Phenoxy herbicide removal from aqueous solutions using fast pyrolysis switchgrass biochar.
The release of herbicides is known to negatively impact humans and the environment. We report the use of a low cost biochar (prepared through fast pyrolysis) to successfully remove phenoxy herbicides from aqueous solutions. The biochar was characterized using: FT-IR, SEM, pHpzc, elemental analysis, and surface area measurements. Sorption experiments were run at pH values from 2 to 10, adsorbate concentrations from 25 to 300 mg/L and temperatures from 25 to 45 °C. Adsorption isotherms were evaluated from 25 to 45 °C using both two parameter (Freundlich and Langmuir) and three parameter (Redlich-Peterson and Toth) adsorption isotherm models. The maximum adsorption capacities for 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) were Q0SGB∼134 mg/g and Q0SGB∼50 mg/g, respectively, at pH 2. This low surface area switchgrass biochar (1.1 m2/g) can adsorb far more MCPA per unit of measured surface area (45 mg/m2) than high surface area commercial activated carbons (1050-1150 m2/g) which absorb only 0.08-0.11 mg/m2, and are also expensive. This indicates that biochar three dimensional swelling occurs in an aqueous environment and adsorbates are imbibed and adsorbed at additional sorption sites.
Department of Chemistry, Mississippi State University, MS 39762, USA. Electronic address: me200@msstate.edu.
Matthew
M
Essandoh
Department of Chemistry, Mississippi State University, MS 39762, USA.
Daniel
D
Wolgemuth
Department of Chemistry, Mississippi State University, MS 39762, USA.
Charles U
CU
Pittman
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Dinesh
D
Mohan
Department of Chemistry, Mississippi State University, MS 39762, USA.
Todd
T
Mlsna
D015084:2,4-Dichlorophenoxyacetic Acid / Q000302:isolation & purification*; D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000302:isolation & purification*; D000327:Adsorption; D002606:Charcoal / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry / Q000302:isolation & purification*; D008897:Panicum / Q000737:chemistry*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*
D006540:Herbicides; D012996:Solutions; D014874:Water Pollutants, Chemical; C540010:biochar; D002606:Charcoal; D015084:2,4-Dichlorophenoxyacetic Acid; D008456:2-Methyl-4-chlorophenoxyacetic Acid
2,4-D; Adsorption; Isotherms; Low cost adsorbent; MCPA; Phenoxy herbicides