Preparation of activated carbon from discarded microbial petri dish plastic waste and its application in hydrolytic enzyme bioprocessing and activation

Abstract

Plastic waste is considered one of the biggest blockages to environmental sustainability due to its wide consumption and huge production as a solid waste worldwide. Recycling and valorizing plastic waste via the thermochemical route is a promising approach. In this work, we report the preparation of activated carbon (AC) based catalyst using lab-used, microbiologically discarded petri dish plates and characterized through XRD, FT-IR, BET, SEM, and TEM techniques. Further, a comparative application of this activated AC catalyst has been studied in enzyme production through solid-state fermentation using open aerobic microbial culture (OAC) and a lab-isolated fungal culture Rhizopus oryzae NS5 (RO). Cellulase enzyme production with filter paper activity (FPA) of 28 IU/gds and 25 IU/gds FPA were noticed on day three of microbial fermentation using 0.5 mg AC catalyst in the case of OAC and RO systems, respectively. The crude cellulase enzyme obtained from OAC using 1 mg concentration in SSF reflected thermal stability at 50 °C and 60 °C, showing 42 % and 36 % of relative enzyme activity, along with 58 % of relative activity at pH 5.0 for 20 h at 50 °C. The research could have promising implications for plastic waste management and enzyme bioprocessing for a variety of industrial uses.