Insights into simultaneous adsorption and oxidation of antimonite [Sb(III)] by crawfish shell-derived biochar: spectroscopic investigation and theoretical calculations

Hanbo Chen, Yurong Gao, Jianhong Li, Chenghua Sun, Binoy Sarkar, Amit Bhatnagar, Nanthi Bolan, Xing Yang, Jun Meng, Zhongzhen Liu, Hong Hou, Jonathan W.C. Wong, Deyi Hou, Wenfu Chen, Hailong Wang*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

21 Citations (Scopus)

Abstract

Removal of antimonite [Sb(III)] from the aquatic environment and reducing its biotoxicity is urgently needed to safeguard environmental and human health. Herein, crawfish shell-derived biochars (CSB), pyrolyzed at 350, 500, and 650°C, were used to remediate Sb(III) in aqueous solutions. The adsorption data best fitted to the pseudo-second-order kinetic and Langmuir isotherm models. Biochar produced at 350°C (CSB350) showed the highest adsorption capacity (27.7 mg g− 1), and the maximum 78% oxidative conversion of Sb(III) to Sb(V). The adsorption results complemented with infrared (FTIR), X-ray photoelectron (XPS), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy analyses indicated that the adsorption of Sb(III) on CSB involved electrostatic interaction, surface complexation with oxygen-containing functional groups (C = O, O = C–O), π–π coordination with aromatic C = C and C–H groups, and H-bonding with –OH group. Density functional theory calculations verified that surface complexation was the most dominant adsorption mechanism, whilst π–π coordination and H-bonding played a secondary role. Furthermore, electron spin resonance (ESR) and mediated electrochemical reduction/oxidation (MER/MEO) analyses confirmed that Sb(III) oxidation at the biochar surface was governed by persistent free radicals (PFRs) (•O2 and •OH) and the electron donating/accepting capacity (EDC/EAC) of biochar. The abundance of preferable surface functional groups, high concentration of PFRs, and high EDC conferred CSB350 the property of an optimal adsorbent/oxidant for Sb(III) removal from water. The encouraging results of this study call for future trials to apply suitable biochar for removing Sb(III) from wastewater at pilot scale and optimize the process.

Original languageEnglish
Article number37
Number of pages16
JournalBiochar
Volume4
Issue number1
Early online date4 Jul 2022
DOIs
Publication statusPublished - Dec 2022

Scopus Subject Areas

  • Biomaterials
  • Environmental Science (miscellaneous)
  • Soil Science
  • Pollution

User-Defined Keywords

  • Contaminated water
  • Density functional theory
  • Heavy metal
  • Sorption
  • Synchrotron

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