perchlorate ion was reflected in the high distribution coefficient values (>1.5×103 cm3·g-1) with selectivity sequence of HPO42- < SO42- < NO3-< ClO4-. This selectivity sequence corresponded to the sequence of increasing hydration energy of anions. CTAC-bentonite regeneration using 1 mol·L-1 of HCl solution was investigated, which showed efficiency of 96%. CTAC-bentonite could be reused directly after regeneration with 1 mol·L-1 of HCl solution.