阴离子交换树脂吸附辣椒碱的动力学研究

Adsorption Kinetics of Capsaicin on Anion Exchange Resin

以辣椒树脂为原料,采用静态吸附法确定了201×7型阴离子交换树脂吸附辣椒碱的最优工艺和提取机理。通过可见分光光度法测定了辣椒碱的质量浓度,并绘制出了不同pH的吸附等温线,建立了离子交换吸附辣椒碱的动力学模型。实验结果表明：该树脂吸附辣椒碱的最优pH值为5.5,当pH〈5.0或pH〉6.0时,Langmuir方程能够更好地拟合该吸附过程;而当pH=5.0-6.0时,辣椒碱的吸附等温线更符合Freundlich方程。在pH=5.5、308.15K下,较高的辣椒树脂的质量浓度能显著提高离子交换速率,且初期（t〈30 min）800-1200r/min的搅拌速率有利于吸附过程。通过计算得出,树脂吸附辣椒碱模型的速率常数k0=2.11×10-3s-1、活化能Ea=12.6 k J/mol、反应级数为0.268,并利用Freundlich模型解析获得了最优pH值（5.5）下阴离子交换树脂吸附辣椒碱的动力学方程。

The capsicum resin was used as raw materials to investigate the optimal technology and mechanism of capsaicin adsorption on 201 × 7 anion exchange resin by static adsorption method. The concentration of capsaicin was detected by visible spectrophotometry, and the adsorption isotherms at different pH value were obtained. The adsorption kinetics model of capsaicin on ion exchange resin was also established. Experimental results indicated that the optimal pH value of capsaicin adsorption was 5.5, and the Langmuir equation was more suitable for the adsorption process when the pH value was lower than 5.0 or higher than 6.0. The adsorption isotherms of capsaicin were in accordance with Freundlich equation when the pH value ranged between 5.0 and 6.0. At pH =5.5 and 308. 15K,larger mass concentration of capsicum resin would increase significantly ion exchange rate. Moreover, the stirring speed within 800 r/min - 1 200 r/min could favor the adsorption process at the initial stage （ 〈 30 min）. By calculation, the adsorption rate constant, apparent activation energy and reaction order were k0 = 2. 11 × 10^-3 s^-1, Ea = 12.6 kJ/mol and a = 0. 268, respectively. The kinetics equation for capsaicin adsorption on anion exchange resin was achieved at pH = 5.5 through Freundlich model.