Characterization and Immobilization of a Marine Laccase for the Degradation of Aromatic Compounds in a Packed bed Reactor

Guresci, Nazmiye (2019) Characterization and Immobilization of a Marine Laccase for the Degradation of Aromatic Compounds in a Packed bed Reactor. [Laurea magistrale], Università di Bologna, Corso di Studio in Ingegneria per l'ambiente e il territorio [LM-DM270], Documento full-text non disponibile
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Industrial wastewater pollution caused by aromatic compounds is still of high concern due to their toxicity and carcinogenicity. The aim of this thesis was to characterize and immobilize a marine laccase for the biodegradation of phenolic pollutants, such as Bisphenol A (BPA) and catechol, in a packed bed reactor. The enzyme (1 U/ml) was not active on BPA (20 mg/L) while it was able to oxidize catechol (20 mg/L). Its maximal activity was reached at 30 °C, pH 6, with Km of 0.62 g/l and Vmax of 6.9 mg/l/min (0.7 U/ml). Different concentrations of enzyme (15, 7.5 and 3 mglaccase/gresin) were tested for immobilization on an ethylamine-functionalized resin. The immobilization yield increased with the decrease of the initial enzymatic concentration, ranging from 72.8 to 99.5%. The immobilized laccase had a residual activity greater than 80% if stored dry at 4 °C, whereas it significantly lost activity if incubated in water or buffer pH 6 at 30 °C, but not at pH 7, due to its detachment from the resin. The immobilized laccase (0.7 U/ml) was able to remove up to 85% of catechol (20 mg/l) in 2 hours. In parallel, preliminary tests showed a marked adsorption of catechol on the immobilization resin. Packed column reactors (88 ml) were designed and set up with: i) resin with immobilized laccase (167.2 U/gresin) and ii) resin with immobilized bovine serum albumin, as abiotic control. Fluid dynamic test showed a resin porosity of 95%, corresponding to an enzyme concentration of 151.7 U/mlreactor. The columns were fed in continuous from the bottom with oxygen-saturated water contaminated by catechol (20 mg/l). A significant reduction of catechol concentration occurred in the control column due to abiotic phenomena, such as adsorption to the resin and oxidation. However, the enzymatic degradation reaction was faster, allowing the laccase column to completely remove catechol.

Tipologia del documento
Tesi di laurea (Laurea magistrale)
Autore della tesi
Guresci, Nazmiye
Relatore della tesi
Correlatore della tesi
Corso di studio
Earth resources engineering
Ordinamento Cds
Parole chiave
Laccase,enzyme immobilization,Packed-bed reactor
Data di discussione della Tesi
15 Marzo 2019

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