Regular Article
The Adsorption of Multinuclear Phenolic Compounds on Activated Carbon

https://doi.org/10.1006/jcis.1996.0432Get rights and content

Abstract

Pure compounds, whose structures model that of phenol-formaldehyde resins, were synthesized and their adsorption from ethanol solvent on activated carbon examined. Two series of compounds were studied, (i) those with methylene linkages substituted in only theortho- positions relative to the phenolic hydroxyl group (theortho- series), and (ii) those in which allpara- positions together with sufficientortho- positions were used to synthesize the compounds (thepara- series). Successive coupling of phenolic units to bis-(2-hydroxyphenyl)-methane and bis-(4-hydroxyphenyl)-methane resulted in tetra-, hexa-, and octa-nuclear species, which are referred to as tetramer, hexamer, and octamer, respectively, with the appropriate prefix (ortho- orpara-). Experimental adsorption isotherms could be fitted to the Langmuir equation. From the maximum amounts adsorbed for each compound, it was shown thatortho-linked species were adsorbed to a greater extent than theirpara-linked analogues. This could be attributed to ethanol being a better solvent for thepara-linked compounds relative to theortho- series. The differences in behavior toward solvent could be attributed to the presence of strong intramolecular hydrogen bonding in theortho-linked compounds, an interaction minimal (or absent) in thepara-linked series. This conclusion is supported by results from molecular modeling and intrinsic viscosity measurements for the compounds of interest.

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