Recovery of carboxylic acids C₁C₃ with organophosphine oxide solvating extractants

Abstract

This study was aimed at examining the use of the organophosphine oxides Cyanex  921 and Cyanex  923 for the extraction of formic, acetic and propionic acids from aqueous solutions. The stripping of monocarboxylic acids with water from the loaded extractants was also examined. The studies were aimed at determining the equilibrium conditions for extraction and stripping. Overall, the effect of the kind of extractant was not significant although Cyanex  921 extracted carboxylic acids slightly better than Cyanex  923 with 1:1 complexes being formed by both extractants with the acids during extraction. The efficiency of extraction depended on temperature, acid concentration and solvent, with toluene a better diluent for the extractants than octane or Exxsol  D 220/230. Extraction efficiency increased as the concentration of acid in the feed decreased and, also, as the temperature increased, the amount of acid extracted decreased. The extraction and stripping isotherms were determined. The apparent enthalpy and entropy of the extraction reaction were determined. Distribution data for the transfer of carboxylic acids from aqueous (NaCl) solutions to organic solvents in the presence of trialkylphosphine oxide were determined at 293 K with the distribution ratios increasing as the concentration of NaCl increased.

A study on a combined process for the treatment of phenolic resin plant effluents

“…Since the oxidation was performed in alkaline medium, the pH of the resultant solution was as high as 12. Therefore, the resultant formate solution was first acidified with concentrated sulphuric acid to decrease pH below pK a of formic acid (pK a = 3.56 [15]) and for that a reasonable amount of acid was used. To adjust the pH around 2.0 of the formate solution, 40 mL/L of concentrated sulphuric acid was required.…”

“…Further the recovery of formic acid was carried out by solvent extraction with Cyanex 923 and Alamine 336. In literature, some other works are also published related to formic acid extraction using phosphate containing extractants [15,16] and tertiary amines [17][18][19]. It is worth mentioning that formic acid is used in many industries such as textiles, natural rubber and leather processing.…”

Mathematical modeling of cadmium(II) solvent extraction from neutral and acidic chloride media using Cyanex 923 extractant as a metal carrier

“…The removal of cadmium(II) from aqueous chloride solutions using Cyanex 923 as an extractant was described as promising, mainly due to the high extraction efficiency [4][5][6][7][8]. This paper deals with the development of a mathematical model of cadmium(II) solvent extraction that leads to the determination of the process equilibrium parameters.…”

Optimization and Evaluation of Organic Acid Recovery from Kraft Black Liquor Using Liquid-Liquid Extraction

“…Senol [16] deduced a molar loading of greater than one for carboxylic acids removal from water by alamine 336 in halogenated hydrocarbon diluents. The use of tri-n-ctylphosphine oxide (TOPO) as an extractant for the removal of fatty acids from aqueous solutions has been discussed in several papers [15,[18][19][20][21][22][23][24][25]. Because of its high hydrogen-bonding acceptor basicity, TOPO complexes strongly with a carboxylic acid in an organic phase, enhancing the transfer of the carboxylic acid to the extract phase.…”