Reshaping environmental sustainability: Poultry by-products digestate valorization for enhanced biochar performance in methylene blue removal

Ayoub Chaoui; Salaheddine Farsad; Aboubakr Ben Hamou; Asma Amjlef; Nisrine Nouj; Mohamed Ezzahery; Noureddine El Alem

doi:10.1016/j.jenvman.2023.119870

Reshaping environmental sustainability: Poultry by-products digestate valorization for enhanced biochar performance in methylene blue removal

J Environ Manage. 2024 Feb:351:119870. doi: 10.1016/j.jenvman.2023.119870. Epub 2023 Dec 22.

Authors

Ayoub Chaoui¹, Salaheddine Farsad², Aboubakr Ben Hamou², Asma Amjlef², Nisrine Nouj², Mohamed Ezzahery², Noureddine El Alem²

Affiliations

¹ Laboratory of Materials and Environment, Faculty of Sciences, Ibnou Zohr University, Agadir, Morocco. Electronic address: ayoub.chaoui@edu.uiz.ac.ma.
² Laboratory of Materials and Environment, Faculty of Sciences, Ibnou Zohr University, Agadir, Morocco.

PMID: 38141348
DOI: 10.1016/j.jenvman.2023.119870

Abstract

Anaerobic digestion is a highly effective and innovative method for treating organic waste while simultaneously generating energy. However, the treatment of the resulting digestate remains a challenging endeavor. To address this issue, poultry by-products digestate is used in this study to prepare biochars at two different pyrolysis temperatures (500/600 °C). Despite their potential, the utilization of untreated biochar is restricted due to its inadequate adsorption capacity. Therefore, each biochar was chemically activated using either HNO₃ or KOH to synthesize four activated biochars (BC5@KOH, BC6@HNO₃, BC5@HNO₃, and BC6@HNO₃). The aim is to investigate how the nature of chemical activation and pyrolysis temperature influence the adsorption of methylene blue dye. Characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), Raman analysis, and pHpzc determination, were exploited to comprehensively elucidate the structure and composition of both unprocessed and chemically activated biochars. Among the activated biochars, the adsorbent BC5@HNO₃ exhibits the highest methylene blue (MB) adsorption capacity, reaching 101.72 mg.g^-1 at 298 K under (pH = 2, ads dose = 0.6 g.L^-1, shaking time of 20 min, as optimal conditions for MB adsorption. Adsorption data for each adsorbent strongly aligns with both the Langmuir isotherm model and the pseudo-second-order kinetic model. Moreover, the thermodynamic study reveals that the adsorption process was endothermic and spontaneous. The adsorption mechanism of MB dye was explored using various analytical techniques, including FTIR, SEM, PZC, and pH impact assessment. The findings suggest correlations with electrostatic interactions, hydrogen bonding, pore filling, as well as n-π and π-π interactions. Apparently, activated biochars play a crucial role in efficiently removing methylene blue dye, showcasing their potential as environmentally friendly and effective adsorbents.

Keywords: Activated biochar; Activation; Adsorption; Biochar; Cationic dyes; Methylene blue.

MeSH terms

Adsorption
Animals
Charcoal / chemistry
Hydrogen-Ion Concentration
Kinetics
Methylene Blue* / chemistry
Poultry
Spectroscopy, Fourier Transform Infrared
Thermodynamics
Water Pollutants, Chemical* / chemistry

Substances

biochar
Methylene Blue
Water Pollutants, Chemical
Charcoal