Enhanced biocatalytic degradation of nevirapine in water with immobilised cross-linked laccase and tyrosinase embedded within a membrane

In this study a modified membrane comprising of two commercial enzymes i.e. laccase and tyrosinase were fabricated and applied for the removal of a model antiretroviral drug. The enzymes were immobilised as combined cross-linked laccase and tyrosinase (Combi-CLEA-Lac-Tyr) aggregates, using chitosan as a cross linking agent. In the Fourier transform infrared (FTIR) spectrum, a peak was observed at 1649 cm−1 (–CONH) confirming successful cross linking of Combi-CLEA-Lac-Tyr. The Combi-CLEA-Lac-Tyr was immobilised on a polyethersulfone (PES) membrane via the phase inversion method, with hyperbranched polyethyleneimine (HPEI) as an additive. The PES/HPEI/Combi-CLEA-Lac-Tyr demonstrated figure-like structures within the membrane matrix and had a hydrophilicity of up to 57.7°. The PES/HPEI/Combi-CLEA-Lac-Tyr membranes exhibited excellent removal efficiency (98.81 %) towards 5 mg/L nevirapine at pH 7. This was due to the synergetic effect of the Combi-CLEA-Lac-Tyr and the HPEI present within the membrane matrix.