2,4-Dichlorophenol removal by purified horseradish peroxidase enzyme and crude extract from horseradish immobilized to nano spray dried ethyl cellulose particles

Abstract

Horseradish peroxidase (HRP) is a promising catalyst in the enzymatic process of phenolic compounds removal from wastewaters. Enzyme immobilization provides important benefits in a biotechnological process. Fine particles with a high surface-to-volume ratio composed of ethyl cellulose (EC) polymer were generated by Nano Spray Dryer B-90 as supports for HRP. Carrier particles were prepared by spray caps with hole size of 7μm, 5.5μm and 4μm. Purified HRP and crude extract from horseradish were covalently bound to the carrier using a carbodiimide cross-linker. The attached HRP content, the effect of pH on the activity and the storage stability were investigated. 2,4-dichlorophenol, an extremely persistent chlorinated phenol was removed by the immobilized enzyme, and the effect of main process parameters such as H2O2 and 2,4-dichlorophenol substrate concentrations were studied. After immobilization both the purified HRP and the horseradish extract performed better in the pH range of 4–10 and could preserve the activity substantially longer than the free enzyme. The immobilized enzyme was found to be outstandingly efficient (in optimal case close to 100%) in the elimination of 2,4-dichlorophenol, which was also the consequence of the high adsorbing capacity of the fine particles. The reuse study proved the operational stability of HRP attached to EC even after 10 consecutive cycles.