A new study on removal of cadmium by hybrid emulsion liquid membrane

A new application of hybrid emulsion liquid membrane, in which an O/W emulsion phase is placed between two supporting membranes, is applied in the present research for removal of cadmium from aqueous phase. The new setting has advantages such as higher stability of the emulsion phase, lower pollution of feed and stripping phases due to contacting with the membrane phase and higher removal capacity. Trioctylamine has been used as a carrier in the organic phase of the emulsion, while the applied surfactant is nonyl phenol ethoxylate. The effect of different parameters is investigated, such as pHs of aqueous and dispersed phases, organic to aqueous volume ratio in the emulsion, carrier concentration, temperature, stirring intensity and cadmium concentration in the feed phase on the performance of the system. The appropriate values of pH for stripping phase and the emulsion's aqueous phase are found to be about 13 and 7, respectively. The optimum organic to aqueous phase volume ratio in emulsion is found to be about 1. The removal efficiency increases approximately twice when the emulsion is stirred more rigorously. Applying the new setup can enhance the removal capacity comparing to the ultimate capacity obtained from the hybrid liquid membrane system.