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Synthesis of magnetic wheat straw for arsenic adsorption

Tian, Ye, Wu, Min, Lin, Xiaobo, Huang, Pei, Huang, Yong
Journal of hazardous materials 2011 v.193 pp. 10-16
X-ray diffraction, adsorption, agricultural wastes, aqueous solutions, arsenic, coprecipitation, iron oxides, magnetic fields, models, pH, sodium hydroxide, sorption isotherms, wheat straw
Magnetic wheat straw (MWS) with different Fe₃O₄ content was synthesized by using in-situ co-precipitation method. It was characterized by powder X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). This material can be used for arsenic adsorption from water, and can be easily separated by applied magnetic field. The introduction of wheat straw template highly enhanced the arsenic adsorption of Fe₃O₄. Among three adsorption isotherm models examined, the data fitted Langmuir model better. Fe₃O₄ content and initial pH value influenced its adsorption behavior. Higher Fe₃O₄ content corresponded to a higher adsorption capacity. In the pH range of 3–11, As(V) adsorption was decreased with increasing of pH; As(III) adsorption had the highest capacity at pH 7–9. Moreover, by using 0.1molL⁻¹ NaOH aqueous solution, it could be regenerated. This work provided an efficient way for making use of agricultural waste.