Biochars were produced by slow pyrolysis of corn stover under a nitrogen atmosphere at 450Ã‚Â°, 550Ã‚Â°, and 750Ã‚Â°C. The chars were subjected to artificial aging, i.e., repeatedly freezing and thawing or incubating moist char at 60Ã‚Â° and 110Ã‚Â°C. A total of 12 materials was produced and characterized. The total polycyclic aromatic hydrocarbon (PAH) contents of 450Ã‚Â° and 550Ã‚Â° chars were 1.4 and 0.2 mg kg-1, respectively. Extraction and analysis of PAHs in the 750Ã‚Â° char was performed, however the quality control associated with this assay indicated that PAHs could not be quantitatively extracted from this material by standard methods. Sorption and mild extraction experiments were performed. Mild extraction with 2-
hydroxypropyl-ÃŽÂ²-cyclodextrin (HPCD), mimics bioaccessibility. Pyrene was used as a probe compound. The sorption data were well described by Freundlich isotherms. Pyrene sorption was strong for all chars, with the amount sorbed at 1ÃŽÂ¼g L-1 dissolved pyrene ranging from 10 to the 6th
to over 10 to the 7th ÃŽÂ¼ g kg-1. The pyrene content of the chars was too low to be detected in the HPCD extracts, so the chars were spiked with pyrene
and allowed to equilibrate before extraction. Only 10 to 15% of added pyrene was HPCD-extractable from the 450Ã‚Â° char and 1 to 5% from the 550Ã‚Â° and 750Ã‚Â° chars. Aging had small but measureable effects on both sorption and HPCD extraction of pyrene.
|Name||RR Series (Illinois Sustainable Technology Center)|
- Polycyclic aromatic hydrocarbons
- Soil pollution -- Biological treatment