27. Hollow Chitosan Fibers

Hollow chitosan fibers (Fig. 27.1) were fabricated by removing unprecipitated chitosan through air and water flow [01Vin, 08Ara]. These hollow fibers have been used for various applications. For instance, hollow chitosan fibers were used to extract Cr(VI) with aliquot 336 by assembling the hollow fibers into a module and circulating the metal ion solution and extract inside the hollow lumen. It was observed that Cr(VI) ions were sorbed on the fiber and also by solvent which flowed through the fiber. Reacetylation of the fiber maintained the efficiency of extraction and also increased the mechanical and chemical resistance [01Vin]. Hollow chitosan fibers supported with palladium were also used to degrade nitrophenol found in industrial waste waters [04Vin]. A sodium formate system and a hydrogen system were used, and the former was found to be more efficient. Experimental parameters such as residence time, recycling, and concentration of the chemicals were reported to determine the efficiency of degradation. Similarly, palladium-supported chitosan fibers were also used as a catalytic system for hydrogenation of nitrotoluene [08Blo]. The diffusion of biological agents such as tryptophan, chloramphenicol, amoxicillin, and vitamin B12 through hollow chitosan fibers was investigated to understand the potential of using the fibers as nerve guide channels [08Pei]. pH of the permeant was found to have the most significant impact on permeability with the permeability coefficient decreasing with the molecular weight of the permeant. These fibers were considered suitable for catalysis and support for biological molecules or enzymes or for controlled drug release and enzyme immobilization [08Pei]. Hollow chitosan/cellulose acetate fibers were produced by wet spinning for use as absorptive membranes for affinity-based separations [05Liu]. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) studies showed interactions between cellulose acetate and chitosan. Blend fibers had good tensile properties and showed high surface absorption for copper ions and bovine serum albumin [05Liu]. Absorption of copper up to 30 mg/g of chitosan and 8 mg/g of bovine serum albumin was obtained.