A novel protease-immobilized carbon catalyst for the effective fragmentation of proteins in high-TDS wastewater generated in tanneries: Spectral and electrochemical studies

Environ Res. 2019 May:172:408-419. doi: 10.1016/j.envres.2019.01.062. Epub 2019 Feb 20.

Abstract

The aim of this study was to degrade proteins in high-total dissolved solids (TDS)-containing wastewater produced during the soaking process in tanneries (tannery-TDS wastewater) using a halotolerant protease-assisted nanoporous carbon catalyst (STPNPAC). A halotolerant protease was obtained from the halophile, Lysinibacillus macroides, using animal fleshing as the substrate. The protease was immobilized using ethylene diamine (EDA)/glutaraldehyde functionalized nanoporous activated carbon (EGNPAC). The optimum conditions for the immobilization of protease were determined as time (120 min), pH (6), protease concentration (575-600 U/g), EGNPAC size, salinity, and temperature (30 °C). The immobilization was confirmed by FTIR, TGA-DSC, SEM, and XRD analyses. The adsorption kinetics was consistent with a pseudo first order rate constant of 1.43 × 10-2 min-1. The thermodynamic parameters (ΔG, ΔH, and ΔS) confirmed the effective immobilization of the protease onto EGNPAC. STPNAPC was found to efficiently degrade the proteins in tannery-TDS wastewater, with a complete fragmentation time of 90 min at pH 6 and 30 °C. Accordingly, the protein fragmentation was confirmed by UV-visible and UV-fluorescence spectroscopy, ESI-mass spectrometric analysis and circular dichroic studies. The formation of protein hydrolysates was confirmed by cyclic voltammetry and electrical impedance studies. BOD5: COD value, 0.426 of treated tannery-TDS wastewater may favor sequential biological treatment processes.

Keywords: Immobilization; Lysinibacillus macroides; Nanoporous activated carbon; Protease; Protein hydrolysates; Tannery-TDS wastewater.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Animals
  • Carbon* / chemistry
  • Catalysis
  • Electrochemical Techniques
  • Industrial Waste
  • Kinetics
  • Peptide Hydrolases*
  • Spectrum Analysis
  • Thermodynamics
  • Wastewater* / chemistry
  • Water Purification* / methods

Substances

  • Industrial Waste
  • Waste Water
  • Carbon
  • Peptide Hydrolases