Advancing Wastewater Treatment with Sunlight through Cu, Ni, and Cd-Doped nanoCo3O4 for Enhanced Photodegradation and Mineralization.

Co3O4 nanoparticles were purified and modified using chemical precipitation procedures, and doped with Ni, CuNi, and CdNi. The X-ray diffraction study showed that the nanoparticles had a crystallite size of 18 nm and had a cubic crystalline structure. Subsequent doping with nickel, copper–nickel, and cadmium-nickel was conducted to study the modification in the quantum state of the material, specifically examining changes in crystallite size, band gap, and magnetic characteristics. Ni(0.06)Co3O4(0.94) and Cu(0.03)Ni(0.03)Co3O4(0.94) versions showed higher optical band gaps, smaller crystallite sizes, and worse magnetic characteristics compared to undoped CoNPs. The sample Cd(0.03)Ni(0.03)Co3O4(0.94) stood out due to its exceptional magnetic characteristics. Energy Dispersive X-ray Spectroscopy was used to analyze the elemental composition of pure and doped CoNPs. Scanning electron microscopy was employed to examine the morphology, showing that the particles were mostly semi-spherical and had an average size of 32 nm. The nanoparticles’ photocatalytic degradation efficiency was evaluated by measuring the breakdown of Congo red dye in water under exposure to both a Xenon lamp and direct sunlight. This evaluation aims to measure the efficiency of photocatalytic degradation. The doped nanoparticles showed improved degradation abilities, with Cd(0.03)Ni(0.03)Co3O4(0.94) having a high degradation efficiency of 93.4% after 90 min of Xenon radiation. The efficiency was much higher than Cu(0.03)Ni(0.03)Co3O4(0.94) (80.9%), Ni(0.06)Co3O4(0.94) (68.2%), and undoped CoNPs (54%). The photodegradation rate constant for Cd(0.03)Ni(0.03)Co3O4(0.94) is equal to 22.71 × 10−3 S−1 about more than two times of pure CoNPs sample (10.20 × 10−3 S−1), these observation due to the presence of Cd and Ni doping, which have a substantial amount of surface area, and extremely small particle size, this sample was able to attain an optimal bandgap configuration, resulting in an increase in its photocatalytic performance. The photodegradation efficacy of five distinct effluent wastewaters under solar irradiation was meticulously examined. In addition, investigations were conducted into the recycling capabilities of Congo Red dye and effluent wastewater, with the processes being repeated seven and eight times, respectively, to evaluate the sustainability and efficiency of these methodologies in contaminant removal. [ABSTRACT FROM AUTHOR]