Effect of environmental factors on laccase-mediated 17β-estradiol coupling reaction

Hazardous 17β-estradiol (E2) with a higher estrogen effect, has attracted the attention of many scholars. How to transform and remove E2 in the environment becomes a research hotspot. This paper systematically explores the impacts of environmental elements like temperature, pH value, laccase concentration, humic acid concentration, and the type and concentration of metal ions on the laccase-catalyzed oxidation process of E2. The results show that the optimal environmental conditions for laccase-catalyzed oxidation of E2 are temperatures of 25 °C to 30 °C, pH values of 4 to 5, laccase concentration of 30 unit·L^-1, no addition of humic acid, and the addition of Cu²⁺ at a density of 1 mmol·L^-1. The conversion rate of E2 by laccase remained above 70%. The coupling products were formed through covalent coupling mechanisms mediated by functional groups such as C-C and C-O-C, with the main product being E2 dimers. E2 underwent chain extension polymerization during the reaction. Laccase has the potential to remediate E2 contaminated environment in a green and efficient manner.