Covalent Immobilization of Laccase onto Nanofibrous Membrane for Degradation of Pharmaceutical Residues in Water

Abstract

Enzymatic degradation with ligninolytic enzyme e.g. laccase is a potential green solution for removal of pharmaceutical compounds that are released into the environment through wastewater effluent. However, the deficiencies of using the enzyme in its free forms, such as reusability and stability should be addressed before industrial applications. In this study, laccase was immobilized onto tailor-made Polyacrylonitrile-biochar composite nanofibrous membrane through covalent bonding and the parameters of immobilization were optimized. The obtained biocatalyst was utilized for removal of chlortetracycline (CTC), carbamazepine (CBZ) and diclofenac (DCF) at an environmentally-relevant concentration in batch mode. These pharmaceutical compounds represented three main categories of pharmaceutical compounds i.e. antibiotics, antidepressant, and anti-inflammatory. The results showed that the immobilized laccase has improved storage, temperature and pH stability compared to free laccase. Also, it maintained more than 17 % of its initial activity after 10 cycles of ABTS oxidation which indicated improved reusability of the enzyme. Using immobilized laccase for degradation of three pharmaceutical compounds in batch experiments exhibited 72.7%, 63.3% and 48.6% degradation efficiency for DCF, CTC, and CBZ, respectively after 8 hours of reaction. The decreasing trend of adsorption extent during reaction time for all compounds confirmed the regenerative effect of laccase on adsorption sites of biochar.

Enzymatic monolithic reactors for micropollutants degradation

“…For laccases it was shown that a covalent grafting via a crosslinking agent such as glutaraldehyde is very efficient. Immobilization support materials like ceramic mono or multichannel membranes [19,20], nano-fibrous membranes [21], metal nanoparticles [22], carbon nanotubes [23] and mesoporous materials [24], magnetic cross-linked enzyme aggregates (M-CLEAs) [25] have successfully demonstrated the immobilization of laccase for the degradation of antibiotics. However, many of these materials present a limited surface area available for grafting; this is especially the case of membranes.…”

Polymer supports for the removal and degradation of hazardous organic pollutants: an overview

“…reported the covalent immobilization of Trametes versicolor laccase on a nanofibrous membrane applied to the degradation of the pharmaceuticals diclofenac, chlortetracycline and carbamazepine. Degradation efficiencies of 72.7%, 63.3% and 48.6%, respectively, were obtained after 8 h of the reaction . These results demonstrate the great capacity for degradation presented by systems with immobilized enzymes.…”

“…Degradation efficiencies of 72.7%, 63.3% and 48.6%, respectively, were obtained after 8 h of the reaction. 118 These results demonstrate the great capacity for degradation presented by systems with immobilized enzymes. In addition, when comparing the degradation performed by the free enzyme with the immobilized enzyme, the immobilized enzyme was shown to work more efficiently and over a wider range of conditions.…”

Dioxygen Activation by Laccases: Green Chemistry for Fine Chemical Synthesis

“…It showed high oxidation potential (265% that of the free enzyme), and retained the residual enzyme efficiency of up to 84.6% under repeated batch conditions of 10 cycles [108] Chitosan crosslinked with genipin Improved pH, thermal, and storage stabilities of when compared with the free counterpart. The chitosan laccase system exhibited a residual activity of >55% after 11 cycles [109] polyacrylonitrile-biochar composite nanofibrous membrane High conversion for after 8 h of reaction [110] Table 3. Cont.…”