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

TitleMechanisms of antimony adsorption onto soybean stover-derived biochar in aqueous solutions
Publication TypeJournal Article
Year of Publication2015
AuthorsVithanage, Meththika, Rajapaksha Anushka Upamali, Ahmad Mahtab, Uchimiya Minori, Dou Xiaomin, ALESSI Daniel S., and Ok Yong Sik
JournalJournal of Environmental Management
Pagination443 - 449
Date Published03/2015

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 0.001 M 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 × 10−6 mol m−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.

Short TitleJournal of Environmental Management