模拟胃环境下柚皮果胶对亚硝酸根的吸附动力学

以柚子白皮为原料制得果胶,在模拟人体胃环境下进行体外实验,研究柚皮果胶对NO_2~-的吸附效果,并进行动力学分析,同时以市售果胶为对照进行红外光谱分析.结果表明,柚子白皮果胶对NO_2~-的吸附效果与胃环境的pH值、NO_2~-质量浓度、模拟胃蠕动的时间和果胶添加量有关,果胶添加量为0.8g/L,pH值为1.5,NO_2~-质量浓度为30 mg/L,420 min可达吸附平衡,此时柚子白皮果胶对NO_2~-的吸附量为17.65 mg/g,去除率为56.21%.动力学研究表明,颗粒内扩散模型能够较好地拟合柚子白皮果胶对NO_2~-的吸附过程;红外光谱分析表明,O—H以及C=O(羧酸和/或酯)等基团参与了果胶吸附NO_2~-的反应.

Adsorption Kinetics of Pectin from Pomelo Peel on Nitrite in a Simulated Gastric Environment

In this study, pectin was extracted from pomelo peel, and the adsorption effect of pectin on NO₂^- was investigated, followed by a dynamic analysis in an environment of human stomach simulation. Then an infrared spectrometer was used to characterize the adsorption sites on pomelo peel pectin, with commercial pectin as the control. The results indicated that the adsorption of NO₂^- by the white pomelo peel pectin was related to pH of the simulated gastric environment, initial mass concentration of NO₂^-, adsorption time and adsorbent dosage of pectin. An adsorption equilibrium was reached when the adsorbent dosage of pectin was 0.8 g/L, pH of the gastric juice was 1.5, and the initial mass concentration of NO₂^- was 30 mg/L after 420-minute adsorption. Under this optimal circumstance, the adsorption quantity reached 17.65 mg/g, and the removal rate was 56.21%. Kinetic studies showed that the whole adsorption process of white pomelo peel pectin toward NO₂^- was well fitted with the intra-particle diffusion model. The infrared spectrum indicated that O-H and C=O (carboxylic acid and/or ester) were involved in the reaction of NO₂^- adsorption by pectin.