Impedance spectroscopy of solids for monitoring the adsorption kinetic of chromate ions from aqueous solution by a synthesized clay

Abstract

The adsorption kinetic of chromate ions from aqueous solution was monitored by analyzing the electrical response of the adsorbent at various contact times. This process was also monitored by XRD and FTIR which confirmed the retention of chromate ions on the absorbent surface. The adsorbent used was a synthesized clay based on nitrate intercalated magnesium–aluminum layered double hydroxide (LDH). The adsorption kinetic of chromates was found to follow a pseudo-second order model. Through the contact time dependence, it was found a good correlation between the adsorbed quantity of chromates and the electrode-sample interface conductivity of the adsorbent, which showed a quasi-symmetry achieved by a plateau leading to a same equilibrium time of 60 min. A similar result was observed for the percentage removal of chromates and the relative change in capacitance of the electrode-sample interface of the adsorbent that exhibited a same maximum rate of approximately 93 %.