Evaluation of the potential of chitosan hydrogels to extract polar organic species from nonpolar organic solvents: Application to the extraction of aminopyridines from hexane

The extraction of a series of aminopyridines (APs) utilizing chitosan hydrogels in hexane was investigated. The chitosan hydrogel was prepared using glutaraldehyde as a cross-linking agent. Experiments were carried out to determine the maximum extraction efficiency, distribution coefficient, sorption capacity, and adsorption and desorption mechanisms. The efficiency of extraction of aminopyridines attained a maximum value of ca. 100% with the distribution coefficients for the transfer of the aminopyridines from hexane to chitosan hydrogel increasing in the order of ortho- < meta- < para-AP. The Langmuir sorption model described the equilibrium data quite well, yielding sorption capacities of 11.37 mg (o-AP), 21.03 mg (m-AP), and 29.33 mg (p-AP) per gram of chitosan hydrogel. Methanol was found to be effective for the subsequent desorption and recovery of APs from the CHG, allowing for recycling of the CHG sorbents. The results demonstrate that CHG can be employed for the extraction of organic species from organic solvents which should serve to expand of the scope of applications for such chitosan materials. (C) 2008 Elsevier Inc. All rights reserved.