Adsorption Studies of Cu2+/Zn2+ Binary Component Aqueous Solution on Chitosan：Adsorption Isotherms and Breakthrough Curves

• Main Authors: Guo Liang Lin, 林國良
• Other Authors: T. S. Lu
• Format: Others
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/51358693929695028000

碩士 === 長庚大學 === 化工與材料工程學系 === 98 === Adsorption of aqueous Cu2+ and Zn2+ on flaky chitosan are carried out in a stirred batch reactor. Langmuir type and Freundlich type equations are used to fit the single component adsorption isotherm. The smaller average error for Langmuir isotherm (6-23%) shows that Langmuir isotherm is better than Freundlich isotherm to express the adsorption equilibrium. For pH in the range of 3 to 5, adsorption capacities of Cu2+ and Zn2+ increases with the increase of pH. The experiment results show that chitosan is favor to adsorb Cu2+. The diffusivities of Cu2+ and Zn2+ in the chitosan are 2.57×10^-8 and 1.25×10^-8 cm2/s respectively. Extended Langmuir isotherm and ideal adsorbed solution theory (IAST) are applied to the two component system. Langmuir isotherm and Freundlich isotherm are combined with IAST to calculate the spreading pressure. The errors of the extended Langmuir isotherm, IAST-Langmuir, and IAST-Freundlich all fall in the range of 31-37%, which means that the three models are equal well to express the adsorption isotherms of Cu2+/Zn2+ binary-component system. Fixed bed packing with flaky chitosan was utilized to take the breakthrough curves of Cu2+ and Zn2+. Effects of bed length and feed concentration on the breakthrough point were experimentally investigated. The results show that increases the bed length or decreases the feed concentration, increase the breakthrough point. For the binary component system, zinc ion breakthrough early than copper ion. The breakthrough curve of zinc ion rolls up in a certain period of time, which indicates that Cu2+ replace Zn2+ during the adsorption process in the bed. Two developed dispersed plug flow-linear driving force models of adsorption column for single and binary component systems can simulate the breakthrough curves quite well.