Removal of Cr(VI), Mo(VI), and V(V) Ions from Single Metal Aqueous Solutions by Sorption or Nanofiltration

The removal of Cr(VI), Mo(VI), or V(V) anions from single metal aqueous solutions was studied. Two alternative treatment methods were applied: (1) sorption of these anions onto commercially available akaganeite (β-FeOOH) or (2) nanofiltration, using a commercial spiral-wound pilot-scale unit. During sorption experiments, kinetics and equilibrium were mainly studied. A modified second-order kinetic model was found to better fit the kinetic results. Freundlich isotherms better described (slightly) chromium and molybdenum equilibrium sorption experiments; whereas Langmuir isotherm better described vanadium equilibrium. During nanofiltration experiments, the influence of pH and of initial anion concentration was mainly studied, using a fixed background electrolyte concentration. Keywords: AkaganeiteRemovalAnionsSorptionNanofiltrationChromiumMolybdenumVanadium Acknowledgments Thanks are due to the Greek State Scholarship Organization (IKY) for financing this common research in the framework of Greek–German cooperation project (IKYDA), as well as to Dr. Ernst for experimental collaboration with the membrane experiments.