An experimental study on removal cadmium from wastewater by emulsion liquid membrane

Research was conducted on cadmium, a heavy metal pollutant, extraction out of wastewater by means of an emulsion liquid membrane system. The emulsion liquid membrane was made of a carrier (di(2-ethylhexyl) phosphoric acid), a surfactant (ECA 4360J), and a stripping agent (sulfuric acid). The effects of using the following parameters on the membrane to optimize the operating conditions were investigated: type of buffer solutions, initial external phase pH, initial cadmium concentration, internal sulfuric acid concentration, impeller stirring speed, carrier concentration, surfactant concentration, and selectivity between cadmium and sodium ion. The best performance for the system presented in this thesis was: The buffer solution is sodium phosphate with citric acid. The pH in the external phase should be maintained between 4-5. Those concentrations in the membrane should be: 3 wt % carrier and 3 wt % surfactant. The internal stripping agent is 6M sulfuric acid and the impeller stirring rate is 300 rpm. The ratio of the membrane phase to the internal phase is 82:18. Under these conditions, a single stage extraction performance of 98% is obtained within thirty minutes