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运用程序升温脱附(TPD)实验测定了大马酮、γ-壬内酯、乙基香兰素、乙基麦芽酚和乙酸乙酯五种香气分子在活性炭上的脱附曲线,并根据实验数据计算香气分子在活性炭上的脱附活化能.结合香气分子的偶极矩和分子直径大小,分析五种香气分子的物性对其与活性炭表面吸附作用力(脱附活化能)强弱关系.结果表明:大马酮、γ-壬内酯、乙基香兰素、乙基麦芽酚和乙酸乙酯在活性炭表面上的脱附活化能分别是57.92,55.70,54.41,49.83和46.34kJ/mol.香气分子的直径大小顺序为:大马酮>γ-壬内酯>乙基香兰素>乙基麦芽酚>乙酸乙酯,分子直径大者,其脱附活化能就更大.而这些香气分子的极性大小与其脱附活化能未能形成单调增大或单调减少的关系,表明其极性大小在这些分子与活性炭表面的形成相互结合力方面未能起到主导作用.
The desorption curves of five kinds of aroma molecules of damascenone, γ-nonalactone, ethyl vanillin, ethyl maltol and ethyl acetate on activated carbon were determined by the program of temperature-programmed desorption (TPD). According to the experiment Data were used to calculate the activation energy of the desorption of aroma molecules on activated carbon.The relationship between the physical properties of the five aroma molecules and the adsorption force on the surface of activated carbon (desorption activation energy) was analyzed based on the dipole moment and the molecular diameter of the aroma molecules. The results showed that the activation energy of desorption of damascenone, γ-nonalactone, ethyl vanillin, ethyl maltol and ethyl acetate on activated carbon surface were 57.92, 55.70, 54.41, 49.83 and 46.34 kJ / mol . The order of the diameter of the aroma molecules is: Damascone> γ-nonalactone> Ethyl vanillin> Ethyl maltol> Ethyl acetate, the larger the molecular diameter, the greater the activation energy of desorption. The relationship between the polarity of the aroma molecule and its activation energy for desorption did not increase monotonically or monotonically, indicating that the polarity of the aroma molecule did not play a dominant role in the formation of intermolecular bonding between these molecules and the activated carbon surface.