title: Adsorption of metribuzin from aqueous solution using magnetic and nonmagnetic sustainable low-cost biochar adsorbents.
abstract: Switchgrass biochar (SGB) was made by fast pyrolysis in an auger-fed reactor at 425 °C with a solid residence time of 60 s in the pyrolysis zone during bio-oil production. Magnetic switchgrass biochar (MSGB) was prepared by iron oxide precipitation onto the biochar surface using an aqueous Fe3+/Fe2+solution followed by NaOH treatment. Both the SGB and the MSGB were characterized by FTIR, SEM, SEM-EDX, TGA, pHpzc, elemental analysis, and surface area measurements. Batch sorption studies of metribuzin from aqueous solutions were carried out at different pH values, adsorbate concentrations, and temperatures. The adsorption of metribuzin onto both biochars was highest at a pH of 2. Adsorption isotherms were evaluated from 25 to 45 °C using the Freundlich, Langmuir, Redlich-Peterson, Toth, Sips, Koble-Corrigan, and Radke-Prausnitz adsorption models. Langmuir adsorption capacities at pH 2 were Q0SGB~ 151, 223, and 205 mg/g and Q0MSGB~ 155, 205, and 155 mg/g at 25, 35, and 45 °C, respectively. Low-cost magnetization of the biochar occurred without significant loss of absorption capacity, enabling facile separation of slurried biochar from liquids following contaminate absorption. Graphical abstract ᅟ.
authors.affiliation: Department of Chemistry, Mississippi State University, Box 9573, Mississippi State, MS, 39762-9573, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Essandoh
authors.affiliation: Department of Chemistry, Mississippi State University, Box 9573, Mississippi State, MS, 39762-9573, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wolgemuth
authors.affiliation: Department of Chemistry, Mississippi State University, Box 9573, Mississippi State, MS, 39762-9573, USA.
authors.forename: Charles U
authors.initials: CU
authors.lastname: Pittman
authors.affiliation: School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Mohan
authors.affiliation: Department of Chemistry, Mississippi State University, Box 9573, Mississippi State, MS, 39762-9573, USA. TMlsna@chemistry.msstate.edu.
authors.forename: Todd
authors.initials: T
authors.lastname: Mlsna
mesh_terms: D000327:Adsorption; D002606:Charcoal / Q000737:chemistry* / Q000191:economics; D008280:Magnetics; D013696:Temperature; D014227:Triazines / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D014227:Triazines; D014874:Water Pollutants, Chemical; C540010:biochar; D002606:Charcoal; C009235:metribuzin
keywords: Adsorbent characterization; Adsorption; Isotherms; Low-cost adsorbent; Magnetic biochar; Metribuzin; Phenoxy herbicides; Solution pH