Adsorption of polluted dyes from water by transition metal oxides: A review

Water is the source of life on the planet's surface. Water safety has become a crucial requirement for safe drinking water as a result of the increase in activities that can pollute water supplies. Every year, thousands of tons of dyes used in industry are discharged into water. The health and environmental issues brought on by dye pollution make surface water contamination a global issue of the utmost concern. Removal of dyes by adsorption technology is a particularly important technique, because of its usability, simplicity, high efficiency, and scale-up over a wide range of concentrations. Metal oxides are considered among the widely used nanomaterials for environmental control and contaminations removal. Such properties come from their variable oxidation states, large surfaces, and varying electronic configurations. This review focuses on the use of metal oxides in pure form, especially those of the first transition series for the treatment of wastewater from various kinds of organic dyes. Experimental studies were searching for efficient removal of dyes, and providing the suitable removal conditions besides the mechanism of adsorption through the isothermal and kinetic studies.