Separation of valuables from spent selective catalytic reduction catalyst leaching solution by fabricated anion extraction resins

• Published in: Journal of environmental chemical engineering 2018-02, Vol.6 (1), p.1100-1108
• Main Authors: Kim, Joung Woon, Hwang, In-Ju
• Format: Article
• Language: English
• Subjects: Adsorption; Extraction resin; Isotherms; Kinetic model; Recovery; Spent catlaysts
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2017.11.040

Recovery of valuables from spent selective catalytic reduction (SCR) catalysts was carried out in order to increase the TiO2 purity and reduce the environmental impact of landfill. In our previous pressure-leaching studies, the pressure leaching process using an autoclave experienced problems resulting from residual impuries (Na2SiO3). In this study, we conducted experiments using synthetic resins to remove impurities. Glycidyl methacrylate/N,N’-methylenebisacrylamide-grafted methylcellulose beads were synthesized. Leaching solutions from spent SCR catalysts were prepared using the pressure leaching process. W and V were adsorbed onto the synthetic extraction resin, followed by desorption to recover them from separated sodium silicate. Three types of reaction models were used to analyze adsorption/desorption reaction mechanisms (adsorption isotherm, thermodynamics isotherm, and kinetic models). As a result, the adsorption W of was found to be higher than that of V because the ion selectivity of WO42− is higher than that of VO3−. Langmuir and Freundlich isotherm datas included that, adsorption relied on monolayer adsorption mechanisms. According to the Temkin isotherm, experimental W and V adsorption values and calculated Gibbs free energies for both elements were similar. The D-R isotherm, suggested that WO42− followed an ion adsorption mechanism, while some VO3− ions underwent physical adsorption. The Temkin isotherm indicated that both adsorption process (W and V) were endothermic. Pseudo first order and pseudo second order reactions were investigated to compare the theoretically predicted, time-dependent adsorptions to those determined experimentally, the results of which indicate that these adsorptions follow pseudo second order kinetics. WO42− with a higher relatively selectivity, displayed experimental data similar to those obtained theoretically by the adsorption isotherm mechanism.