Mushroom tyrosinase (polyphenol oxidase, EC 1.14.18.1) was investigated as an alternative to peroxidase, enzymes for the catalytic removal of phenolic compounds from wastewaters. The maximum catalytic activity was observed at pH 7; however, significant activity was observed at pHs ranging from 5 to 8. Tyrosinase was unstable under acidic conditions and at elevated temperatures. The activation energy for thermal inactivation of tyrosinase was determined to be 1.85 kJ mol-1 at pH 7. The transformation of phenols catalysed, by tyrosinase was investigated as a function of pH, initial phenol concentration, and additives. Phenol was transformed successfully with tyrosinase, over a wide range of pH (pH 5--8) and a wide range of initial concentrations (0.5 mM--10 mM). Some chlorinated phenols were also successfully transformed with tyrosinase. Polyethylene glycol and chitosan did not improve the transformation efficiency of phenol. However, chitosan was successfully used to remove coloured, products resulting from treatment Since coagulation with aluminium sulfate failed, the colour removal induced by chitosan addition appeared to be the result of simultaneous coagulation and adsorption mechanisms. Minimum doses of chitosan required to achieve 90% of colour removal were logarithmically related to the quantity of phenol treated. All solutions of phenol and chlorophenols treated with tyrosinase, had substantially lower toxicities, than their corresponding initial toxicities. Chitosan addition enhanced the reduction in toxicity very effectively. The toxicities of the phenol solutions treated with tyrosinase were markedly lower than previously reported toxicities of solutions treated with peroxidase enzymes.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.21304 |
| Date | January 1999 |
| Creators | Ikehata, Keisuke. |
| Contributors | Nicell, James A. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Civil Engineering and Applied Mechanics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001658662, proquestno: MQ50624, Theses scanned by UMI/ProQuest. |
Page generated in 0.0371 seconds