Study of bulk liquid membrane as a separation technique to recover acetic and propionic acids from dilute solutions

133-138Liquid membranes incorporating potential chemical species can perform rapid and selective transport of a variety of guest species and that too being much energy efficient than other separation methods. Separation characteristics of a bulk liquid membrane were investigated to recover acetic acid and propionic acid from dilute aqueous solutions by reactive extraction process. The liquid membrane made up of trioctylamine as an extractant and toluene as an organic diluent was tested. The membrane was kept in contact with two aqueous phases namely acidic feed phase and alkaline strip phase. The parameters affecting the extraction of the acid including nature of the feed phase, sodium hydroxide concentration in the strip phase and concentration of trioctylamine in membrane phase were investigated. The membrane system was observed to have potential to extract both the acids which was confirmed with the increase in the percentage extraction and the mass-transfer coefficient with time. The set-up under investigation could extract about 40% of the acid in first five hours of operation under defined conditions. The set-up was found to be more favourable for propionic acid in comparison to acetic acid as the difference in extraction efficiency widens with the increase in the strength of the strip phase solution