Kinetic and thermodynamic adsorption study of formic and acetic acids from aqueous solution by activated carbon derived from moringa oleifera pods

Abstract

Abstract Adsorption of formic acid (FA) and acetic acid (AA) from aqueous solution by moringa oleifera pods activated carbon (MP-AC) were investigated due to their toxic effect in aquatic medium. The MP-AC was characterized for the following parameters: Bulk Density, Moisture Content, Ash Content, pH, Scanning Electron Microscopy (SEM) and Fourier Transform Infra-Red Spectroscopy (FTIR). Batch experiment was adopted and the adsorption equilibria of AA and FA onto MP-AC were investigated by potentiometric titration method. The effects of initial concentration, agitation time, adsorbent dosage and temperature were also investigated. The experimental data were analyzed with some Isotherm models. It was found that Langmuir model adequately described the adsorption of FA onto MP-AC. Temkin, Freundlich and Dubinin-Radushkevich (D-R) Isotherm models better described the adsorption of AA onto MP-AC. The Kinetic data were examined and the Pseudo-Second-Order kinetic model agreed most and was found to adequately explain the adsorption kinetic of the adsorbates. Thermodynamic parameters showed that the adsorption of FA was spontaneous while that of AA was non-spontaneous. The adsorption processes were exothermic.