The role of dissolved pyrogenic carbon from biochar in the sorption of As (V) in biogenic iron (oxyhydr)oxides

Author(s)

Soares, Matheus B. ; Duckworth, Owen W. ; Alleoni, Luis R. F.

• Document type: Journal article
• Source: Science of The Total Environment; v. 865, p. 10-pg., 2023-03-20.

Abstract

Water contamination by arsenic (As) affects millions of people around the world, making techniques to immobilize or remove this contaminant a pressing societal need. Biochar and iron (oxyhydr)oxides [in particular, biogenic iron (oxyhydr)oxides (BIOS)] offer the possibility of stabilizing As in remediation systems. However, little is known about the potential antagonism in As sorption generated by the dissolved organic carbon (DOC) from biochar, or whether DOC affects how As(V) interacts with BIOS. For this reason, our objectives were to evaluate the i) As (V) sorption potential in BIOS when there is presence of DOC from pyrolyzed biochars at different temperatures; and ii) identify whether the presence of DOC alters the surface complexes formed by As(V) sorbed in the BIOS. We conducted As(V) sorption experiments with BIOS at circumneutral pH conditions and in the presence of DOC from sugarcane (Saccharum officinarum) straw biochar at pyrolyzed 350 (BC350) and 750 degrees C (BC750). The As(V) content was quantified by inductively coupled plasma mass spectrometry, and the BIOS structure and As(V) sorption mechanisms were investigated by X-ray absorption spectroscopy. In addition, the organic moieties comprising the DOC from bio-chars were investigated by attenuated total reflectance Fourier transform infrared spectroscopy. The addition of DOC did not change the biomineral structure or As(V) oxidation state. The presence of DOC, however, reduced by 25% the sorption of As(V), with BC350 being responsible for the greatest reduction in As(V) sorption capacity. Structural modeling revealed As(V) predominantly formed binuclear bidentate surface complexes on BIOS. The presence of DOC did not change the binding mechanism of As(V) in BIOS, suggesting that the reduction of As(V) sorption to BIOS was due to site blocking. Our results bring insights into the fate of As(V) in surface waters and provide a basis for understanding the competitive sorption of As(V) in environments with biochar application. (AU)

• FAPESP's process: 20/13700-4 - Effect of pyrogenic carbon in arsenic species and their interaction with biogenic iron oxide in a contaminated sediment amended with biochar
• Grantee: Matheus Bortolanza Soares
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 19/06897-9 - Biogeochemistry of arsenic and lead in soil remediated with biochar
• Grantee: Matheus Bortolanza Soares
• Support Opportunities: Scholarships in Brazil - Doctorate