Sustainable valorization of protein-rich tannery saline wastewater: Protein hydrolysate synthesis via protease and Fe3O4 porous carbon catalyst

Abstract

The objective of the current study is to produce valuable protein hydrolysates (PHs) by fragmenting the proteins in protein-rich tannery wastewater (TANWWpro) through a protease-immobilized nanoporous carbon catalyst (PNPCC). The protease was isolated from the microorganism Lysinibacillus fusiformis MR1 and it contains 385 U/mL of proteolytic activity. For the immobilization of protease onto PNPCC, the ideal conditions were 2 h, pH 6–8, and 30–40 °C. FTIR, TGA, DSC, and XRD analyses were used to evaluate the protease immobilization on AGF-NPCC. For protein fragmentation, the appropriate pH, which was determined at 6, the ideal duration and temperature of 120 min at 30 °C as well as the required quantity of PNPCC were optimized. HPLC-free amino acid analysis has been used to validate the generation of PHs from TANWWpro, while electroanalytical methods including impedance spectroscopy and cyclic voltammetry have been used to establish their varied redox characteristics. Furthermore, PHs were extracted by using a Fe3O4- impregnated nanoporous carbon catalyst (Fe3O4-NPCC) and the SEM images verified the impregnation of Fe3O4 onto NPCC. Overall, employing the PNPCC and Fe3O4-NPCC, the generation and extraction of PHs from TANWWpro were both performed effectively.