Influence of adsorption mode on metastable-equilibrium adsorption of as(V) on TiO2 particles

Abstract

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. © Editorial office of Acta Physico-Chimica Sinica.