Particle size- and crystallinity-controlled phosphorus release from biochars

Authors: JIAN, XIUMEI - State University Of New York (SUNY); Uchimiya, Sophie; ORLOV, ALEXANDER - State University Of New York (SUNY)

Submitted to: Energy and Fuels
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2019
Publication Date: 5/13/2019
Citation: Jian, X., Uchimiya, M., Orlov, A. 2019. Particle size- and crystallinity-controlled phosphorus release from biochars. Energy and Fuels. 33(6):5343-5351. https://doi.org/10.1021/acs.energyfuels.9b00680.
DOI: https://doi.org/10.1021/acs.energyfuels.9b00680

Interpretive Summary: Large-scale biochar field trials have been conducted worldwide to test for “carbon negative strategy” in the event of carbon credit and if other subsidies become enacted in the future. Once amended to the soil, biochar engages in complex organo-mineral interactions,fragmentation, transport, and other aging mechanisms exhibiting interactions with treatments including the irrigation and fertilizer application. National Academy of Sciences’ agricultural research priority specifically calls for “omics” fingerprinting of target analytes as “advanced analytics for managing the food and agricultural system.” This study developed a new method to monitor and predict that changes in phosphorus form it solubility (phosphorus speciation). Developed method will facilitate the application of emerging organic phosphorus fertilizer, in the place of rapidly depleting phosphate rock-based chemical fertilizer.

Technical Abstract: Controlled-release sterile organic phosphorus fertilizers could be co-produced with bioenergy by the existing thermochemical conversion platforms to minimize runoff contamination within the nexus of food, water, and energy. This study combined (i) particle size- (<38 vs. <600 micrometer) and pyrolysis temperature-dependent (200-800 °C in 100 °C intervals) phosphorus dissolution kinetics (pH 8.5 NaHCO3 over 18 d) with (ii) spectroscopic elucidation of changes in P crystallinity of shrimp shell biochars. Two-dimensional infrared correlation spectroscopy revealed an increase in P-O functional group (1043 cm-1) as a function of pyrolysis temperature and total P content. Broad and symmetrical P-O peak in 700 °C biochar (but not 400°C biochar or unpyrolyzed feedstock) was attributable to semi-crystalline phases. Those thermodynamically stable inorganic P phases in 700 °C biochar released higher orthophosphate concentration when pulverized to smaller size fractions (<38 µm). Pyrolysis temperature dependence in total phosphate release (400 °C biochar >feedstock>700 °C biochar) indicated a complex interplay of solid-phase P speciation, dissolved organic carbon concentration, and size-dependent reactivity and colloidal fraction of phosphorus phases in biochars.