Abstract Enzymatic treatment systems play a significant role in the removal of phenolic pollutants from water, and naturally occurring clay minerals such as Turkish Green Clay (TGC) offer effective and environmentally friendly support materials for enzyme immobilization. In this study, polyphenol oxidase (PPO) was partially purified 10.70-fold with a yield of 15.21% from the zeferan peach ( Prunus persica L.) cultivar using the cold acetone precipitation method. Enzyme was immobilized onto TGC, and immobilization was confirmed by scanning electron microscopy (SEM). The immobilization yield was calculated as 37.26% based on activity measurements before and after immobilization. Both free and immobilized PPO exhibited an optimum pH of 7.0 and an optimum temperature of 30 °C. Kinetic analysis revealed K m and V max values of 2.13 mM and 1250.00 EU.mL −1 .min −1 . for the free enzyme and 1.0 mM and 1111.11 EU.mL −1 .min −1 . for the immobilized enzyme, indicating an increased affinity toward 4-methylcatechol upon immobilization. The immobilized enzyme exhibited superior thermal and pH stability compared to the free enzyme. Storage stability was evaluated at 4 °C for 15 days by measuring residual activity at 24-h intervals. After 15 days, the immobilized enzyme retained 69.75% of its initial activity, whereas the free enzyme maintained only 23.41% of its original activity. To assess the potential of the immobilized polyphenol oxidase for water treatment applications, phenol solutions at concentrations of 4, 8, 15, and 20 mg/mL were prepared and subjected to removal studies. The immobilized PPO eliminated phenol by 95.14%, 47.95%, 18.01%, and 11.7%, respectively. These results demonstrate that the immobilized enzyme is highly effective at removing phenol, particularly at low concentrations, and highlight its promise as an environmentally friendly biocatalyst for the treatment of phenol-contaminated water.
Kaya et al. (Wed,) studied this question.