title: Removal of p-alkylphenols from aqueous solutions by combined use of mushroom tyrosinase and chitosan beads.
abstract: Enzymatic removal of p-alkylphenols from aqueous solutions was investigated through the two-step approach, the quinone conversion of p-alkylphenols with mushroom tyrosinase (EC 1.14.18.1) and the subsequent adsorption of quinone derivatives enzymatically generated on chitosan beads at pH 7.0 and 45 degrees C as the optimum conditions. This technique is quite effective for removal of various p-alkylphenols from an aqueous solution. The % removal values of 97-100% were obtained for p-n-alkylphenols with carbon chain lengths of 5 to 9. In addition, removal of other p-alkylphenols was enhanced by increasing either the tyrosinase concentration or the amount of added chitosan beads, and their % removal values reached >93 except for 4-tert-pentylphenol. This technique was also applicable to remove 4-n-octylphenol (4NOP) and 4-n-nonylphenol (4NNP) as suspected endocrine disrupting chemicals. The reaction of quinone derivatives enzymatically generated with the chitosan's amino groups was confirmed by the appearance of peaks for UV-visible spectrum measurements of the chitosan films incubated in the p-alkylphenol and tyrosinase mixture solutions. In addition, 4-tert-pentylphenol underwent tyrosinase-catalyzed oxidation in the presence of hydrogen peroxide.
authors.affiliation: Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Japan. k5yamada@cit.nihon-u.ac.jp
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yamada
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Inoue
authors.forename: Yuji
authors.initials: Y
authors.lastname: Akiba
authors.forename: Ayumi
authors.initials: A
authors.lastname: Kashiwada
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Matsuda
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Hirata
mesh_terms: D000363:Agaricales / Q000201:enzymology*; D048271:Chitosan; D052244:Endocrine Disruptors / Q000378:metabolism; D004785:Environmental Pollutants / Q000378:metabolism; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010636:Phenols / Q000378:metabolism*; D012996:Solutions; D014867:Water; D018508:Water Purification / Q000379:methods*
chemical_list: D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D010636:Phenols; D012996:Solutions; D014867:Water; D048271:Chitosan; D014442:Monophenol Monooxygenase