Mini Review on the Use of Liquid Membran

The current mini-review focuses on the use of liquid membranes in the platinum group metal (PGM/PGMs) extraction from various types of wastewaters to prevent environmental pollution; and for the metal recovery to address the scarcity of the PGMs in the industrial cycles. The bulk liquid membranes have been used to extract PGMs from acidic aqueous media with recoveries of up to 96.3 ± 2.5% of the original PGM amount. The extraction time generally ranges from 2 to 24 hours. The bulk membrane liquid in the PGM extraction will depend on the covalent structure of the extractant, the feed phase PGM concentration and the complex of the PGM in question that is actually extracted from the aqueous environment. The advantages of this type of liquid membrane include its operational simplicity, while the disadvantages include limited possibility to improve the extraction performance of the system. Literature data indicate that extraction of PGMs from mining and metal-refinery side-streams does not suffer from interference from commonly found metal contaminants. Further research should focus on the application of ELM to PGM extraction from wastewaters, emphasizing the use of the Taylor-vortex column and non-Newtonian ELMs. Supported liquid membranes could recover 78-82% of the original PGM content from model side-streams.