Partition coefficients for phenol; o-, m-, and p-cresols; 3,5-xylenol; and R-naphthol in an ionic liquid/water twophase system were measured at 298.2 K. 1-Butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6 ]) was used as the ionic liquid. Further, the infinite dilution partition coefficients were also determined by extrapolation. The infinite dilution partition coefficients were correlated by regular solution theory. Interaction parameters between phenolic compounds and [bmim][PF 6 ] pairs were determined by plotting the infinite dilution partition coefficients against the solubility parameters of the phenolic compounds. The correlated results are in good agreement with the experimental data.

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Acidic biotrickling filters (BTFs) can be used for simultaneous removal of hydrogen sulfide (H2S) and siloxane from biogas. In this study, the performance of a BTF under different acidic pH conditions was investigated. The removal profile of H2S showed that 90% of H2S removal was achieved during the first 0.4 m of BTF height with down-flow biogas. Decamethylcyclopentasiloxane (D5) removal decreased from 34.5% to 15.6% when the pH increased from 0.88 to 3.98. Furthermore, the high partition coefficient (P) of D5 obtained in under higher pH condition was attributed to the higher total ionic strength resulting from the addition of NaOH solution and mineral medium. The linear increase in D5 removal with the mass transfer coefficient (kL) indicated that the acidic recycling liquid accelerated the mass transfer of D5 in the BTF. Therefore, the lower P value and higher kL under acidic pH conditions lead to the efficient removal of D5. However, the highly acidic pH 0.9 blocked mass transfer of H2S and O2 gases to recycling liquid. Low sulfur oxidation activity and low Acidithiobacillus sp. content also deteriorated the biodegradation of H2S. Operating the BTF at pH 1.2 was optimal for simultaneously removing H2S and siloxane.

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