Evidence for a pore-filling mechanism in the adsorption of aromatic hydrocarbons to a natural wood char
Dianne L. Poster, Thanh H. Nguyen, Roberta A. Brown, William P. Ball
Sorption isotherms for five aromatic hydrocarbons were obtained with a natural wood char (NC1) and its residue after solvent extraction (ENC1). Substantial isotherm nonlinearity was observed in all cases. ENC1 showed higher BET surface area, higher nitrogen-accessible micropore volume, and lower mass of extractable organic chemicals, including quantifiable polycyclic aromatic hydrocarbons (PAHs), while the two chars showed identical surface oxygen/carbon (O/C) ratio. For two chlorinated benzenes that normally condense as liquids at the temperatures used, sorption isotherms with NC1 and ENC1 were found to be statistically identical. For the solid-phase compounds (1,4- dichlorobenzene (1,4-DCB) and two PAHs), sorption was statistically higher with ENC1, thus demonstrating sorption effects due to both (1) authigenic organic content in the sorbent and (2) the sorbate's condensed state. Polanyi-based isotherm modeling, pore size measurements, and comparisons with activated carbon show the relative importance of adsorptive pore filling and help explain results. With both chars, maximum sorption increased in the order of decreasing molecular diameter: phenanthrene
, Nguyen, T.
, Brown, R.
and Ball, W.
Evidence for a pore-filling mechanism in the adsorption of aromatic hydrocarbons to a natural wood char, Environmental Science and Technology, [online], https://doi.org/10.1021/es0617845
(Accessed November 29, 2023)