Photocatalytic Activity of Metal-Doped MgO Nanoparticles for Dye Removal with Cost Estimation

Metal-doping is a technique used to modify the surface, crystalline, textural, and/or optical properties of the photocatalytic semiconductors, giving greater photocatalytic degradation performances. In this study, a MgO semiconductor catalyst material was doped using copper (Cu) (3% wt) and zinc (Zn) (3% wt), respectively, via a simple co-precipitation synthesis technique. The synthesized 3% Cu-MgO and 3% Zn-MgO were then tested for the photocatalytic degradation of methylene blue dye (MB) as a model pollutant under neutral pH for 120 min. The catalyst dosage used was 500 ppm and the initial MB concentration was maintained at 11 ppm in both cases. After 120 min, the 3% Zn-MgO revealed a 68.85 ± 2.31% MB degradation efficiency, whereas the 3% Cu-MgO revealed a 63.91 ± 2.17% MB removal efficiency. Moreover, the synthesized pure MgO material was also employed for the photocatalytic degradation of MB under the same conditions (as a control), revealing only a 41.12 ± 1.34% MB removal efficiency. These MB removal efficiencies suggest the importance of metal-doping in improving the photocatalytic degradation process. Moreover, the unit treatment cost of MB solution using the proposed photocatalytic process reached $7.95/m3. This study directly addressed UN SDG 6 “Clean Water and Sanitation” and 14 “Life below water” through the conservation of the marine environment by effectively treating wastewater prior to its exposure to the marine environment.