Benzotriazole removal from water by Zn-Al-O binary metal oxide adsorbent: behavior, kinetics and mechanism

In this study, a novel Zn-Al-O binary metal oxide adsorbent was prepared and used to remove the emerging polar contaminant benzotriazole from water. The adsorption behavior, kinetics and mechanism were systemically studied. Results showed that benzotriazole was rapidly and effectively adsorbed by the adsorbent. Instantaneous adsorption was observed under each studied condition, and the adsorption reached equilibrium within 30 min. High initial benzotriazole concentration enhanced the adsorption. The amount of absorbed benzotriazole increased with increasing adsorbent dosage, but decreased with increasing ionic strength. Solution pH had little effect on benzotriazole adsorption. The adsorption isotherm was consistent with S-type. Langmuir isotherm model fitted the equilibrium data better than Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The maximum monolayer adsorptive capacity of benzotriazole with and without electrolytes was 7.30 mg g(-1) and 9.51 mg g(-1), respectively. Elovich and pseudo-second-order models were most suitable for describing the adsorption kinetics. Interactions between the surface sites of the adsorbent and benzotriazole may be a combination of electrostatic interaction, ion exchange and hydrogen bond.