Adsorption Isotherm Models and Kinetics for Chlorpyrifos Adsorption from Aqueous Solutions onto Bottom Ash using Batch Experiments

The ability of activated bottom ash (ABA) to adsorb chlorpyrifos from aqueous solution has been studied through batch experiment. The ABA was characterized by FTIR (Fourier Transform Infrared Spectroscopy) and SEM (Scanning Electron Microscopy). The batch experiment has been performed by varying Contact time, pH, Adsorbate concentration and Adsorbent dose. The adsorption process is found to be pH-dependent, maximum adsorption takes place at pH 2. The adsorption process was relatively moderate, and equilibrium achieved after 120 min of contact time. The adsorption equilibrium data was, then, fitted to Langmuir, Freundlich and Temkin isotherm models one by one to evaluate the mode of adsorption. Experimental results showed that, Langmuir isotherm describes this adsorption process the best. The kinetics of adsorption was further analysed by applying the pseudo-first-order, the pseudo-second-order and the Weber-Morris diffusion model to adsorption data. The kinetic data of this adsorption obeyed pseudo-second-order rate equation.