Synthesis And Application Of Fumaryl Chloride Crosslinked Cellulose Based Macroporous Resin

In recent years, macroporous resin (MR) has been extensively used in the separation and purification of active ingredients from natural products because of the fast and effective adsorption and desorption properties. The commonly used MR consists mainly of styrenic resin, acrylic resin and acrylamide resin. However, these MR are not easy to regenerate and degrade and may also cause secondary pollution. Hence, the research and development of environmental MR has become a research hotspot.In this paper, a new kind of environmental MR—fumaryl chloride crosslinked cellulose based macroporous resin (FCCMR) is prepared by esterification crosslinking of cellulose in the present of fumaryl chloride crosslinker and the porogenic agent. Meanwhile, FCCMR is characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Automated Surface Area and Pore Size Analyzar (BET), respectively. The mechanism of action between FCCMR and isoflavones or saikosaponin is also studied. The main contents and results are listed as follow:(1) FCCMR was successfully prepared by esterification crosslinking of cellulose in the present of fumaryl chloride crosslinker and the porogenic agent, and characterized by FTIR, SEM and BET, respectively. The characterization results indicated that the esterification reaction between fumaryl chloride and cellulose indeed occurred, pores of different sizes on the surface of FCCMR were formed by crosslinked cellulose, FCCMR was found to contain macroporous structure, and the pore sizes were within the range of100to150nm.(2) The adsorption characteristics of isoflavones by FCCMR were studied by static and dynamic adsorption method. The results of static adsorption studies showed that the kinetic adsorption process could be well described by pseudo-second-order kinetic model, the increase in temperature, initial concentration and oscillation rate could help to enhance the adsorption rate, and intraparticle diffusion was the main rate-determining step in the adsorption process. The adsorption isothermal data were consistent with Langmuir model well within the temperature range from303K to323K, which reflected monolayer adsorption of isoflavones. ΔGθ<0revealed that the adsorption of isoflavones was spontaneous, ΔHθ=53.18KJ/mol illustrated that the adsorption process was endothermic and chemical, ΔSθ=188.63J/(mol·K) demonstrated that the degree of disorder in this adsorption system increased as the adsorption process proceeded, and the spontaneous adsorption process exhibited favorable entropy changes and unfavorable enthalpy change, indicating entropy change was the main driving force for the adsorption of isoflavones by FCCMR. The results of dynamic experiments demonstrated that with the increasing flow rate, the adsorption rate of isoflavones firstly decreased, and then increased, and the adsorption rate of isoflavones also increased with the sample concentration.(3) The adsorption characteristics of saikosaponin by FCCMR were studied by static and dynamic adsorption method. The results of static adsorption studies showed that the adsorption kinetics was found to follow pseudo-second-order kinetic model, and the adsorption rate was controlled by both intraparticle diffusion and liquid film diffusion. Freundlich model fitted the equilibrium data better than Langmuir model, indicating that the adsorption process of saikosaponin was not a simple monolayer adsorption. The values of entropy change and enthalpy change were calculated to be61.89J/(mol-K) and16.93KJ/mol for saikosaponin adsorption respectively, which revealed that the spontaneous adsorption of saikosaponin was mainly driven by the positive entropy change. The results of dynamic experiments demonstrated that the adsorption of saikosaponin was basically saturated when the volume of effluent liquid reached100mL. In addition, the maximum adsorption rate of saikosaponin could be obtained when the sample flow rate was1.0BV/h and the sample concentration was100mg/L, and the pH of sample solution was5.12. During the elution process of saikosaponin, the minimum volume required for eluent was found to be70mL to acquire the optimal elution rate.