Sorption of Phenol and Alkylphenols from Aqueous Solution onto Organically Modified Montmorillonite and Applications of Dual-Mode Sorption Model

Abstract

Single- and multisolute competitive sorptions were carried out in a batch reactor to investigate the uptake of phenol, 4-methylphenol (MeP), 2,4-dimethylphenol (DMeP), and 4-ethylphenol (EtP) dissolved in water at 25°C onto organically modified montmorillonite. Hexadecyltrimethylammonium (HDTMA) cation was exchanged for metal cations on the montmorillonite to the extent of the cation-exchange capacity (CEC) of the montmorillonite to prepare HDTMA–montmorillonite, changing its surface property from hydrophilic to organophilic. It was observed from the experimental results that the adsorption affinity on HDTMA–montmorillonite was in the order 4-EtP ≈ 2,4-DMeP 4-MeP phenol. The Langmuir, dual-mode sorption (DS), and Redlich–Peterson (RP) models were used to analyze the single-solute sorption equilibria. The competitive Langmuir model (CLM), competitive dual-mode sorption model (CDSM), and ideal adsorbed solution theory (IAST), coupled with the single-solute models (i.e., Langmuir, DS, and RP models), were used to predict the multisolute competitive sorption equilibria. All the models considered in this work yielded favorable representations of both single- and multisolute sorption behaviors. DSM, CDSM, and IAST coupled with the DSM were found to be other satisfactory models to describe the single- and multisolute sorption of the phenolic compounds onto HDTMA–montmorillonite.