Water-in-oil-in-water (W/O/W) emulsion instability in emulsion liquid membrane: Membrane breakage

Abstract

Water-in-oil-in-water (W/O/W) emulsion system in Emulsion liquid Membrane (ELM) consist of three main phases which are membrane phase, internal phase and external phase. However, ELM performance is reported to be heavily affected by the emulsion stability. Instability of emulsions occurred as a result of metastable colloids that are made of two immiscible liquids, where one being dispersed in the other with the presence of surface-active agent. Membrane breakage was identified as one of the causes of emulsion instability. This research work focuses on identifying best condition that records minimal breakage hence, high efficiency of solute removal can be anticipated. Influence of homogenization time and speed, carrier concentration and surfactant concentration on membrane breakage were investigated. Data recorded shows that the emulsion needs to be homogenized at 8000 rpm for 15 mins to obtain minimal breakage of membrane. On top of that, membrane phase consists of 4 wt% of carrier (D2EHPA) and 4 wt% of surfactant (Span 80) dissolved in kerosene is needed. 0.14% of breakage was recorded at the conditions mentioned.