Diuron Removal from Water by Adsorption: Fundamentals, Mechanism, Desorption, and Future Perspectives

Diuron is a broad-spectrum herbicide used to control weeds and algae in the agriculture sector. Diuron as a water pollutant has been detected in various water bodies due to its slow biodegradation. The adsorption methods offer a promising solution because of their low costs and efficiencies. This article discusses the presence, fate, ecotoxicology, and removal of diuron from aqueous media by adsorption. It was observed that the most effective adsorbents are employed at dosages below 1.0 g L⁻¹ in slightly acidic to neutral solutions (pH 6–7). Pseudo-second-order model describes the best fitting of the adsorption kinetics, while Langmuir isotherm is used for the determination of adsorption capacity. Activated carbon derived from argan nutshells exhibited exceptional adsorption capacity up to 780 mg g⁻¹, followed by activated carbon obtained from cassava biomass with 122 mg g⁻¹ adsorption capacity. It is also observed that increased dissolved oxygen in water enhances diuron removal with carbonaceous adsorbents (above 60% removal); even in the presence of other common pesticides. In fixed-bed systems, rice husk ash shows an adsorption capacity of 9.5 mg g⁻¹. Finally, theoretical results suggest that diuron adsorption occurs through various physical interactions (π-π interactions, H-bonding, dipole-dipole, and van der Waals forces), depending on the adsorbent surface. Diuron removal is well established at the laboratory scale, but further research is needed to bridge the gap between successful lab-scale applications and continuous large-scale applications.