Mechanisms of antimony adsorption onto soybean stover-derived biochar in aqueous solutions

Meththika Vithanage, Anushka Upamali Rajapaksha, Mahtab Ahmad, Minori Uchimiya, Xiaomin Dou, Daniel S. Alessi, Yong Sik Ok

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

Limited mechanistic knowledge is available on the interaction of biochar with trace elements (Sb and As) that exist predominantly as oxoanions. Soybean stover biochars were produced at 300°C (SBC300) and 700°C (SBC700), and characterized by BET, Boehm titration, FT-IR, NMR and Raman spectroscopy. Bound protons were quantified by potentiometric titration, and two acidic sites were used to model biochar by the surface complexation modeling based on Boehm titration and NMR observations. The zero point of charge was observed at pH 7.20 and 7.75 for SBC300 and SBC700, respectively. Neither antimonate (Sb(V)) nor antimonite (Sb(III)) showed ionic strength dependency (0.1, 0.01 and 0.001M NaNO3), indicating inner sphere complexation. Greater adsorption of Sb(III) and Sb(V) was observed for SBC300 having higher -OH content than SBC700. Sb(III) removal (85%) was greater than Sb(V) removal (68%). Maximum adsorption density for Sb(III) was calculated as 1.88×10-6molm-2. The Triple Layer Model (TLM) successfully described surface complexation of Sb onto soybean stover-derived biochar at pH 4-9, and suggested the formation of monodentate mononuclear and binuclear complexes. Spectroscopic investigations by Raman, FT-IR and XPS further confirmed strong chemisorptive binding of Sb to biochar surfaces.

Original languageEnglish
Pages (from-to)443-449
Number of pages7
JournalJournal of Environmental Management
Volume151
DOIs
Publication statusPublished - 2015 Mar 5
Externally publishedYes

Keywords

  • Black carbon
  • Charcoal
  • Slow pyrolysis
  • Surface charge
  • Surface complexation model

ASJC Scopus subject areas

  • Environmental Engineering
  • Waste Management and Disposal
  • Management, Monitoring, Policy and Law

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