Metal oxide-based photocatalysts for the efficient degradation of organic pollutants for a sustainable environment: a review

Abstract

Photocatalytic degradation is a highly efficient technique for eliminating organic pollutants such as antibiotics, organic dyes, toluene, nitrobenzene, cyclohexane, and refinery oil from the environment. The effects of operating conditions, concentrations of contaminants and catalysts, and their impact on the rate of deterioration are the key focuses of this review. This method utilizes light-activated semiconductor catalysts to generate reactive oxygen species that break down contaminants. Modified photocatalysts, such as metal oxides, doped metal oxides, and composite materials, enhance the effectiveness of photocatalytic degradation by improving light absorption and charge separation. Furthermore, operational conditions such as pH, temperature, and light intensity also play a crucial role in enhancing the degradation process. The results indicated that both high pollutant and catalyst concentrations improve the degradation rate up to a threshold, beyond which no significant benefits are observed. The optimal operational conditions were found to significantly enhance photocatalytic efficiency, with a marked increase in degradation rates under ideal settings. Antibiotics and organic dyes generally follow intricate degradation pathways, resulting in the breakdown of these substances into smaller, less detrimental compounds. On the other hand, hydrocarbons such as toluene and cyclohexane, along with nitrobenzene, may necessitate many stages to achieve complete mineralization. Several factors that affect the efficiency of degradation are the characteristics of the photocatalyst, pollutant concentration, light intensity, and the existence of co-catalysts. This approach offers a sustainable alternative for minimizing the amount of organic pollutants present in the environment, contributing to cleaner air and water. Photocatalytic degradation hence holds tremendous potential for remediation of the environment.