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Title: Pseudo-hydroxide extraction in the separation of sodium hydroxide from aqueous solutions using alkyl phenols

Abstract

Pseudo-hydroxide extraction of sodium hydroxide from aqueous solution using four alkyl phenols of nearly identical molecular weight in 1-octanol at 25 degrees C was examined to understand the effect of alkyl substituents. The order of extraction strength among the four alkyl phenols tested was 4-tert-octylphenol. 3,5-di-tertbutylphenol. 2,4-di-tert-butylphenol. 2,6-di-tert-butyl-4-methylphenol. A good correlation with phenol pK(a) was observed, indicating that extraction strength is determined by phenol acidity, as modified by steric effects in proximity to the phenol - OH group. The effective partition ratios (P-eff) of two phenols from 1 M NaOH solution were determined, showing that the phenols remain predominantly in the 1-octanol phase even when converted to their sodium salts. However, the hydrophobicity of the tested phenols may not be sufficient for process purposes. The equilibrium constants for the governing extraction equilibria were determined by modeling the data using the program SXLSQI, supporting the cation-exchange extraction mechanism. The proposed mechanism consists of two simple sets of equilibria for a. Ion-pair extraction to give Na+OH- ion pairs and corresponding free ions in 1-octanol the phase and b. Cation exchange by monomeric phenol molecules (HAs) to form monomeric organic-phase Na(+)A(-) ion pairs and corresponding free organic-phase ions.

Authors:
 [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1098194
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Solvent Extraction and Ion Exchange; Journal Volume: 24; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
Pseudo-hydroxide extraction; alkyl phenols; alkyl substituents; SXLSQI; equilibria; sodium hydroxide; equilibrium modeling

Citation Formats

Kang, Hyun Ah, and Moyer, Bruce A. Pseudo-hydroxide extraction in the separation of sodium hydroxide from aqueous solutions using alkyl phenols. United States: N. p., 2006. Web. doi:10.1080/07366290600646822.
Kang, Hyun Ah, & Moyer, Bruce A. Pseudo-hydroxide extraction in the separation of sodium hydroxide from aqueous solutions using alkyl phenols. United States. doi:10.1080/07366290600646822.
Kang, Hyun Ah, and Moyer, Bruce A. Sun . "Pseudo-hydroxide extraction in the separation of sodium hydroxide from aqueous solutions using alkyl phenols". United States. doi:10.1080/07366290600646822.
@article{osti_1098194,
title = {Pseudo-hydroxide extraction in the separation of sodium hydroxide from aqueous solutions using alkyl phenols},
author = {Kang, Hyun Ah and Moyer, Bruce A},
abstractNote = {Pseudo-hydroxide extraction of sodium hydroxide from aqueous solution using four alkyl phenols of nearly identical molecular weight in 1-octanol at 25 degrees C was examined to understand the effect of alkyl substituents. The order of extraction strength among the four alkyl phenols tested was 4-tert-octylphenol. 3,5-di-tertbutylphenol. 2,4-di-tert-butylphenol. 2,6-di-tert-butyl-4-methylphenol. A good correlation with phenol pK(a) was observed, indicating that extraction strength is determined by phenol acidity, as modified by steric effects in proximity to the phenol - OH group. The effective partition ratios (P-eff) of two phenols from 1 M NaOH solution were determined, showing that the phenols remain predominantly in the 1-octanol phase even when converted to their sodium salts. However, the hydrophobicity of the tested phenols may not be sufficient for process purposes. The equilibrium constants for the governing extraction equilibria were determined by modeling the data using the program SXLSQI, supporting the cation-exchange extraction mechanism. The proposed mechanism consists of two simple sets of equilibria for a. Ion-pair extraction to give Na+OH- ion pairs and corresponding free ions in 1-octanol the phase and b. Cation exchange by monomeric phenol molecules (HAs) to form monomeric organic-phase Na(+)A(-) ion pairs and corresponding free organic-phase ions.},
doi = {10.1080/07366290600646822},
journal = {Solvent Extraction and Ion Exchange},
number = 3,
volume = 24,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}