Campus Units

Mechanical Engineering, Agricultural and Biosystems Engineering, Chemical and Biological Engineering, Bioeconomy Institute (BEI)

Document Type


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Submitted Manuscript

Publication Date


Journal or Book Title

ACS Sustainable Chemistry & Engineering




Biochars have been suggested to have P capture potential from effluent streams and to recycle the captured P to agricultural soils. However, most biochars have low P sorption capacity. The objective of this study was to engineer biochar for enhanced P sorption affinity. Biochar was produced from corn stover biomass pre-treated with FeSO4 (ISIB) using autothermal (air-blown) pyrolysis at 500 °C. Point of zero charge (pHZPC) shifted from 8.48 to 4.31, indicating that Fe treatment increased the dominance of acid functional groups. Batch equilibration isotherm study showed that ISIB had 11–12 times more P sorption capacity (3763 versus 46,300 mg kg–1 and 6704 versus 48,821 mg kg–1 for non-oxidized and oxidized conditions, respectively), while P desorption rate was ∼1/3 relative to the control biochar. A column leaching study also shows that ISIB was effective for removing P from simulated agricultural effluent. XRD (X-ray diffraction) and SEM-EDS (scanning electron microscopy–energy-dispersive X-ray spectrometry) analyses showed the P sorption was predominately through inner-sphere surface complexation followed by surface precipitation and that P is preferentially sorbed by hematite (α-Fe2O3) relative to magnetite (FeIII2O3 + FeIIO) or maghemite (γ-Fe2O3). This study demonstrates that ISIB can be produced by pyrolyzing corn stover with FeSO4, and the resulting ISIB is effective for adsorption and recycling of P. When loaded with P, the ISIB can potentially be used as a slow-release P fertilizer.


This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in ACS Sustainable Chemistry & Engineering, copyright © American Chemical Society after peer review. To access the final edited and published work see DOI: 10.1021/acssuschemeng.0c06108. Posted with permission.

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American Chemical Society



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