Review of phenol adsorption on transition metal oxides and other adsorbents

Adsorption technology is widely used to remove specific pollutants from wastewater, including the very problematic group of phenolic compounds. Transition metal oxides are the preferred adsorbent for phenol removal. This review analyzes the recent advances in the adsorptive removal of phenol using transition metal oxides. Here, we review the synthesis and characterization of transition metal oxides with a particular focus on the effects of the synthesis method on the surface functionality and structural and textural properties of transition metal oxides. Moreover, the effects of the adsorption parameters, i.e., solution's pH and phenol's concentration, on the adsorption process are discussed. Finally, an in-depth analysis of the adsorption kinetics and the mechanism is provided.