Abstract The kinetics of isothermal extraction of caffeine from guarana seed under the action of ultrasonic field with simultaneous cooling (UESC) was investigated. The isothermal kinetics curves were measured at temperatures range T = 17-58°C. Using the model-fitting method it was determined that the kinetics of caffeine extraction can be described by a theoretical Jander three-dimensional diffusional model. The values of the rate constant were calculated for different temperatures, as well as the kinetic parameters (activation energy (Ea) and pre-exponential factor (lnA)). Based on the results obtained, it is concluded that the rate constants of caffeine extraction under UESC are about 2 times higher in comparison to the values obtained for the extraction in the conditions of conventional heating (CH). The activation energy of the caffeine extraction under the UESC E a UESC = 19.4 kJ ⋅ mo l − 1 $\left( E_{\text{a}}\,^{\text{UESC}}=19.4\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right)$is lower than the values are for CH E a CH = 21.8 kJ ⋅ mo l − 1 . $\left( E_{\text{a}}\,^{\text{CH}}=21.8\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right).$ Energy consumption for UESC is four times lower than for CH conditions. It is shown that there is a linear correlation relationship between kinetic parameters obtained for UESC and CH conditions. The changes in the values of kinetic parameters are explained by the model of selective transfer of energy from the reaction system to the reactant molecules.

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超声波场作用下同时冷却从瓜拉那种子中提取咖啡因的动力学

摘要 研究了超声场同步冷却(UEC)作用下瓜拉那种子中咖啡因的等温提取动力学。等温动力学曲线是在温度范围 T = 17-58°C 下测量的。使用模型拟合方法确定，咖啡因提取的动力学可以通过理论上的 Jander 三维扩散模型来描述。计算不同温度下的速率常数值以及动力学参数（活化能 (Ea) 和指前因子 (lnA)）。根据获得的结果，可以得出结论，与在常规加热 (CH) 条件下提取的值相比，UEC 下咖啡因提取的速率常数高出约 2 倍。UEC下咖啡因提取的活化能 E a UEC = 19.4 kJ ⋅ m l − 1 $\left( E_{\text{a}}\,^{\text{UEC}}=19.4\,\text{ kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right)$ 低于 CH E a CH = 21.8 kJ ⋅ mol − 1 的值。$\left( E_{\text{a}}\,^{\text{CH}}=21.8\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1 }} \right).$ UEC 的能耗比 CH 条件低四倍。结果表明，在 UEC 和 CH 条件下获得的动力学参数之间存在线性相关关系。动力学参数值的变化可以通过能量从反应系统到反应物分子的选择性转移模型来解释。\text{kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right)$ 低于 CH E a CH = 21.8 kJ ⋅ mo l − 1 的值。$\left( E_{\text{a}}\,^{\text{CH}}=21.8\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1 }} \right).$ UEC 的能耗比 CH 条件低四倍。结果表明，在 UEC 和 CH 条件下获得的动力学参数之间存在线性相关关系。动力学参数值的变化可以通过能量从反应系统到反应物分子的选择性转移模型来解释。\text{kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right)$ 低于 CH E a CH = 21.8 kJ ⋅ mo l − 1 的值。$\left( E_{\text{a}}\,^{\text{CH}}=21.8\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1 }} \right).$ UEC 的能耗比 CH 条件低四倍。结果表明，在 UEC 和 CH 条件下获得的动力学参数之间存在线性相关关系。动力学参数值的变化可以通过能量从反应系统到反应物分子的选择性转移模型来解释。结果表明，在 UEC 和 CH 条件下获得的动力学参数之间存在线性相关关系。动力学参数值的变化可以通过能量从反应系统到反应物分子的选择性转移模型来解释。结果表明，在 UEC 和 CH 条件下获得的动力学参数之间存在线性相关关系。动力学参数值的变化可以通过能量从反应系统到反应物分子的选择性转移模型来解释。