Application of magnetic extractant for the removal of hexavalent chromium from aqueous solution in high gradient magnetic separator

In this paper, we proposed a simple, rapid and continuous method of solvent extraction for hexavalent chromium from aqueous solution in high gradient magnetic separator. We constructed the theoretical modeling of the extraction and introduced the original so-called “magnetic extractant”. The feasibility of extraction using this method was verified by the experiments. The static force analysis and force balance of the magnetic extractant in separator were studied. The extraction efficiency of magnetic extractant and the porosity in separator were related to the accumulation radius. By the mathematical derivation, the accumulation radius was determined by magnetic susceptibilities of the magnetic extractant, intensity of the background magnetic field and wire radius. The influences of the designs of ferromagnetic filler in separator, types of diluent, pH values of Cr (VI) feed solution, the extractant concentration, flow rate, and temperature of Cr (VI) solution in separator were investigated. The results showed that extraction efficiency increased with the decrease of pH value and flow rate of Cr (VI) aqueous solution, and increased with the increase of TBP concentration and temperature. Under the optimum conditions, the proposed method obtained a high extraction capacity with continuous extraction process of 6 h and 1800 ml Cr (VI) aqueous solution.

► The original so-called magnetic extractant has been explained.
► The theoretical model of the extraction process was established.
► The feasibility was studied by extraction experiments of Cr (VI).
► The optimum conditions of extraction were investigated.
► The method obtained a high extraction capacity with a continuous process.