Synthesis of magnetically recyclable porous cross-linked aggregates of Tramates versicolor MTCC 138 laccase for the efficient removal of pentachlorophenol from aqueous solution.

The primary objective of this study is to synthesize the magnetically separable highly active porous immobilized laccase for the removal of pentachlorophenol (PCP) in an aqueous solution. Magnetic porous cross-linked enzyme aggregates (Mp-CLEAs) of laccase were synthesized using 1% starch solution with 5 mM glutaraldehyde followed by 10 h of cross-linking time with an activity recovery of 90.85 ± 0.2%. The biocatalytic efficiency of magnetic porous CLEAs (Mp-CLEAs) was 2-fold higher than that of magnetic CLEAs. The synthesized Mp-CLEAs were mechanically stable with enhanced catalytic efficiency, and reusability thus overcoming the mass transfer limitations and enzyme loss. At 40 °C, the thermal stability of the magnetic porous immobilized laccase was improved, with a 602 min half-life compared to 207 min half-life for the free enzyme. Using 40 U/mL of laccase for the removal of 100 ppm of PCP, M-CLEAs, and Mp-CLEAs removed 60.44% and 65.53% of PCP, respectively. Furthermore, to enhance PCP removal, a laccase-aided system was harnessed by optimizing various surfactants and mediators. Of these, 0.1 mM of rhamnolipid and 2,3 dimethoxy phenol had the highest PCP removal rates of 95.12% and 99.41%, respectively, for Mp-CLEAs. This study demonstrates the efficacy of the laccase-surfactant-mediator system for the removal of PCP from the aqueous solution, which can also be proposed for real-time application.