Modeling and Performance Prediction of Chromate Reduction by Iron Oxide Coated Sand in Adsorber Reactors

Iron oxide coated sand (IOCS) as an adsorbent medium for removing hexavalent chromium (Cr(VI)) from industrial wastewater, as well as in permeable reactive barriers for remediation of Cr(VI) in aquifers is investigated in this study. An important feature was the use of a mathematical model for performance forecasting and process upscaling of IOCS fixed-bed adsorber systems for Cr(VI) removal. Another significance aspect was the elucidation of IOCS surface mechanisms and interactions responsible for Cr(VI) sorption and reduction to the less toxic Cr(III). The adsorption equilibrium and mass-transfer parameters for modeling were obtained from independent laboratory studies. Adsorber studies validated the predictive model and established the effectiveness of IOCS for Cr(VI) removal under different conditions. Model simulation studies demonstrated that adsorbent capacity, surface diffusion, and film transfer significantly influenced process dynamics. The study showed that IOCS can be used to remove Cr(VI) from contaminated waters, meeting the overall objectives of regulatory agencies. (C) 2016 American Institute of Chemical Engineers AIChE J, 62: 3717-3729, 2016