Emulsion liquid membranes disadvantages

Although microemulsions offer many potential advantages when used as emulsion liquid membranes, their effective usefulness in an industrial setting is questionable. Studies on a variety of systems have shown some disadvantages of microemulsions as opposed to coarse emulsions ... 

In spite of these disadvantages emulsion liquid membranes have been widely studied in terms of combinations of extractant and emulsifier. The process has also been piloted for the recovery of zinc from rayon spinning waste liquor. 

Summary of Significant Shortcomings. The emulsion liquid membranes studied each possess advantages when compared against one another. In specific, the microemulsion systems displayed separation kinetics which were typically an order of magnitude faster than the macroemulsion counterparts. However, tlm increased rate of separation was at the expense of product recovery. The concentrated mercury was easily recovered by electrostatic demulsification for the macroemulsion system, but required the addition of butanol to the microemulsion before mercury recovery was achieved. The requirement of chemical demulsification is a major disadvantage of the microemulsion-based liquid membrane system. 

The advantages and disadvantages of membrane based processes and pertraction through various types of liquid membranes are summarized in Table 23.5. HF contactors are supposed in these processes with the exception of pertraction into stable emulsions (ELM) where mixed column contactors or mixer-settlers are used. 

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