Kinetic and Thermodynamic Studies of Toluene, Ethylbenzene, and m-Xylene Adsorption from Aqueous Solutions onto KOH-Activated Multiwalled Carbon Nanotubes

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• 作者：Fei Yu ; Yanqing Wu ; Xiaoman Li ; Jie Ma
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2012
• 出版时间：December 19, 2012
• 年：2012
• 卷：60
• 期：50
• 页码：12245-12253
• 全文大小：428K
• 年卷期：v.60,no.50(December 19, 2012)
• ISSN：1520-5118

文摘

Multiwalled carbon nanotubes activated by KOH (CNTs-KOH) were synthesized and employed as adsorbents to study adsorption characteristics of toluene, ethylbenzene, and m-xylene (TEX) from aqueous solutions. Kinetics data were fitted by pseudo-second-order model, and intraparticle diffusion was not the only rate-controlling step. Adsorption isotherm data could fit well with Langmuir, Freundlich, and Dubinin鈥揜adushkevich (D-R) models. The maximum adsorption capacities on CNTs-KOH are 87.12, 322.05, and 247.83 mg/g for toluene, ethylbenzene, and m-xylene, respectively. The adsorption capacities of TEX onto CNTs-KOH increased with contact time and decreased with temperature and are not significantly affected by humic acid. However, Cr⁶⁺ could decrease adsorption of TEX by 17.66, 4.51, and 12.69% as (K_d¹ 鈥?K_d²)/K_d¹, respectively. The thermodynamics parameters indicated that adsorption was a feasible, exothermic, and spontaneous process in nature and a physisorption process. The present CNTs-KOH show a better EX adsorption performance than other adsorbents, suggesting that CNTs-KOH are promising EX adsorbents in wastewater treatment.

Keywords:

adsorption; TEX; activated multiwalled carbon nanotube; kinetics; thermodynamics; chromium(VI)