不同吸附模式对As(V)在TiO2颗粒上亚稳态吸附的影响

通过对比As(V)在TiO₂颗粒上的柱(column)吸附和静态(batch)吸附行为, 研究了柱吸附和静态吸附两种反应模式对该体系亚稳态吸附的影响. 在相同热力学条件下, 将总量一定的As(V)溶液分别加入柱吸附和静态吸附体系中. 结果表明, 随着吸附模式的改变, 静态吸附体系比柱吸附体系更快达到吸附平衡, 静态吸附体系平衡吸附量(0.42 mg·g^-1)明显高于柱吸附体系平衡吸附量(0.25 mg·g^-1), 且静态吸附体系的吸附不可逆性弱于柱吸附体系的吸附不可逆性. 说明溶质吸附模式(动力学条件)的改变使得相同热力学条件下的吸附反应达到了不同的平衡状态. 柱吸附和静态吸附实验中, As(V)在TiO₂颗粒上的液膜扩散系数、总传质系数及吸附平衡后形成的微观吸附状态均不同, 共同导致了两种反应宏观吸附行为上的差异.

Influence of Adsorption Mode on Metastable-Equilibrium Adsorption of As(V) on TiO2 Particles

Column and batch adsorptions of As(V) on TiO₂ particles were conducted to investigate the influence of adsorption mode on metastable-equilibrium adsorption. Under the same thermodynamic conditions, a fixed amount of As(V) was added to both column and batch adsorption systems. Batch adsorption achieved equilibrium more quickly than column adsorption, and the equilibrated adsorption capacity of 0.42 mg·g^-1 for the batch adsorption system was considerably greater than 0.25 mg·g^-1 determined for the column adsorption system. Moreover, the adsorption irreversibility of the batch adsorption system was weaker than that of the column adsorption system. This indicated that the change of adsorption reaction mode (i.e., kinetic processes) could result in different metastable-equilibrium adsorption states under the same thermodynamic conditions. The discrepancy of adsorption behavior between column and batch adsorption systems should be caused by their different liquid film diffusion coefficients and total mass transfer coefficients, as well as different microscopic metastable-equilibrium adsorption states.