Sorption of polycyclic aromatic hydrocarbons (PAHs) to biochar and potential PAH bioavailability

Presented by Holm actually June 2013

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Char was produced from corn stover by slow pyrolysis under nitrogen at 450°, 550°, and 750°C. Sub-samples of char were subjected to artificial aging for 30 days. The total PAH concentrations in all fresh and aged chars were below 1.5 mg/kg. Sorption and bioavailability of pyrene, a polycyclic aromatic hydrocarbon, were characterized for fresh and aged chars. Pyrene sorbed strongly to all chars. The minimum distribution coefficient for 1 µg/L (1 nM) dissolved pyrene was 106. Freundlich isotherms fit the sorption data very well. The effect of corn stover char on pyrene bioavailability was characterized by extraction with 2-hydroxypropyl-β-cyclodextrin (HPCD). For all chars tested, less that 10% of added pyrene was extractable with HPCD. In some cases, less than 1% was extractable. This result is consistent with the strong sorption of pyrene to corn stover char.