The role of ultrasound in enzymatic degradation mechanism

Abstract

Abstract In this study, an attempt was made to investigate the mechanistic insight to identify the links between enzymatic and sonolysis processes through degradation mechanism. Experimental results revealed that ultrasound and cavitation increase the number of collision in enzymatic process through intense convection in the medium generated by transient cavitation, and enhances degradation efficiency by increasing interaction between enzyme and organic molecules. The formation of pH· radicals in Bisphenol-A degradation is significant and it needs external binding agent such as polyethylene glycol (PEG) to prevent the blocking of reactive sites of enzymes. On the other hand, Ciprofloxacin is susceptible to enzyme, and thus the degradation enhancement is not much significant in sono-enzymatic process. The highest degradation rates at optimum condition of pH 7.0 and 25 °C were 66.52% and 68.41% for Bisphenol-A and Ciprofloxacin, respectively. The antimicrobial activity test and the LCMS results revealed that the intermediates (acetic acid, ethyl alcohol and other products with –OH group) formed during sono-enzymatic reaction are less toxic as compared to that formed in enzymatic process. This essentially means that the enzymatic process initiates the degradation reaction and ultrasound helps towards complete mineralization by degrading the intermediates. To the best of our knowledge, this is the first report on detailed degradation mechanism of Bisphenol-A and Ciprofloxacin using enzymatic and sono-enzymatic processes.