Phosphate Removal From Aqueous Solution By Switchgrass-Derived Biochar Produced By Fast Pyrolysis.

The removal of phosphate from aqueous solution by biochar derived from switchgrass was investigated. Switchgrass-derived biochar was produced through fast pyrolysis at 450℃ and 800℃ and their physicochemical properties were determined. Batch adsorption experiments were performed to investigate the effect of contact time, initial pH, and ionic strength on the removal of phosphate by biochar. The results showed that the adsorption process was time dependant. The phosphate adsorption decreases as pH and electrolyte concentration increase. The removal of phosphate increased by increasing the production temperature. The pseudo second-order model fitted the data better than other mathematical models used to describe the adsorption kinetics of phosphate onto biochar. The adsorption equilibrium fitted well to both the Langmuir and Freundlich models. The characteristics of post-adsorption biochar were measured using XRD and FTIR. Based on the experimental results phosphate seem to be efficiently removed from solution by adsorbing onto MgO particles on the biochar surface. The results suggest that switchgrass-derived biochar pyrolized at higher temperature is an effective alternative inexpensive adsorbent, which can be used to reclaim phosphate from water or reduce phosphate leaching from fertilized soils.