Peroxidase Conjugate of Cellulose Nanocrystals for the Removal of Chlorinated Phenolic Compounds in Aqueous Solution

The study was conducted to immobilize peroxidase (E.C. 1.11.1.7) on to the rodlike cellulose nanocrystals after activation with cyanogen bromide treatment. The resulted bioactive conjugates were used to remove chlorinated phenolic compounds in aqueous solution. Gas phase Fourier transfer infrared spectroscopy was used for the detection and quantification of ammonia released from the immobilization reactions in situ. Results revealed that cyanogen bromide treatment of cellulose nanocrystals generated cyclic imidocarbonate group and cellulose carbamate. Covalent bonding between the activated nanoparticles and peroxidase generated ammonia as one of byproducts and the ammonia generation at an elevated temperature was more significant. Immobilization of enzyme at room temperature resulted in the bioactive conjugates with enzyme activity of 594 unit g super(-1). Increase of immobilization temperature to 50 degree C led to thermal deactivation of enzyme although immobilization probably proceeded fast. Comparing to its soluble counterpart, the immobilized peroxidase demonstrated high removal of chlorinated phenolic compounds. This capability might be attributed to the stabilization effect of immobilization toward enzyme deactivation and the precipitate formation of oxidized phenol products inducing by the amino group from carbamate on the bioactive conjugates.