Adsorption of picric acid from aqueous solution by the weakly basic adsorbent Amberlite IRA-67

Abstract

The presence of nitrophenols in wastewater is of great environmental concern. Therefore, it is important to separate picric acid from wastewater streams. In this study, adsorption of picric acid was studied from aqueous solutions by using a weakly basic adsorbent (Amberlite IRA-67) at three different temperatures (298 K, 308 K, and 318 K). Adsorption of picric acid was investigated in terms of equilibrium, kinetics, and thermodynamic conditions. In the equilibrium studies, 1.00 g of Amberlite IRA-67 was determined as the optimal amount. The most used isotherms, Freundlich and Langmuir, were applied to the experimental data. The Langmuir isotherm gave good results with R squared values over 0.99 at different temperatures. In the kinetic studies, pseudofirst- and pseudosecond-order models and the Elovich equation were applied to the kinetic experiments. The pseudosecond-order model was fitted to this adsorption system with an R squared value of 0.996. In the thermodynamic studies, ΔHads0 = -21.204 kJ·mol-1, ΔSads0 = -200.043 J·mol-1·K-1, and ΔGads0 for different temperatures were calculated. © 2010 American Chemical Society. © 2010 Elsevier B.V., All rights reserved.