Enzymatic Decolourization of Water Using Loofa Sponge as Cellular Carrier: Immobilization and Dye Degradation Performance

In recent years, strong efforts have been made to develop sustainable biocatalytic decolorization processes for dye-polluted water. In particular, dye-oxidizing laccase enzymes immobilized on suitable carriers are promising candidates, which can be reused as long as the activity is sufficiently high.
In this work, we propose, for the first time, a new methodology to immobilize laccase from Trametes hirsute on natural-grown and decomposable cellular loofa sponge carrier and assess the capability to degrade dye-polluted water. High immobilization activity is achieved and about 70 % residual activity remains after 8 cycles. Additionally, we determined homogenous and heterogeneous kinetic parameters for free and immobilized enzymes. Results reveal four times higher Michaelis-Menten constant of the laccase immobilized on loofa due to mass transfer and mixing limitations in packed bed bio-reactor.
Eventually, the response surface methodology was applied to identify favorable operation condition in terms of dye concentration, treatment time and mixing velocity. Here, the results demonstrated a remarkable dye removal capability with shorter treatment time compared to the previous studies on immobilized laccase reported in the literature.