2,4-二羟基苯甲酸在3种树脂上的吸附特性

Adsorption Properties of 2,4-Dihydroxybenzoic Acid on Three Anion Exchange Resins

通过静态和动态吸附实验,研究了717(凝胶型,强碱)、D201(大孔型,强碱)和D301R(大孔型,弱碱)3种阴离子交换树脂对水溶液中2,4-二羟基苯甲酸的吸附特性.结果表明,717和D201在pH4～11时、D301R在pH3～9时吸附能力最好.在pH=5及温度293～313K、初始浓度0.6488～6.488mmol/L条件下,D301R,717和D201对2,4-二羟基苯甲酸的等温吸附规律均符合Freundlich模型,最大平衡吸附量分别为2.98,2.66和2.54mmol/g(吸附未达饱和),均为物理性自发吸附的放热过程.动力学实验数据用准一级模型方程拟合比准二级更接近实验值.5%(ω)NaCl+2%(ω)NaOH脱附液100mL均可有效洗脱3种树脂上吸附的2,4-二羟基苯甲酸,脱附率达99%.相同条件下,D301R树脂对2,4-二羟基苯甲酸的吸附性能优于D201和717树脂.

The adsorption properties of 2,4-dihydroxybenzoic acid by 717 （gel-type, strong base）, D201 （macroporous-type, strong base） and D301R （macroporous-type, weak base） resins were studied through static and dynamic experiments. The results show that the maximum adsorption ability of 717 and D201 resins occurs at pH=4-11, and D301R resin at pH=3-9. At pH=5, 293-313 K and initial concentration of 2,4-dihydroxybenzoic acid of 0.648 8-6.488 mmol/L, the adsorption isotherms of 2,4-dihydroxybenzoic acid on D301 R, 717 and D201 resins obey Freundlich model, and their maximum equilibrium adsorption capacity is 2.98, 2.66 and 2.54 mmol/g, respectively （the adsorption has not reached saturation yet）. The adsorptions are physical and spontaneous, exothermal processes. Pseudo first-order and pseudo second-order models were applied to correlate the kinetic experimental data. The former was more accordant with the experimental data than the latter. The 2,4-dihydroxybenzoic acid adsorbed on the three resins could be eluted by 100 mL 5%（ω） NaCl＋2%（og） NaOH solution quickly with elution rate reaching 99%. The adsorption performance of 2,4-dihydroxybenzoic acid on D301R resin was better than on that on D201 and 717 resins under the same conditions.