Phenol Removal from Wastewater Using Tyrosinase Enzyme Immobilized in Granular Activated Carbon and Activated Chitosan Beads

Abstract

Tyrosinase enzyme in a crude extract was immobilized in granular activated carbon (GAC) and activated chitosan beads (ACBs), two low-cost supports. It was possible to immobilize up to 70% of the enzymes in GAC under the conditions of 20 g/L support, stirring of 15.7 rad/s, contact time of 120 min, and up to 100% of enzymes in ACBs under the same conditions. In enzymatic oxidation tests, tyrosinase immobilized in GAC (T-GAC) was able to achieve a final phenol concentration below the limit required by the Brazilian legislation (0.5 mg/L) for solutions with initial concentrations of 10 mg/L, while the enzyme immobilized in ACBs (T-ACBs) was able to conform solutions with initial concentrations of phenol of 40 mg/L. It was possible to reuse the T-GAC two times, maintaining the same phenol removal efficiency, while the T-ACBs maintained up to 98% of its efficiency after five cycles of enzymatic oxidation of solutions of 10 mg/L phenol. It was possible to achieve the same phenol removal efficiency, with immobilized enzymes stored for up to 2 weeks. Such results suggest that both materials are effective for phenol removal from water samples, especially T-ACBs, representing promising alternatives for mitigating the effects of this compound in industrial wastewater.