Adsorptive Separation Of Fructose And Glucose On Metal Organic Frameworks

Fructose and glucose are two important isomers in sugar industry and green energy industry.The general method of separating these two saccharides is adsorptive process.Therefore,development of new adsorbents is an important research field of fructose and glucose separation.Metal-organic frameworks(MOFs)are a series of porous materials with high specific surface and porous structure,which have already found applications in liquid phase adsorption.In this study,the adsorptive separation performances of seven MOFs were investigated.In this study,seven water-stable metal-organic frameworks [UiO-66,ZIF-8,MIL-101(Cr),MIL-100(Cr),MIL-53(Cr),MIL-96(Al),MIL-100(Fe)] were successfully synthesized,and the structures of these seven MOFs were confirmed by various characterizations.All of seven MOFs were studied on adsorptive capacities of fructose and glucose from aqueous solution.UiO-66 exhibited better performance in adsorption capacity and selective adsorption of fructose.The separation factor of fructose and glucose adsorption on UiO-66 is 3.50,which is higher than reported classical adsorbents like ion-exchange resins and zeolites.The adsorptive process with UiO-66 was further investigated in detail including kinetic,isotherm and adsorption mechanism.The results showed that the adsorption would reach equilibrium in 4 hours.The kinetic analysis suggested that the adsorption rate was controlled by both film diffusion and intraparticle diffusion.The adsorption of fructose and glucose on UiO-66 could also be described by the pseudo-second-order model.The better fitting of Freundlich model than Langmuir model indicated a multilayer adsorption on heterogeneous surface.The thermodynamic parameters(?G,?H and ?S)were calculated,indicating that the adsorption was an endothermic process with increase of entropy.At last,the adsorbed UiO-66 was regenerated by washing with deionized water and ethanol.After three times,the separation ability of regenerated UiO-66 did not decrease remarkably,so the stability of UiO-66 was confirmed.All the results suggested that UiO-66 is a promising adsorbent for adsorptive separation of fructose and glucose.