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ARS Home » Southeast Area » Auburn, Alabama » Soil Dynamics Research » Research » Publications at this Location » Publication #418121

Research Project: Sustaining Productivity and Ecosystem Services of Agricultural and Horticultural Systems in the Southeastern United States

Location: Soil Dynamics Research

Title: Influence of iron-modified biochar on phosphate transport and deposition in saturated porous media under varying pH, ionic strength, phosphate concentrations, and biochar dosage

Author
item KUMAR, RAKESH - Auburn University
item LAMBA, JASMEET - Auburn University
item ADHIKARI, SUSHIL - Auburn University
item KASERA, NITESH - Auburn University
item Torbert Iii, Henry

Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2024
Publication Date: 12/22/2024
Citation: Kumar, R., Lamba, J., Adhikari, S., Kasera, N., Torbert III, H.A. 2024. Influence of iron-modified biochar on phosphate transport and deposition in saturated porous media under varying pH, ionic strength, phosphate concentrations, and biochar dosage. Chemosphere. 370:143932. https://doi.org/10.1016/j.chemosphere.2024.143932.
DOI: https://doi.org/10.1016/j.chemosphere.2024.143932

Interpretive Summary: Phosphorus is one of the essential nutrients required for plants; however, loss of phosphorus from agricultural areas results in water quality impairment. This research aims to investigate the transport and deposition of phosphate at different solution chemistry and phosphate-biochar dosages under (a) individual phosphate flow, (b) biochar transport followed by phosphate, and (c) co-transport of biochar-phosphate in saturated porous media. Breakthrough curves (BTCs) for phosphate were developed to understand the effect of pine wood raw biochar (BC) and iron-modified biochar (Fe-BC) on phosphate transport and deposition under varying solutions, pH (5.5-10.5), ionic strength (0-10 mM), phosphate (10-20 mg/L), and biochar dosages (100-200 mg/L) in saturated porous media. Phosphate retardation using biochar was observed due to electrostatic attraction at liquid-solid interfaces. Results indicated overall that modeling of transport and deposition of phosphate and biochar are significant to understanding fate, biochar-phosphate interactions, and remediation designs in saturated porous media.

Technical Abstract: Phosphorus is one of the essential nutrients required for plants; however, loss of phosphorus from agricultural areas results in water quality impairment. This research aims to investigate the transport and deposition of phosphate at different solution chemistry and phosphate-biochar dosages under (a) individual phosphate flow, (b) biochar transport followed by phosphate, and (c) co-transport of biochar-phosphate in saturated porous media. Breakthrough curves (BTCs) for phosphate were to understand the effect of pine wood raw biochar (BC) and iron-modified biochar (Fe-BC) on phosphate transport and deposition under varying solutions, pH (5.5-10.5), ionic strength (0-10 mM), phosphate (10-20 mg/L), and biochar dosages (100-200 mg/L) in saturated porous media. Results revealed that maximum deposition of BC and Fe-BC at high ionic strength (IS), i.e., 10 mM compared to 0 mM. Besides, BTCs of phosphate (10-20 mg/L) transport at increased IS showed delayed elute and long tailing curves compared to BTCs of tracer. Further, phosphate transport using BTCs in biochar-mediated saturated porous media was investigated at 10-20 mg/L phosphate, where maximum retardation (37%) was observed at pH 6.7±0.1 and 0 mM IS due to the availability of active sites for 10 mg/L phosphate using Fe-BC compared to BC. The BTCs of phosphate transport analyzed at pH 6.7±0.1 and 0-10 mM IS showed phosphate deposition of 37% and 40% in Fe-BC-mediated columns for 0 mM and 10 mM, respectively, compared to BC-mediated columns. For BC, maximum phosphate adsorption was observed at pH 5.5±0.1, whereas at pH 6.7±0.1 for Fe-BC for 10 mM IS, and thus, least adsorption was observed at pH of 10.5±0.1 for both BC and Fe-BC. Similar phosphate retardation BTCs for BC and Fe-BC at 10 mM were observed with adsorption of 40% phosphate for 100-200 mg/L biochar dose. Besides, co-transport and deposition of biochar and phosphate, considering with and without ripening effect, were analyzed at pH 6.7±0.1 and 10 mM for a biochar dose of 100 mg/L and phosphate of 10 mg/L. Phosphate retardation using biochar was observed due to electrostatic attraction at liquid-solid interfaces. Overall, modeling of transport and deposition of phosphate and biochar are significant to understanding fate, biochar-phosphate interactions, and remediation designs in saturated porous media.