【摘要】 研究了两种吸附树脂XAD-300和LS-106对阿斯巴甜缩合母液中L-苯丙氨酸(L-Phe)的分离去除规律,吸附等温线均可采用Langmuir和Freundlich方程拟合,吸附热力学参数表明,吸附过程均是自发的放热过程。XAD-300对L-Phe的焓变值和吸附自由能变值更大,表明该树脂对目标有机污染物具有更强的吸附亲和力。两种树脂对L-Phe的吸附动力学曲线均符合拟二级动力学方程,且XAD-300的初始吸附速率更大,这与XAD-300更强的吸附亲和力有关。动态吸附穿透曲线显示,XAD-300和LS-106的动态穿透点分别为44BV和6BV,且前者的穿透吸附量高达1.70mmol/g,约为后者的3倍。采用0.1mmol/L的稀Na OH溶液即可实现XAD-300的彻底再生,L-Phe的脱附率高达99.6%。阿斯巴甜缩合母液中共存的L-天冬氨酸对L-Phe的去除几乎无影响,而共存氯盐对L-Phe的去除略有抑制。XAD-300对L-Phe的强吸附亲和力主要源于其丰富的微孔结构,在吸附中微孔填充机制发挥了主导作用。更多还原

【Abstract】 The removal and separation properties of L-phenylalanine(L-Phe) in aspartame condensation solution from the adsorption resins XAD-300 and LS-106 were compared. Langmuir and Freundlich models both described the isotherm data well. The adsorption thermodynamics parameters indicated that the adsorption processes were both spontaneous and exothermic. The greater value of ΔΗ~Φ and ΔG~Φ of L-Phe onto XAD-300 indicated stronger adsorption affinity between them. The adsorption kinetics curves of L-Phe were fitted well by Pseudo-second-order kinetics and the initial adsorption rate of XAD-300 was higher than that of LS-106, which was related to the stronger adsorption affinity of L-Phe onto XAD-300. Dynamic adsorption results revealed that the breakthrough points of L-Phe onto XAD-300 and LS-106 were 44 BV and 6 BV, respectively, and the breakthrough adsorption amount of XAD-300 was 1.70 mmol/g, about three times greater than that of LS-106. Finally, the loaded L-Phe onto XAD-300 was thoroughtly recycled by 0.1 mmol/L Na OH and 99.6% L-Phe could be recovered. The amount of aspartic acid had no effect on the adsorption of XAD-300, but the coexistence of sodium chloride slightly inhibited the adsorption of L-Phe. The stronger adsorption affinity of XAD-300 was mainly related to its abundant microporous structure, and the microporous filling may be the dominant mechanism.更多还原