Investigation of gas permeability in chitosan tablets

In this thesis, permeability of gases in chitosan tablets was investigated. The permeability fluxes were measured using Wicke-Kallenbach type diffusion/adsorption cell. A commercial chitosan (CC) and synthesized chitosan (SBC) from shrimp shell samples were used in the experimental studies. Tracer gases were selected as Ar, N₂, CO₂, and CH₄. The permeability tests were performed at pressure drop from 0 kPa (isobaric) to 12 kPa and at 25-80 °C. The tablets were prepared with tablet porosities in the range of 0.115-0.454 for CC and 0.079-0.415 for SBC. In this study, true density, particle size distribution, FTIR, SEM-EDX, and elemental analysis of chitosan samples used in experimental studies were also performed. From FTIR analyses, it was observed that there are similar functional groups on the surface of studied chitosan samples. From SEM images, it was determined that CC has porous, microstructure, and smooth surface. SBC has also similar SEM properties, but it's surface was rough. EDX analyses showed that CC is purer than SBC. From elemental analysis, it was observed that both chitosan samples contain C, H, and N. The percentages of these element in the CC was greater than those of SBC. The true density and mean particle size values of CC were measured as 1,4706 g/cm³ and 71,1119 μm, respectively. True density of SBC was 1,6712 g/cm³. The mean particle size values of un-milled and milled SBC samples were 105,697 μm, and 90,8307 μm, respectively. As a result of permeability experiments, the best selectivity value was obtained in CC-2 tablet for CH₄/CO₂ gas couple. Also, the surface diffusion of CO₂ occurred in the CC-2 tablet. Permeability values of gases in the CC tablets were lower than those of SBC tablets. However, from selectivity values of SBC tablets, it has been understood that it can also be used as a gas enrichment agent. In the light of the results of this thesis, it is recommended that researchers who will work in this field should perform optimization studies for gas permeability in chitosan tablets.