Adsorption of two coffee aromas from synthetic aqueous solution onto granular activated carbon derived from coconut husks

Soluble coffee production requires several processes that cause the loss and degradation of aromas, which reduces the quality of the final product. However, such aromas can be recovered into aqueous solution during the production process. Aromas must be separated from water, and pleasant compounds, such as benzaldehyde, must be separated from unpleasant compounds, such as acetic acid. In this study, the kinetic and thermodynamic parameters of benzaldehyde and acetic acid adsorption from synthetic single-solute aqueous systems onto commercial grade granular activated carbon derived from coconut husks were investigated. The contact time required to attain adsorption equilibrium of benzaldehyde was 6 h, while that of acetic acid was 10 h. Adsorption isotherm data revealed that the adsorption of benzaldehyde and acetic acid was exothermic and spontaneous in nature. Moreover, the isosteric heat of adsorption indicated that the adsorbent surface was energetically heterogeneous. The adsorption equilibrium was fitted according to Langmuir, Freundlich and Temkin isotherms. (C) 2010 Elsevier Ltd. All rights reserved.