Adsorptive Separation of Fructose and Glucose by Metal–Organic Frameworks: Equilibrium, Kinetic, Thermodynamic, and Adsorption Mechanism Studies

In this work, seven metal–organic frameworks [ZIF-8, MIL-53(Cr), MIL-96(Al), MIL-100(Cr), MIL-100(Fe), MIL-101(Cr), and UiO-66 ] were applied for adsorptive separation of fructose–glucose mixture. UiO-66 exhibited better performance in adsorption capacity and selective adsorption of fructose. The adsorptive process with UiO-66 was further investigated in detail including kinetic, isotherm, and adsorption mechanisms. The rate-determining step analysis based on film diffusion and intraparticle diffusion model suggested that the adsorption process was controlled by multiple steps, which fitted the pseudo-second-order model. The Freundlich model was fitting better than the Langmuir model, which indicated multilayer adsorption on heterogeneous surface. The thermodynamic parameters (ΔG, ΔH, and ΔS) were calculated, indicating that adsorption process on UiO-66 was an endothermic and entropy increment process. UiO-66 can be a promising adsorbent for adsorptive separation of fructose and glucose.