Rapid removal of nitrate and fluoride ions from aqueous solutions were successfully studied using α-FeOOH and γ-Fe2O3 modified biochar. Magnetic (α-FeOOH and γ-Fe2O3) modification was obtained by pyrolyzing FeCl3 impregnated Douglas Fir biochar at 600 °C for 1h under N2. Magnetized and non-magnetized biochars were characterized using scanning electron microscopy (SEM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), surface area measurement (S BET), point of zero charge (PZC) measurements, X-ray diffractometry (XRD) analysis, hysteresis and magnetic moment measurements, and X-ray photoelectron spectroscopy (XPS). Biochar surfaces were successfully magnetized by both α-FeOOH and γ- Fe2O3 particles formation. Batch sorption studies of nitrate and fluoride were performed at pH values from 2 to 11, and temperatures of 298, 308 and 318 K. The magnetized biochar removed more nitrate and fluoride than the non-magnetized biochar, suggesting that the iron oxide particles formed generate additional nitrate and fluoride adsorption sites. Both nitrate and fluoride adsorption on α-FeOOH and γ- Fe2O3-modified biochar remained unchanged with a rise of solution pH from 2-10. Sorption was evaluated from 298 to 318 K using the Langmuir and Freundlich isotherm models and Langmuir adsorption capacities as high as 15.5 mgg-1 for nitrate and 9.04 mgg-1 for fluoride were observed. The mechanisms of nitrate and fluoride ions adsorption on chitosan-modified biochar were studied by XPS. The electrostatic attractions and H-bonding with iron oxide particles are believed to play a major role in nitrate and fluoride adsorption with the studied pH range.

Removal of nitrate and fluoride anions from aqueous solution using α-FeOOH and γ-Fe2O3 modified biochar with fast adsorption kinetics

255th National Meeting (2018)

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