Recovery of chromique ions from aqueous effluents by liquid membrane in continuous mode

During the last two decades, an increased interest has been shown in trace elements in water. Metals trace play an important part in the natural geochemical cycles in water. The natural cycles are also affected by metals, particularly in the industrialised part of the world. The requirement for a world with minimum pollution has brought about the need for clean technologies in industrial production. A way to accomplish this could be the recovery and recycling of substances not used in industrial cycles. Chromium is an important material used in a number of industries. It finds use in stainless and alloy steels, pigments, tanning agents. In environmental samples, chromium mainly occurs as chromium (III) or chromium (VI). Chromium (III), which is an essential trace element, is not toxic. In contrast, chromium (VI) is highly carcinogenic and mutagenic. Therefore, it is necessary for risk assessment to determine chromium in its oxidation state (VI) and to concentrate it in order to recycle. For this purpose many different methods have been described: ultrafiltration, ion exchange resin, supported liquid membranes [1]. In this work a method using a liquid membrane is described. Results obtained in continuous flow are presented.

The extraction of Cr(VI) from diluted aqueous effluents, which poses an environmental problem, needs the utilisation of a liquid membrane. The feasibility of Cr(VI) solutions concentration has been studied. The preliminary experiments in continuous mode were performed with the observation that the recovery and concentration of chromium from aqueous solutions were possible. Different Cr(VI) concentrations and flow rates would confirm these results.