Heavy metal removal by non-Newtonian emulsion liquid membrane dispersed in Taylor-Couette flow: experiments and modeling

摘要

The extraction of selected heavy metals from aqueous solutions was investigated using emulsion liquid membranes (ELMs). These ELMs were stabilized by converting the liquid (oil) membrane phase into non-Newtonian fluid through the addition of appropriate amounts of high-molecular-weight polymers. The resulting ELMs were further dispersed in Taylor-Couette flow to minimize emulsion breakage. In this ELM process, Cyanex 301, 302, and 923 and DEHPA were used as carrier agents to facilitate the transport of metals across the liquid (oil) membrane. A mathematical model to predict metal extraction was developed by taking into account the pH change in the external phase, the effect of agitation speed on the size of emulsion globules, and the leakage rate, based on a classical shrinking core model. The proposed mathematical model was found to have good agreement with the experimental results reasonably well and was shown to be useful to predict the performance of this particular ELM process under diverse operating conditions.