Electromembrane extraction of heavy metal cations from aqueous media based on flat membrane: method transfer from hollow fiber to flat membrane

Abstract

In the present study, the electromembrane extraction (EME) procedure was used for extraction of heavy metal cations from aqueous samples. Extraction from aqueous solutions was done by means of polypropylene hollow fiber or polypropylene flat membrane. In this procedure, effective parameters such as magnitude of voltage, supported liquid membrane (SLM) solvent, pH of acceptor and donor phases, extraction time and number of extraction cycles, stirring rate and the effect of carrier type and concentration were all optimized. Atomic absorption spectroscopy (AAS) was also used for the quantification of transferred ions in both donor and acceptor phases. The optimized conditions included: applied voltage of 60 V, 1-octanol containing 0.5% v/v bis(2-ethylhexyl)phosphate and 0.5% v/v tris(2-ethylhexyl)phosphate as the best SLM solvent, extraction time of 10 min, stirring rate of 1000 rpm, acceptor phase pH 1.2 (65 mM HCl), donor phase pH 10 and the number of extraction cycles 2. Finally, these optimized conditions were applied for the extraction of free silver ions from a nano-silver suspension sample and the extraction of other cations (Co²⁺, Cu²⁺, Cd²⁺, Zn²⁺) from some real aqueous solutions. The obtained results showed that more than 71.2% of the free ions were extracted from primeval aqueous samples. Moreover, the results indicated that this technique can be used in large-scale extraction of heavy metal cations from aqueous solutions.