弱碱性树脂吸附-解吸苦味酸

考察了水中苦味酸在弱碱性离子交换树脂D301R上的吸附与解吸。研究了吸附热力学、动力学特性及吸附机理。结果表明,树脂在pH=2.7～10.2时,吸附能力最好。等温平衡吸附遵循Freundlich模型。吸附过程为吸热、熵增的自发过程。吸附动力学符合Lagergren准二级速率方程,颗粒内扩散为吸附速率的主要控制步骤,吸附速率常数为7.23×10-5～1.20×10-4g/(mg.min),吸附活化能为19.4 kJ/mol。树脂上吸附的苦味酸可用HNO3+丙酮混合液定量洗脱,洗脱率达99%。静态吸附和脱附的比较结果证实了吸附过程中存在不可逆化学吸附。树脂对苦味酸的吸附主要是通过静电吸附、酸碱络合吸附、氢键吸附等协同作用来完成的。

Adsorption-desorption of picric acid by weaky basic resin

The adsorption and desorption of aqueous picric acid solution onto D301R weaky basic anion exchange resin were investigated. The kinetics, thermodynamics and adsorption mechanism were also studied. The results showed that the maximum adsorption ability of resin occured at pH = 2.7 ~ 10.2. The adsorption of picric acid on the resin obeyed Freundlich isotherm and was a spontaneous, endothermal and entropy increasing process. Kinetic analysis shows that the adsorption reaction could be approximated by a Lagergren pseudo-second-order-rate equation for which the intraparticle diffusion is the rate-controlling process with an adsorption rate constant of 7.23×10^-5 ~ 1.20×10^-4 g/(mg·min) and activity energy of 19.4 kJ/mol. Washout rate of 99% of the picric acid adsorbed on the resin can be eluted with a HNO₃ + acetone solution quantitatively. The comparison of static adsorption and desorption confirmed the presence of irreversible chemical adsorption in the adsorption process. The synergistic interactions by the electrostatic, acid-base complex and hydrogen bonding were the main driving forces of picric acid adsorption on the weaky basic resin.