2,4-二羟基苯甲酸在3种树脂上的吸附特性

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pH 4~11时、D301R在pH 3~9时吸附能力最好. 在pH=5及温度293~313 K、初始浓度0.6488~6.488 mmol/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2.54 mmol/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%(w) NaCl+2%(w) NaOH脱附液100 mL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.

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

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 0.6488～6.488 mmol/L,the adsorption isotherms of 2,4-dihydroxybenzoic acid on D301R,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%(ω) 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.