A membrane process to recover extractant D2EHPA in aqueous phase

A membrane adsorption–extraction process to recover di-(2-ethylhexyl) phosphate (D2EHPA) from the raffinate is developed, i.e. a hollow fiber membrane extraction module, in which raffinate flows in the tube side and n-heptane used as the “extractant” flows in the shell side. The emulsion with D2EHPA, n-heptane and Triton X-114 was used as the simulated raffinate, and it was proved that both the affinity of membrane for oil droplets and the extraction of D2EHPA by n-heptane contribute to the method. Via recycling the feed, the final recovery efficiency of D2EHPA could be as high as 90%. The effects of two main operating conditions, tube side velocity and shell side velocity, were investigated. The tube side velocity was found to be an essential operation factor, while the shell side velocity had a slight influence.