Reduction and Adsorption of Hexavalent Chromium by Iron Sulfide Loaded Biochar: Isotherms, Kinetics and Thermodynamics

Mpho Cynthia Qhubu, Mahadi Lesaoana, Philiswa Nosizo Nomngongo, Vusumzi Emmanuel Pakade

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The removal of noxious Cr(VI) from water has gained worldwide attention. In this study, biochar derived from macadamia nut shells (MHP) was embedded with iron sulfide (FeS) nanoparticles produced through a solid-phase reduction of pyrite. The MHP-FeS composite was evaluated for the adsorption of Cr(VI) and its subsequent reduction to Cr(III). The scanning electron microscope images revealed that the particles were of irregular shape, while the energy dispersive spectroscopy results showed the existence of Fe, S, O, and C atoms. X-ray diffraction peaks at 2=29.8°, 33.7°, 43.7°, and 53.1° were characteristic of the formation of FeS nanoparticles. A maximum Cr(VI) adsorption capacity of 4.95 mg/g was obtained at pH 3, 60 min, and 25 °C. The higher correlation coefficient (R2>0.873) and lower residual standard error (RSE=1.43) values pointed to the adsorption process favoring Langmuir and pseudo-second-order models. As per thermodynamic reaction calculations, the remediation process was spontaneous and endothermic. With further optimization, this material could be a potential adsorbent and reductant for Cr(VI) in water.

Original languageEnglish
Article numbere202301170
JournalChemistrySelect
Volume8
Issue number32
DOIs
Publication statusPublished - 31 Aug 2023

Keywords

  • Adsorption
  • Biochar
  • Chromium
  • Iron sulfide
  • Reduction

ASJC Scopus subject areas

  • General Chemistry

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