Cross-linked carbon nanotubes-based biocatalytic membranes for micro-pollutants degradation: Performance, stability, and regeneration

The presence of the micro-pollutants in the aqueous environment has become a major environmental challenge. The enzymatic membrane reactor (EMR) provides a promising approach to tackle this problem through benign enzymatic biodegradation, and the fabrication of highly efficient enzymatic membrane is the key to this process. By using a facile carbon nanotube (CNTs) coating technique, we prepared a stable CNTs coating on a polymer membrane support, which was then applied for laccase immobilization via both physical adsorption and covalent bonding. The biocatalytic membrane possessed stability for long-term storage and under hydraulic shear force. Micro-pollutant degradation was carried out with a mixture of five representative compounds (bisphenol-A (BPA), carbamazepine (CBZ), diclofenac (DCF), clofibric acid (CA) and ibuprofen (IBF)). The EMR exhibited substantial improvement in micro-pollutant removals compared with the CNTs-coated membrane having no enzytrte. Furthermore, the effects of CNTs loading and operational flux on the EMR performance were examined, and the stability of the enzymatic membranes was studied. Active laccase coatings on CNTs-coated membrane could be renewed after simple cleaning and re-coating, offering new opportunities towards sustainable, long-term applications. (C) 2016 Elsevier B.V. All rights reserved.