Fundamental adsorption properties of chitosan gel particles prepared by suspension evaporation method

Abstract

Chitosan gel particles were prepared by the suspension evaporation method, and their fundamental adsorption properties have been investigated. The chitosan gel particles were spherical in shape, 150 m in diameter, and had large macropores, about 2 m in diameter, formed by the polymer networks. The adsorption properties were evaluated from an interaction viewpoint using anionic surfactants having various numbers of carbon atoms, ethylbenzenesulfonate (EBS), octylbenzenesulfonate (OBS), and dodecylbenzenesulfonate (DBS). The pK a values of the amino groups within the gel particles were remarkably small compared with those of chitosan polymer. EBS, with its short hydrophobic chain, was adsorbed mainly by an electrostatic interaction in the pH range 3.0 to 6.0, where the amino groups were dissociated. On the contrary, the adsorption of OBS and DBS, with their relatively long hydrophobic chains, took place via an electrostatic interaction in the pH range 3.0 to 5.0, and then by a hydrophobic interaction in the presence of an electrostatic interaction in the pH range 5.0 to 8.0. We conclude that an electrostatic interaction is essential, even for the adsorption of surfactants having strong hydrophobic interactions.

Pervaporation separation of isopropanol/water mixtures through crosslinked chitosan membranes

“…groups are more interactive than hydroxyl groups), R-NH 2 present in the membrane which decreased upon crosslinking [31]. This shows that almost 50% of the amine groups present in the unmodified chitosan have now formed the crosslinks with TDI.…”

Dehydration of tetrahydrofuran by pervaporation using crosslinked PVA/PEI blend membranes

“…It was noted that uncrosslinked blend showed an IEC of 0.30 meq/g, whereas the crosslinked blend membrane exhibited an IEC of 0.13 meq/g. The IEC, which is equivalent to the total number of free amino groups (considering the fact that amino groups in the blend are more reactive when compared to hydroxyl groups), decreased after crosslinking 42. This shows that almost 60% of the amine groups present in the unmodified blend have now formed crosslinks with GA and there are still a few amine and hydroxyl groups left for sorption and diffusion of water molecules through the blend, thereby excluding the possibility of formation of the homolinks.…”

Smart Textile Materials by Surface Modification with Biopolymeric Systems

“…Since chitosan has excellent hydrogel forming properties, another approach is to control the micro-and macrostructure of the chitosan gel itself without any chemical modification. The structure and properties of chitosan gels may be varied by the appropriate choice of the preparation method used (Igarashi, et al 2002), and by blending two or more polymers to obtain the desired properties, latter method being now a common practice.…”