Phenolic compounds removal from aqueous solution by composite of alumina-zirconia

Abstract

ABSTRACT Recently, composite of metal oxide has continually elicited tremendous attention from research scientist globally as a viable adsorbent for the removal of phenol and its derivative from aqueous media owing to their improved physicochemical structures which enhanced adsorption capacity. In this study, a composite of alumina-zirconia (Al2O3–ZrO2) was synthesised by calcination techniques and characterised using scanning electron microscopy–energy dispersive X-ray Spectroscopy (SEM-EDX), and X-ray diffraction (XRD). Results from characterisation revealed the formation of this composite with amorphous structure. The composite was employed to evaluate the performance removal of phenol and 2,4-dichlorophenol from solutions using the batch adsorption technique by considering the influence of varying solution pH, initial concentration, adsorbent dosage, contact time and temperature. The optimal conditions predicted from the study are pH of 7 and 8 at a contact time of 90 minutes for phenol and 120 minutes for 2,4-dichlorophenol, respectively, at a temperature of 301 K. The isothermic empirical models of Langmuir, Freundlich and and Dubinin-Radushkevich were employed. The Freundlich model best described the adsorption process with R 2 correlation values (0.945–0.998). The pseudo-second-order kinetics model adequately depicted the rate of adsorption with higher correlation values (≥0.99) for both compounds as compared to the pseudo-first order. The thermodynamic parameters computed suggest non-spontaneous, exothermic reaction and decreased randomness. The study portends the composite Al2O3–ZrO2 composite to be viable for removal of phenolic compounds from wastewater.