ABSTRACTI evaluated the effect of introducing other functional groups to phenol on adsorption by soil and developed equilibrium adsorption isotherms for phenol, catechol, resorcinol, and the ortho, meta, and para isomers of cresol, methoxyphenol, nitrophenol, and chlorophenol. Introducing —CH3, —OCH3, —NO2, or —Cl groups to phenol resulted in increased adsorption. With the exception of o-nitrophenol, adsorption of the phenols studied occurred by H-bonding to sites on soil surfaces. Adsorption was generally higher than would be predicted for hydrophobic sorption, presumably due to H-bonding. Ortho-nitrophenol was apparently adsorbed hydrophobically, and H-bond formation was not indicated. Adsorption of the meta- and para- substituted phenols was related to substituent effects on the basicity of the phenolic hydroxyl. Adsorption was enhanced by electron-donating substituents, indicating that the phenolic —OH group formed H-bonds by acting as a proton acceptor. Ortho substitution of —CH3, —OCH3, and —Cl resulted in decreased adsorption compared with para- substitution, due to steric hindrance of H-bonding. In the case of catechol, the formation of multiple H-bonds by adjacent functional groups enhanced adsorption. I also measured the di- and trichlorinated phenols. Increasing the degree of chlorination of phenol resulted in increased adsorption. Competitive effects of adsorption from solutions containing two or three phenolic compounds were evaluated. Adsorption was adversely affected by the presence of these other solutes. The competitive effect became more pronounced with an increasing number of compounds in solution.
I evaluated the effect of introducing other functional groups to phenol on adsorption by soil and developed equilibrium adsorption isotherms for phenol, catechol, resorcinol, and the ortho, meta, and para isomers of cresol, methoxyphenol, nitrophenol, and chlorophenol. Introducing —CH3, —OCH3, —NO2, or —Cl groups to phenol resulted in increased adsorption. With the exception of o-nitrophenol, adsorption of the phenols studied occurred by H-bonding to sites on soil surfaces. Adsorption was generally higher than would be predicted for hydrophobic sorption, presumably due to H-bonding. Ortho-nitrophenol was apparently adsorbed hydrophobically, and H-bond formation was not indicated. Adsorption of the meta- and para- substituted phenols was related to substituent effects on the basicity of the phenolic hydroxyl. Adsorption was enhanced by electron-donating substituents, indicating that the phenolic —OH group formed H-bonds by acting as a proton acceptor. Ortho substitution of —CH3, —OCH3, and —Cl resulted in decreased adsorption compared with para- substitution, due to steric hindrance of H-bonding. In the case of catechol, the formation of multiple H-bonds by adjacent functional groups enhanced adsorption. I also measured the di- and trichlorinated phenols. Increasing the degree of chlorination of phenol resulted in increased adsorption. Competitive effects of adsorption from solutions containing two or three phenolic compounds were evaluated. Adsorption was adversely affected by the presence of these other solutes. The competitive effect became more pronounced with an increasing number of compounds in solution.
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