外文化学吸附及亚甲基蓝.pdf

Adsorption Kinetics and Thermodynamics of Methylene Blue onto p-tert-Butyl-calix[4,6,8]arene-Bonded Silica Gel Ming Chen, Yun Chen, and Guowang Diao* College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, P. R. China, and Key Laboratory of Environmental Materials Environmental Engineering of Jiangsu Province, Yangzhou, Jiangsu, 225002, P. R. China New-style adsorbents of p-tert-butyl-calix[4,6,8]arene-bonded silica gelsCnABS (C4ABS, C6ABS, C8ABS)swere prepared by bonding p-tert-butyl-calix[4,6,8]arene to the silica gel surface through the coupling reagent, 3-glycidoxypropyltrimethoxysilane. The products were characterized by FTIR, thermogravimetry, elemental analysis, and scanning electron microscopy. The adsorption of methylene blue from aqueous solution by CnABS was studied. Kinetic studies showed that the adsorption of the dye onto CnABS fit a first-order kinetic model. The equilibrium adsorption data were interpreted using the Langmuir and Freundlich models. The adsorption of methylene blue onto CnABS was better represented by the Langmuir equation. The saturation adsorption quantity monotonically increased with the number of phenolic units in the calixarene ring. The thermodynamic parameters for the adsorption reaction were calculated through a van’t Hoff analysis. The whole adsorption process was endothermic, which resulted in an increase of the adsorption quantity with a temperature increase. The new-style adsorbent of CnABS was regarded as a potential adsorbent to deal with dyes or organics in wastewaters. Introduction Azo dyes are important colorants having extensive application in the leather, textile, paper mill, additive, foodstuff, and cosmetic industries. However, approximately (10 to 15) % of the overall production of azo dyes is released into the environ- ment, which is very dangerous because some of the azo dyes and their degradation products have a toxic, carcinogenic, or mutagenic influence on living organisms. There