Synthesis of peroxidase-encapsulated sodium cellulose sulphate/poly-dimethyl-diallyl-ammonium chloride biopolymer via polyelectrolyte complexation for enhanced removal of phenol

Abstract

Peroxidases have attracted significant interests in enzymatic wastewater treatment strategies. In this work, jicama peroxidase (JP) was extracted from jicama skin peels and used for the degradation of phenol under free and immobilized conditions. The crude enzyme extract demonstrated enzymatic activity of 1.6 ± 0.1 U mL−1. Sodium cellulose sulphate/poly-dimethyl-diallyl-ammonium chloride (NaCS-PDMDAAC) spherical capsules were synthesized and immobilized with crude JP to generate JP beaded capsules with an average diameter of 5.05 mm ± 0.16 mm. Phenol biodegradation analysis showed that the free and immobilized JP capsules demonstrated optimum working pH values of 7 and 6, respectively, and both systems maintained JP catalytic functionalities over a broad range of H2O2 concentration before H2O2 inhibition. The optimal temperature range for phenol removal was from 25°C to 40°C for both free and immobilized JP with lower removal efficiency above 45°C due to thermal denaturation. Due to diffusive mass transfer limitation, immobilized JP capsules required a longer reaction time of 15 hr for optimal phenol removal efficiency of >95%, whereas free JP achieved the same efficiency in 13 hr. The first order kinetic rate constants for free and immobilized JP capsules were determined to be 1.21 hr−1 and 1.02 hr−1, respectively. JP capsules maintained reusability up to 4 cycles at the highest removal efficiency of >95% with no regeneration.