Enzymatic Removal of Diclofenac and Aceclofenac from Water by Soybean Peroxidase

Pharmaceuticals are a class of emerging contaminants that have been widely detected in wastewater treatment facilities' influent and effluent. They threaten the environment and non-target life. Thus, a promising treatment method, soybean peroxidase (SBP; EC 1.11.1.7), which catalyzes the oxidation of phenolic and anilino donors in the presence of hydrogen peroxide, was investigated as a treatment method. The aim was to remove two non-steroidal anti-inflammatory drugs, diclofenac (DCF) and aceclofenac (ACF), from synthetic wastewater via enzymatic oxidation, oligomerization, and precipitation. SBP can be extracted from soybean hulls, a byproduct of the soybean industry. DCF (0.10 mM) and ACF (0.10 mM) were amenable to SBP-catalyzed removal under the optimal operational parameters of pH 5 and 4; hydrogen peroxide: 0.40 and 0.45 mM; and minimum effective enzyme concentration: 0.15 and 0.60 U/mL, respectively. The initial first-order rate constant and half-life of each substrate were also determined under the established optimum conditions. Under these optimum conditions, the half-lives for DCF and ACF were 1.43 ± 0.01 and 0.84 ± 0.05 min, respectively. The results demonstrated that SBP is a robust enzyme that can achieve more than 95% removal for both compounds. Mass spectrometric analysis of the enzymatic treatment products of DCF revealed the formation of an oxidative tetramer. The SBP-catalyzed reaction is a highly effective method for removing DCF and ACF from synthetic wastewater, highlighting its potential for environmental cleanup of pharmaceutical contaminants.