Immobilization of polyphenol oxidase on alginate–SiO 2 hybrid gel: stability and preliminary applications in the removal of aqueous phenol

An organic/inorganic hybrid gel of alginate–SiO 2 (ALG–SiO 2 ) was used to immobilize the partially purified potato polyphenol oxidase (PPO) for the treatment of phenolic wastewater. The influences of alginate concentration, quantity of both enzyme and tetramethoxysilane (TMOS) on immobilization were investigated. The Michaelis constant for immobilized PPO was determined as 14.7 mmol L −1 at 25 °C, and the highest activity of immobilized PPO was achieved at pH 7.0. The ALG–SiO 2 immobilized PPO was more stable than the free PPO or ALG(alone) immobilized PPO. This study suggests that ALG–SiO 2 immobilized PPO might be a potential tool for the removal of phenolic compounds from industrial wastewater.