Synthesis and process parametric effects on the photocatalyst efficiency of CuO nanostructures for decontamination of toxic heavy metal ions

Abstract

Among the various environmental pollutants, wastewater from textile dye industries is a major concern. The textile dye industry's effluents contain complex dyes, organic and inorganic salts, acids, and heavy metals which are difficult to decompose in water as they are resistant to biodegradation. Conventional methods for dye removal are not effective due to the nonbiodegradability of dyes and high solubility in water. Photocatalysis is an advanced oxidation process that is effective at degrading recalcitrant organic contaminants. It produces strong reactive oxidants like oxygen or free radical species (hydroxyl radical, and superoxide anion radical) to degrade pollutants into nontoxic molecules Photocatalysis is proposed to be used in conjunction with other treatment processes, such as biological treatments, to reduce total organic carbon, break down macromolecular organic compounds, increased biodegradability, and to reduce the toxicity of water. Through oxidation or reduction reactions, toxic metal ions are converted into their metallic element state, metal oxides, or their valence to nontoxic or lower toxicity. Therefore, the present review focuses on the CuO nanostructures on photocatalytic reduction of metal ions from aqueous media. The impact of synthesis (material) and their process (catalyst, radiation) including the parameters on the photocatalytic activity is overviewed which is the fundamental, and physical source for magnifying the process. Furthermore, the synthesis and process have been discussed in detail considering their impact on eliminating the toxicity of heavy metal ions.