Kinetics of formation and degradation of hexenuronic acid during kraft cooking | |
| Author | Saha, Ananda Mohon |
| Call Number | AIT Thesis no.PP-05-08 |
| Subject(s) | Pulping Wood-pulp--Bleaching Sulphate pulping process |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science |
| Publisher | Asian Institute of Technology |
| Abstract | The formation and degradation of Hexenuronic acid during kraft pulping of Eucalyptus camuldulensis, Acacia mangium and mixed softwood (Picea abies and Pinus silvestries) were investigated in this study. For both the species HexA content started to increase and reached its highest point after about 10-13 minutes cooking at the cooking temperature, then it sta1ied to decrease. For eucalyptus the highest HexA content was 67.2 mmol/kg and 69.2 mmol/kg for 19% E.A and 21% E.A charge respectively at 165°C temperature. For acacia it was comparatively lower (48.1 mmol/kg and 50.9 mmol/kg at 21% E.A and 19% E.A charge respectively at 165°C temperature.). HexA reduction in cooking was 30% for eucalyptus and about 55% for acacia. When cooking temperature was decreased to 155°C and maintained the same H factor, HexA content raised about 2-3 units for both the species. HexA content was also related to kappa number and lignin content. In case of mixed softwood pulp the same trend was observed but HexA content was lower than that of eucalyptus and acacia. Highest HexA content of softwood was 39.8 mmol/kg and at the end of cooking it reduced to 16.1 mmol/kg. It was found that oxygen delignification had no significant effect on HexA content. After D0Ep stages the unbleached pulp with higher HexA content showed lower final brightness. After final bleaching, 92.1% HexA reduction was achieved for eucalyptus and 89.1% for acacia, cooked with 21% E.A and at 165°C temperature. Considering the formation and degradation of HexA, cooking at 165°C temperature and 21% E.A charge was found to give lowest HexA content. |
| Year | 2005 |
| 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 | Pulp and Paper Technology (PP) |
| Chairperson(s) | Malinen, Raimo O.; |
| Examination Committee(s) | Kolehmainen, Heikki ;Lehtinen, Esa ; |
| Scholarship Donor(s) | Government of Finland ;AIT Fellowship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2005 |