Inferring the favorable adsorption level and the concurrent multi-stage process with the Freundlich constant

This paper proposes a method for inferring a favorable level for the adsorption isotherm curve with the Freundlich constant (1/n), explains that a favorable level is only a function of 1/n, and then, five favorable levels are classified according to 1/n value. The adsorbent consumption ratio of the concurrent multi-stage to single-stage system was deduced in order to investigate the relationship between favorable level and the most suitable number of stages. Activated carbon (TGBAC) was prepared from Taiwan Giant Bamboo with steam activation. The isotherm equilibrium of the adsorption of three phenols (phenol, 3-CP, and 4-CP), two dyes (MB and BB 69), and tannic acid on TGBAC was obtained. According to the Freundlich constant (1/n), the adsorption of MB was inferred in a strongly favorable zone. The favorable zone for BB69, phenol, 3-CP, and 4-CP was determined. The tannic acid, the pseudo-linear zone and their most suitable number of stages were also determined. The 1/n values and favorable levels summarized from more than a hundred sources/studies indicate that the favorable levels of the adsorption of dyes and phenols on TGBAC are excellent. This paper proposes a simple method for inferring the favorable level and the most suitable number of stages for the concurrent multi-stage adsorption system. (C) 2007 Elsevier B.V. All rights reserved.