Sorption Kinetics, Thermodynamics and Regeneration for Lipid Feedstock Deacidification Using a Mixed-Bed Ion-Exchange Resin

Abstract

This research investigated adsorptive deacidification of lipid feedstocks using Dowex monosphere MR-450 UPW mixed-bed resin (Sigma-Aldrich, St. Louis, MO). The impact of temperature, mixing and feedstock moisture content on deacidification kinetics is reported. Resin reusability and deacidification of multiple feedstocks was examined. Our results demonstrated that deacidification using the resin followed Lagergren's pseudo first-order reaction kinetics with a rate constant of 1.352/min under the most favorable reaction conditions (50C, 0% moisture content and 550 rpm mixing rate). Gibb's free energy of the reaction increased from −2.81 kJ/mol at 298 K to −12.17 kJ/mol at 323 K, demonstrating the impact of temperature on deacidification. Resin regeneration with methanol-based rinses resulted in at least 40% feedstock deacidification after three wash cycles. Collectively, our research results demonstrate the promise of using heterogeneous gel-type resins for deacidification of a wide range of feedstocks and edible oils with a high percentage of free fatty acid and/or impurities. Practical Applications Dowex monosphere MR-450 UPW mixed-bed gelular ion-exchange resin is effectively used for adsorptive deacidification of high fatty acid oils in the absence of alcohol at low reaction temperatures (<60C). The ion-exchange resin surfaces are regenerated with solvent washing and reused for deacidification over multiple cycles.