MIL-100(Fe)中乙醇对低挥发性香兰素的协同脱附研究

Synergistic desorption of low volatile vanillin with ethanol on MIL-100(Fe)

提出“高挥发性分子协同脱附”策略,即利用高挥发性乙醇分子与低挥发性香料香兰素分子间的氢键作用,提升香兰素/乙醇MIL-100(Fe)共吸附体系中香兰素分子在MIL-100(Fe)上的脱附效率,并通过分子模拟计算香兰素与乙醇分子间的氢键作用,以及MIL-100(Fe)中香兰素和乙醇之间结合能的影响关系。结果发现:MIL-100(Fe)对香兰素乙醇溶液中的香兰素具有较高的吸附量(780 mg/g),并且将吸附香兰素后MIL-100(Fe)在60℃干燥预处理后,由于乙醇的协同脱附作用使香兰素在MIL-100(Fe)上的脱附效率显著上升,其脱附峰温为190℃。同时,考察不同香兰素吸附量对MIL-100(Fe)上香兰素脱附率的影响,发现香兰素的脱附率随香兰素吸附量的增加呈现先增加后下降的趋势,在吸附量约606 mg/g条件时达到最大脱附率(59.1%)。最后,采用分子模拟计算方法发现香兰素和乙醇之间存在强氢键作用,导致在乙醇存在的条件下香兰素与MIL-100(Fe)之间的结合能从-103.47 kJ/mol下降到-66.58 kJ/mol,使得香兰素分子更容易从MIL-100(Fe)上脱附。

In this work,a novel strategy of“highly volatile molecules synergistic desorption”was proposed,in which hydrogen bonds between highly volatile ethanol molecules and low volatile flavor vanillin molecules played an important role in enhancing the desorption efficiency of vanillin molecules over MIL-100(Fe)in the vanillin/ethanol MIL-100(Fe)co-adsorption system.The existence of a hydrogen bond between vanillin and ethanol was determined by molecular simulation.Similarly,the effect of binding energy between vanillin and ethanol in MIL-100(Fe)was also studied.The results showed that MIL-100(Fe)exhibited a high adsorption capacity(780 mg/g)for vanillin ethanol solution.After drying and pretreatment at 60℃,the desorption efficiency of vanillin over MIL-100(Fe)was significantly increased and the desorption peak temperature was found to be 190℃.Meanwhile,the effect of different vanillin adsorption amount on vanillin desorption rates over MIL-100(Fe)was also investigated.Consequently,the vanillin desorption rate increased first and then decreased with an increase in vanillin adsorption,reaching a maximum desorption rate of 59.1% when the adsorption amount was about 606 mg/g.Finally,the strong hydrogen bonding between vanillin and ethanol was found by molecular simulation calculation,and the binding energy between vanillin and MIL-100(Fe)decreased from-103.47 kJ/mol to-66.58 kJ/mol in the presence of ethanol,which made it easier for vanillin molecules to be desorbed from MIL-100(Fe).