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Investigating biochar as a tool for environmental remediation
Citation:
Johnson, M., J. Maynard, AND P. Nico. Investigating biochar as a tool for environmental remediation. Presented at 2012 Annual Meeting of the Soil Science Society of America, Cincinnati, OH, October 21 - 24, 2012.
Impact/Purpose:
Biochar is a carbon-rich material that is produced from the heating of biomass in the absence of oxygen; a process known as pyrolysis. Pyrolysis is one of several processes that can be used to extract energy from biomass. In addition to biochar, combustible gases and oils are also produced. Biochar is a solid and is being proposed as a cost-effective, carbon negative soil amendment for environmental remediation. Research has demonstrated the efficacy of biochar to sorb heavy metals and agricultural chemicals from contaminated soils, thus effectively reducing the potential for metal and chemical contamination of surface and ground waters. This research investigates the sorption of heavy metals by biochar to evaluate the potential for designing biochars to target sorption of specific heavy metals to effectively complex the metals and remediate contaminated soils. Advanced analytical techniques were used to evaluate the nature and efficacy of metal complexation. Our results indicate that higher temperature biochars have an increased capacity for metal sorption over those produced at lower temperatures. We are using these results to develop a decision support framework for producing biochar that has properties to match the specific remediation needs of contaminated soils, thereby improving the likelihood of effective remediation.
Description:
Biochar is being proposed as a cost-effective, carbon negative soil amendment for environmental remediation. Research has demonstrated the efficacy of biochar to sorb heavy metals and agricultural chemicals from contaminated soils, thus effectively reducing the potential for metal and chemical contamination of surface and ground waters. In this study we investigate the ability of biochar produced from a single feedstock (Doulas fir wood chips) across a range of charring temperatures (300 – 700 °C) to bind with metals. We characterized the biochars using a variety of techniques including total elemental and isotope analysis, pH, FTIR spectroscopy, surface area and pore size analysis, proximal analysis and metal sorption studies. Biochars with sorbed metals were further characterized using synchrotron-based XAS, XANES and EXAFS. Our results indicate that higher temperature biochars have an increased capacity for metal sorption over those produced at lower temperatures. We report on the biochar properties and metal sorption characteristics, and provide a decision support framework for producing biochar that has properties to match the specific remediation needs of contaminated soils, thereby improving the likelihood of effective remediation.