An environmentally-friendly enzyme-based nanofibrous membrane for 3,3′,5,5′-tetrabromobisphenol removal

Chitosan (CS)/poly(vinyl alcohol) (PVA) nanofibrous membranes have inherently poor mechanical strength. To improve the mechanical strength of these membranes, nanocrystalline cellulose (NCC) prepared by a simplified method was added to the former system. The results showed that the tensile strength of the membrane with 5% NCC addition was 370% higher than that of the membrane without NCC. Horseradish peroxidase (HRP) was immobilized on the membrane through covalent binding with HRP previously activated with 1,1′-carbonyldiimidazole, and the maximum enzyme loading was approximately 384 mg g^-1. The physical, chemical properties of immobilized HRP and its application in 3,3′,5,5′-tetrabromobisphenol (TBBPA) removal were examined. The results showed that HRP immobilized on CS/PVA-NCC membranes showed greater stability and reusability than free HRP and the membrane without NCC. The former also exhibited an effective performance (95.9% removal, 3 h) for TBBPA removal under the optimum conditions (pH 7, 35 °C). The results showed that HRP immobilized on NCC-incorporated CS/PVA membranes could be used to remove brominated flame-retardants, especially TBBPA from wastewater. Thus, these membranes have potential industrial applications.