Adsorption equilibria of formic acid by weakly basic adsorbent Amberlite IRA-67: Equilibrium, kinetics, thermodynamic

Formic acid is an important chemical and biochemical compound used in various industries. It is important to separate this acid from wastewater streams. In this study, adsorption of formic acid was studied from aqueous solution by using weakly basic adsorbent (Amberlite IRA-67) at three different temperatures (298K, 318 K, and 328 K). Adsorption of formic acid was investigated in terms of equilibrium, kinetics and thermodynamic conditions. Optimal amount of IRA-67 was determined as 1.00 g. The most used isotherms, Freundlich and Langmuir, were applied to experimental data. Langmuir isotherm gave good results with R-2 value over 0.99 at different temperatures. Pseudo-second-order model was fitted for this adsorption system. Thermodynamic parameters, Delta H-ads degrees, Delta S-ads degrees and Delta G(ads)degrees, were calculated. (C) 2009 Elsevier B.V. All rights reserved.