Removal of Hexavalent Chromium by Membrane-Based Hybrid Processes

Abstract

The presence of the toxic metal Cr(VI) in wastewater is a major concern from an environmental point of view, and its complete removal from waste solutions is a difficult task to accomplish. Membrane-based hybrid processes have been developed to maximize its efficient removal from aqueous wastes. One such process comprises emulsion liquid membrane (ELM) extraction and reduction−precipitation. ELM is a one-step process involving extraction and stripping, simultaneously. The liquid membrane constitutes of an extractant and surfactant dissolved in the organic diluent. The addition of strip phase into the organic phase results in the formation of an emulsion. The selection of surfactant is decisive in the ELM extraction process, as the concentration of the target metal inside the strip phase heavily relies on it. Aqueous waste containing Cr(VI) (300 mg/L) was treated with emulsion to gain higher concentrations of Cr(VI) inside the strip solution in one step. Important parameters affecting the ELM process of Cr...