title: Mechanisms of antimony adsorption onto soybean stover-derived biochar in aqueous solutions.
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 0.001 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.
authors.affiliation: Korea Biochar Research Center, Kangwon National University, Chuncheon 200-701, Republic of Korea; Chemical and Environmental Systems Modeling Research Group, Institute of Fundamental Studies, Kandy, Sri Lanka. Electronic address: meththikavithanage@gmail.com.
authors.forename: Meththika
authors.initials: M
authors.lastname: Vithanage
authors.affiliation: Korea Biochar Research Center, Kangwon National University, Chuncheon 200-701, Republic of Korea; Chemical and Environmental Systems Modeling Research Group, Institute of Fundamental Studies, Kandy, Sri Lanka. Electronic address: anushkaupamali@gmail.com.
authors.forename: Anushka Upamali
authors.initials: AU
authors.lastname: Rajapaksha
authors.affiliation: Soil Sciences Department, College of Food & Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia. Electronic address: mah_tabee@yahoo.com.
authors.forename: Mahtab
authors.initials: M
authors.lastname: Ahmad
authors.affiliation: Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124, United States. Electronic address: Sophie.Uchimiya@ARS.USDA.GOV.
authors.forename: Minori
authors.initials: M
authors.lastname: Uchimiya
authors.affiliation: College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Dou
authors.affiliation: Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada. Electronic address: alessi@ualberta.ca.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Alessi
authors.affiliation: Korea Biochar Research Center, Kangwon National University, Chuncheon 200-701, Republic of Korea. Electronic address: soilok@kangwon.ac.kr.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
mesh_terms: D000327:Adsorption; D000965:Antimony / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D009994:Osmolar Concentration; D012989:Soil Pollutants / Q000737:chemistry*; D013025:Glycine max; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D012989:Soil Pollutants; C540010:biochar; D002606:Charcoal; D000965:Antimony
keywords: Black carbon; Charcoal; Slow pyrolysis; Surface charge; Surface complexation model