Biochar was produced from the fast pyrolysis of Douglas fir (DFBC). Magnetic biochar (MDFBC) was prepared by magnetite (Fe3O4) precipitation onto the biochar’s surface from an aqueous Fe3+/Fe2+ solution upon NaOH treatment. The resulting MDFBC was used to remove phosphate from water. The surface chemistry and composition of the MDFBC were examined by SEM, SEM-EDX, TEM, PZC, XPS, XRD, elemental analysis, and surface area measurements. Batch sorption studies were carried out from pH 2 to 10 and adsorbate concentrations from 5 to 1000 ppm at 25, 35 and 45°C. MDFBC suspensions in the contaminated solutions were vortexed for two min and then magnetically removed. Remediated solutions were then analyzed using UV-Visible spectroscopy. The amount of phosphate adsorbed onto MDFBC was higher at low pH values and decreased with increasing pH. MDFBC sorption at 25, 35 and 45°C was evaluated using the Langmuir, Freundlich, Sips, Redlich–Peterson, and Toth adsorption isotherm models. Results indicate that MDFBC removes the phosphates and remediated the solutions more effectively than the DFBC. The fast adsorption kinetics and high adsorption capacities of MDFBC could be advantageously employed in filtration devices, columns, or as shown here, in batch operations with stirring to speed adsorption, followed by magnetic separation of the adsorbent for regeneration.

Rapid removal of phosphate from wastewater using magnetized fast pyrolysis biochar from waste Douglas fir

253rd National Meeting (2017)

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