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New oxyethylated methyl dodecanoates with average degrees of oxyethylation (n) ranging between 5 and 14 (denoted OMD-n) were considered as nonionic surfactants for the removal of phenol, 4-methylphenol, and 4-nitrophenol from aqueous streams by the cloud point extraction technique. The cloud point (denoted CP) strongly increases with the average degree of oxyethylation n but is independent of OMD-n concentration, except at low concentration (i.e., < 10 g.L-1). CP can be related to the surfactant hydrophilicity by the following equation: CP(degree C) = 20.27 x HLBG - 245.8 (above 10 g.L-1 and in the absence of electrolyte), where HLBG refers to the OMD-n hydrophile-lipophile balance in Griffin's scale. The presence of electrolyte such as NaCl strongly decreases the cloud point [delta CP/delta [NaCl] approximately -(9 +/- 1) degrees C-M-1]. Many parameters influence the extraction of phenols in OMD-n-rich phases, including the characteristics of phenols (hydrophobicity, hydrogen-bond acidity, hydrogen-bond basicity, etc.), the average degree of oxyethylation of OMD-n (i.e., n), the concentration of electrolyte, the settling temperature (Tset), and overheating (delta T = Tset - CP). The distribution coefficients typically range between 20 and 100. Finally, the kinetics of the separation process is limited by the slow coalescence of the fine droplets of surfactant-rich phase formed above CP.

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Ethoxylation of alcohols, alkylphenols, and alkylamines has been studied in the presence of a few catalytic systems. Distribution constants were computed. Broad‐range distributed ethoxylates are formed in the presence of NaOH, and the distribution constants increase up to the homologue containing six oxyethylene units. Narrow‐range distributed ethoxylates are formed in the presence of calcium‐based catalysts. It is reflected in the values of the distribution constants because an increase with the growing number of oxyethylene units in successive homologue is not observed.