Effect of additives on enzyme-catalyzed polymerization of phenols and aromatic amines

Among biological approaches to the removal of aromatic amines and phenols from wastewater, the socalled enzyme-catalyzed polymerization and precipitation (ECPP) process relies on the use of oxidoreductases acting via radical mechanisms and characterized by a rather relaxed substrate specificity, such as laccase, tyrosinase and heme-peroxidases. The main technical constraints of ECPP processes are due to a variety of enzyme deactivation phenomena occurring during catalysis and to the incomplete removal of oxidation products from solution. In order to put ECPP into practice, these drawbacks have to be either counteracted or minimized. Although several approaches, such as enzyme immobilization and reaction engineering, have been proposed to limit these constraints, this review is intended to provide a wide survey on some chemical additives with either protective or coagulating effects that have been so far employed for these purposes.