Use of chitosan for removal of naphthols through tyrosinase‐catalyzed quinone oxidation

Abstract

AbstractIn this study, the combined use of chitosan and mushroom tyrosinase was applied to remove 1‐naphthol and 2‐naphthol from aqueous solutions. In particular, the process parameters, such as the pH value, temperature, and enzyme dose, were discussed for tyrosinase‐catalyzed quinone oxidation of 1‐naphthol. The optimum conditions of enzymatic quinone oxidation of 1‐naphthol were determined to be pH 8.0 and 40°C. Under the optimum conditions, quinone oxidation of 1‐naphthol increased with an increase in the enzyme dose. Quinone derivatives enzymatically generated were chemisorbed on chitosan bead sand. The initial velocity of enzymatic quinone oxidation increased with an increase in the amount of added chitosan beads, since unfavorable interactions between quinone derivatives and tyrosinase in the solutions were restrained by quinone adsorption. 1‐Naphthol was completely removed for 8 h by quinone adsorption on chitosan beads (0.10 cm3/cm3) at 20 U/cm3. The removal time was shortened by increasing the enzyme dose or the amount of added chitosan beads. 2‐Naphthol was also completely removed by increasing the enzyme concentration and reaction time, since enzymatic quinone oxidation of 2‐naphthol was much slower than that of 1‐naphthol. The above results reveal that the procedure constructed in this study was an effective technique to remove naphthols. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012