Phenoxy herbicide removal from aqueous solutions using fast pyrolysis switchgrass biochar

作者：Essandoh Matthew^*; Wolgemuth Daniel; Pittman Charles U Jr; Mohan Dinesh; Mlsna Todd

来源：Chemosphere, 2017, 174: 49-57.

DOI：10.1016/j.chemosphere.2017.01.105

• 2,4-D
• MCPA
• Low cost adsorbent
• Adsorption
• Isotherms
• Phenoxy herbicides

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, pH(pzc), 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 degrees C. Adsorption isotherms were evaluated from 25 to 45 degrees C using both two parameter (Freundlich and Langmuir) and three parameter (Redlich-Peterson and Toth) adsorption isotherm models. The maximum adsorption capacities for 2,4dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) were Q(sGB)(0) similar or equal to 134 mg/g and Q(SGB)(0)similar or equal to 50 mg/g, respectively, at pH 2. This low surface area switchgrass biochar (1.1 m(2)/g) can adsorb far more MCPA per unit of measured surface area (45 mg/m(2)) than high surface area commercial activated carbons (1050-1150 m(2)/g) which absorb only 0.08-0.11 mg/m(2), 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.

• 出版日期2017-5