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| Adsorption of Phenol on Amphoteric-Cationic Modified Bentonites |
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| KeyWord:combined modification; phenol; amphoteric-cationic modifier; bentonite; adsorption |
| Author Name | Affiliation | | LI Bin | College of Science, Northwest A&F University, Yangling 712100, China | | MENG Zhao-fu | College of Natural Resource and Environment, Northwest A&F University , Yangling 712100, China
Key Laboratory of Plant Nutrition and Agri-Environment in Northwest China, Ministry of Agriculture, Yangling 712100, China | | WANG Jian-tao | College of Natural Resource and Environment, Northwest A&F University , Yangling 712100, China | | MA Lin-li | College of Natural Resource and Environment, Northwest A&F University , Yangling 712100, China | | XU Shao-e | College of Natural Resource and Environment, Northwest A&F University , Yangling 712100, China | | YANG Shu-ying | College of Science, Northwest A&F University, Yangling 712100, China |
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| Abstract: |
| Modified bentonites have been used as an adsorbent for environmental remediation. An experiment was designed to examine the adsorption of phenol on bentonites modified by a mixture of amphoteric modifier, dodecyl dimethyl betaine（BS-12）, and cationic modifier, hexadecyltrimethylammonium bromide（CTMAB） as influenced by modifier ratios, ionic strength, temperature and pH. Adsorption capacity of phenol on bentonites was in order of 100BS+100CT（100%BS-12+100%CTMAB）>100BS+50CT（100%BS-12+50% CTMAB）>50BS+100CT（50%BS-12+100%CTMAB）>100BS+150CT（100%BS-12+150%CTMAB）>50BS+50CT（50%BS-12+50%CTMAB）>100BS+25CT（100%BS-12+25%CTMAB）>50BS+150CT（50%BS-12+150%CTMAB）>50BS+25CT（50%BS-12+25%CTMAB）>100BS（100%BS-12）>50BS（50%BS-12）>CK（unmodified soil）. This revealed that the adsorption of phenol on modified bentonites increased with increasing CTMAB ratios at 0~100% of CEC, while decreased slightly at CTMAB ratios greater than 100% of CEC. The phenol adsorption was reduced by elevated temperature and pH, but increased with ionic strength at low concentration ranges. Henry equation could best describe the phenol isotherms. The adsorption of phenol on amphoteric-cationic modified bentonites is a spontaneous physical adsorption process characteristized by both enthalpy decreases and entropy increases. |
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