Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
581497 | Journal of Hazardous Materials | 2009 | 10 Pages |
Abstract
The three-parameter Sips adsorption model was successfully employed to modeled equilibrium adsorption data of a yellow and a red dye onto a mesoporous aminopropyl-silica, in the presence of the surfactant sodium dodecylbenzenesulfonate (DBS) from 25 to 55 °C. The results were evaluated in relation to the previously reported surface tension measurements. The presence of curvatures of the vanÌt Hoff plots suggested the presence of non-zero heat capacities terms (ÎadsCp). For the yellow dye, it is observed that the values of ÎadsH are almost all positive and they decrease in endothermicity, in the absence and in the presence of DBS, from 25 to 55 °C. For the red dye, there is an increase in endothermicity in relation to the temperature increase. The negative ÎadsG values indicate spontaneous adsorption processes. Almost all adsorption entropy values (ÎadsS) were positive. This suggests that entropy is a driving force of adsorption. The adsorption thermodynamic parameters were also evaluated using a new 23 full factorial design analysis. The multivariate polynomial modelings indicated that the thermodynamic parameters are also affected by important interactive effects of the experimental factors and not by the temperature changes alone.
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Authors
Antonio R. Cestari, Eunice F.S. Vieira, Gláucia S. Vieira, Luiz P. da Costa, Andréa M.G. Tavares, Watson Loh, Claudio Airoldi,