Effects of organic acids and salt concentrations on chitosan membrane properties | |
| Author | Nguyen Thi Quy |
| Call Number | AIT Thesis no. BP-02-11 |
| Subject(s) | Chitosan Organic acids |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis no. BP-02-11 |
| Abstract | The membrane prope1iies of two chitosan samples were examined by using six different organic solvents (formic, acetic, propionic, glycolic, lactic and citric acid) as dissolving solvents. Their degrees of deacetylation (DD) are 70% (termed low DD) and 95% (termed high DD). Both chitosans are having a weight average molecular weight of 0.8 M Dalton. The physico-chemical properties of the membranes prepared from these organic acids were characterized. Both degree of deacetylation and the organic acids used affected the membranes properties. The X-ray diffraction patterns indicated that high DD membranes possess three major peaks at 10°, 15° and 20° (28) whereas low DD membranes have their sole peak at 10° (28). High DD membrane prepared from formic, glycolic and citric acids are having relatively lower crystallinity than membranes from other solvents. It is observed that the tensile strength and elongation-at-break increases as the DD increased; however, the swelling index, biodegradability through lysozyme activity and permeability of membranes with sodium salicylate reduced. Propionic acid improved significantly the tensile strength in both low and high DD membranes but gave the lowest pe1meation rate in case of high DD membrane, while glycolic and formic acid resulted in the lowest tensile strength but highest permeability among high DD membranes. Both low and high DD chitosan membrane produced from lactic acid were most resistant to lysozymic degradation. Jn contrast, the low DD citric membrane has been most susceptible to lysozyme. Effect of sodium chloride concentration on preparing chitosan membrane properties was examined. The increase of sodium chloride concentration in the tested range of 0-0.3% reduces crystallinity of the high DD membranes but increases peak intensity of low DD membranes. The increase of sodium chloride concentration increases the swelling index of chitosan membranes. For low DD membrane, sodium chloride in the range of 0 to 0.1 % improved significantly tensile strength but no significant effect on high DD membrane has been observed. There is a sharp reduction in the tensile strength when sodium chloride concentration is increased to 0.3%. This effect ha been more significant in the high DD membranes. Elongation-at-break reduces as sodium chloride concentration increased. Salt concentration is also observed to have an effect on biodegradability and permeability of membrane. Sodium chloride at 0.05% leads to fastest degradation of low DD membrane but no significant effect on high DD membrane. Beyond the other salt concentrations were resistant to lysozyme for both low and high DD membranes. Permeability was increased when low DD membrane was added with 0.05% NaCl; it reduced when the membrane was treated with 0.3% NaCl. The permeability characteristics of high DD membranes have been reversed to that of low DD membranes. Treatments with 0.05 and 0.1 % salt reduce the permeability, whereas it was increased for high DD membrane if 0.3% salt was introduced. This result has been consistent with the X-ray diffractograms of membranes with salt. |
| Year | 2002 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis no. BP-02-11 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Bioprocess Technology (BP) |
| Chairperson(s) | Stevens, Willem F.; |
| Examination Committee(s) | Suwalee Chandrkrachang ;Suwabun Chirachanchai ;Traenkler, Josef; |
| Scholarship Donor(s) | New Zealand; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2002 |