酚醛型吸附树脂对咖啡因和茶碱吸附性能的研究

用静态和动态方法研究了酚醛型吸附树脂JDW-2和DuoliteS-761对咖啡因和茶碱的吸附行为.结果表明,自制树脂JDW-2对咖啡因和茶碱的吸附性能明显优于DuoliteS-761.树脂的比表面积、含水量、酚羟基的含量与吸附关系密切,尽管JDW-2的比表面积比DuoliteS-761小,但前者比后者具有更高的含水量(42%)和酚羟基含量(3.72mmol/g).在静态条件下,JDW-2吸附咖啡因的速率比DuoliteS-761快,JDW-2树脂对咖啡因和茶碱饱和吸附量分别为246和127mg/g干树脂,而DuoliteS-761树脂对它们的吸附量分别为121和53mg/g干树脂;JDW-2和DuoliteS-761吸附咖啡因的初始阶段是粒扩散控制过程;酚醛型吸附树脂等温吸附咖啡因和茶碱的平衡吸附数据符合Langmuir方程.酚醛型吸附树脂吸附咖啡因和茶碱属单分子层吸附.在动态条件下,1mol/LHCl和40%甲醇溶液以1.5BV/h来洗脱吸附咖啡因的JDW-2,在4～5个床体积的洗脱率分别是88%和93%,而1mol/LHCl和80%甲醇溶液以1.5BV/h来洗脱吸附茶碱的JDW-2,在3～4个床体积的洗脱率分别是91%和96%,表明酚醛型吸附树脂具有良好的洗脱性能,用1mol/LHCl和40%(或80%)甲醇溶液作复合洗脱剂从JDW-2中洗脱咖啡因(或茶碱),效

Studies on Sorption Property Forwards Caffeine andTheophylline by Phenolic Resin

The sorption of phenolic resin adsorbents JDW-2(made by ourself) and Duolite S-761 for caffeine and theophylline was studied under static and dymanic conditions in this paper.The experimental results show that the sorption properties of JDW-2 for caffeine and theophylline are superior to that of Duolite S-761. The surface area, the moisture retention and phenolic hydroxyl amount of adsorbents jointly influenced the sorption.Though JDW-2 has a lower surface area than Duolite S-761, the former sorbents has a higher moisture retention(42%) and phenolic hydroxyl amount(3.72 mmol/g) as compared to that of the latter.Finally, we have found that the sorption of caffeine by JDW-2 is faster than that by Duolite S-761 under static conditions, the saturation sorption capacity of JDW-2 for caffeine and theophylline is 246 and 127mg/g dried resin respectively, and that of Duolite S-761 is only 121 and 53 mg/g respectively.Asemi-empirical rate equation adequately fit the sorption rate data of caffeine in the initial period.The sorption mechanism of JDW-2 and Duolite S-761 resins for caffeine was confirmed by the particle-diffusion control of the sorption process in the initial period.The equilibrium sorption data for phenolic resin sorbents/caffeine(or theophylline) systems showed good agreement with the Langmuir isotherm equation.The correlation coefficients are bigger than 0.99.The sorption of caffeine and theophylline therefore is monomolecular sorption.It is clear that the volume of 1mol/Lhydrochloric acid in 40% aqueous methanol at the rate of desorption 1.5BV/h for removing 88% and 93% all the caffeine adsorbed on JDW-2 are 4 and 5BV(bed volume) respectively, and that of 1mol/Lhydrochloric acid in 80% aqueous methanol at the rate of desorption 1.5BV/h for removing 91% and 96% all the theophylline adsorbed on JDW-2 are 3 and 4 BVrespectively under dynamic conditions, which show that phenolic resin adsorbent possesses excellent desorption performance.It is very good to use 1mol/Lhydrochloric acid in 40%(or 80%) aqueous methanol as composite desorption solvent stripping caffeine(or theophylline) from JDW-2.