Impacts of redox-mediator type on trace organic contaminants degradation by laccase: Degradation efficiency, laccase stability and effluent toxicity
Journal
International Biodeterioration and Biodegradation
Journal Volume
113
Pages
169-176
Date Issued
2016
Author(s)
Abstract
This study compares the effectiveness of seven redox-mediating compounds namely, 1-hydrozybenzotriazole (HBT), N-hydroxyphthalimide (HPI), 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO), violuric acid (VA), syringaldehyde (SA), vanillin (VA), and 2,2¡¬-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), which follow distinct oxidation pathways, for the degradation of trace organic contaminants (TrOCs). These redox-mediators were investigated for improved degradation of four TrOCs showing resistance to degradation by crude laccase from the white-rot fungus Pleurotus ostreatus. ABTS and VA achieved the highest degradation of the phenolic compounds (i.e., oxybenzone and pentachlorophenol), whereas the non-phenolic compounds (i.e., naproxen and atrazine) were best removed using VA or HBT. This implies that the non-phenolic compounds are more effectively removed by the radical species generated by the [Formula presented] type mediators (i.e., VA and HBT), while removal of the phenolic compounds may depend more on the stability and the redox potential of the radicals generated from the mediator, irrespective of the type. Notably, enzyme stability was greatly affected by the [Formula presented] type mediators but it was compensated by their rapid degradation capacity. Overall, VA and HBT ([Formula presented] type) appear to be the best mediators for enhanced degradation of the selected compounds without causing significant toxicity in the effluent. ? 2016
Subjects
Effluent toxicity
Laccase degradation
Redox mediator
Trace organic contaminant
Type
journal article