Application of fly ash adsorbed peroxidase for the removal of bisphenol A in batch process and continuous reactor: Assessment of genotoxicity of its product

In the present study peroxidase has been immobilized simply by adsorption on fly ash. On fly ash adsorbed nearly 1113 U of peroxidase activity per g. Comparative degradation of endocrine disrupter, bisphenol A has been performed by soluble and immobilized enzyme. Soluble and immobilized enzyme removed maximum bisphenol A in the presence of 0.3 mM guaiacol, a redox mediator, 0.75 mM H2O2 in sodium phosphate buffer, pH 7.0 at 40 °C. Degradation of bisphenol A in batch process was 61%, 100% and 100% at 20, 40 and 60 °C, respectively. Fly ash adsorbed peroxidase was more effective in the degradation of bisphenol A as compared to its free form. Immobilized enzyme catalyzed complete degradation of bisphenol A at 40 °C within 3.5 h. The oxidative degradation and polymerization of bisphenol A was also evaluated in the continuous bed-reactors at different flow rates. The removal of this compound was maximum at a flow rate of 20 mL h−1. HPLC analysis showed two clear peaks, one related to bisphenol A and other related to its degradation product, 4-isopropenylphenol. Plasmid nicking and comet assays demonstrated that the product, 4-isopropenylphenol was significantly nontoxic.