Rapid extraction of low concentration heavy metal ions by magnetic fluids in high gradient magnetic separator

A novel method for the extraction of low concentration heavy metal ions from aqueous solution by using magnetic fluids in the high gradient magnetic separator (HGMS) has been constructed. We dissolved the extractant tributyl phosphate (TBP) in the magnetic fluids, and selected the Au3+ as the model of heavy metal ion to research the extraction efficiency of magnetic fluids containing TBP in this article. The magnetic fluids containing TBP, as stationary phase in the form of liquid-droplet, were immobilized on the surface of steel wires in the HGMS; the low concentration Au3+, as mobile phase, flowed through the HGMS and was extracted from aqueous solution. The experiments investigated the dependence of the Au3+ extraction efficiency of magnetic fluids on the pH value of aqueous solution, TBP concentration in magnetic fluids and flow rate of aqueous solution in magnetic separation column. Under the optimum conditions, the proposed method obtained a high extraction capacity and high treatment volume with a continuous extraction process. This method is especially suitable for the extraction of low concentration heavy metal ions solution that was very difficult to be recovered by use of traditional extraction technologies.