Sugarcane straw biochar: effects of pyrolysis temperature on barite dissolution and Ba availability under flooded conditions

• Published in: Biochar (Online) 2024-10, Vol.6 (1), p.1-13, Article 83
• Main Authors: Viana, Douglas G., Soares, Matheus B., Alleoni, Luís Reynaldo F., Egreja Filho, Fernando B., Duckworth, Owen W., Regitano, Jussara Borges
• Format: Article
• Language: English
• Subjects: Agriculture; Anoxic soil; Ba remediation; Biochar for remediation of emerging inorganic pollutants in the environment; Ceramics; Composites; DRIFT; Earth and Environmental Science; Environment; Environmental Engineering/Biotechnology; Fossil Fuels (incl. Carbon Capture); Glass; Natural Materials; Original Research; Redox potential; Renewable and Green Energy; Soil Science & Conservation; Wetlands
• ISSN: 2524-7867; 2524-7867
• DOI: 10.1007/s42773-024-00371-w

Reductive dissolution of barium (Ba) sulfate in wetland soils may increase Ba bioavailability in the environment, yet no information is available regarding Ba remediation using biochar. This study investigated the effectiveness of sugarcane ( Saccharum officinarum ) straw biochar pyrolyzed at 350 °C (BC350), 550 °C (BC550), and 750 °C (BC750) in inhibiting barite dissolution and, consequently, Ba availability in a soil artificially spiked with barite and flooded for 365 days. Increasing pyrolysis temperature alters the carbon structure, and increases dehydration and depolymerization, resulting in more stable biochar that releases less DOC (8.6-fold decrease from BC350 to BC750). Additionally, high-temperature biochar (BC750) had 1.7 times higher carbon (C) content, 2.4 times higher ash content, and a 13.1 times greater specific surface area (SSA) than low-temperature biochar (BC350). Amending soil with BC750 increased pH but did not promote reducing conditions, and thus did not promote barite dissolution. Conversely, greater DOC in low-temperature biochar, particularly BC350, favored reducing conditions and increased barite dissolution by 23%, with BC550 also showing an 18% increase. This enhancement led to a greater pool of Ba sorbed into more labile exchangeable sites. In summary, pyrolysis temperature affects biochar attributes, which in turn influences the soil geochemical environment and Ba speciation. Low-temperature biochar (BC350) shows potential as an amendment to increase the bioavailable Ba pool in assisted remediation programs, such as biochar-assisted phytoremediation. Graphical Abstract Highlights • Biochar pyrolysis temperature affected both redox potential and barite dissolution. • BC750 mitigated barite dissolution while modifying exchangeable sorption sites. • DOC release from low temperature biochar promoted barite reductive dissolution. • BC350 may enhance biochar-mediated phytoremediation applications.