CaAl1.5Fe0.5O4/6%Ni-ZnO nanocomposites: Synthesis, characterization and effective photocatalyst for the photocatalytic degradation of methylene blue dye

• Synthesis of CaAl1.5Fe0.5O4/6%Ni-ZnO nanocomposites by microwave (MW) combustion method. • Characterization using XRD, SEM, FT-IR, TEM, BET, Mott-Schottky and UV-DRS analysis. • Photocatalytic degradation (96 %) of Methylene Blue dye using CaAl1.5Fe0.5O4/6%Ni-ZnO in 120 min. • The mechanism of CaAl1.5Fe0.5O4/6%Ni-ZnO photocatalyst degradation of dyes was deduced. This study focuses on synthesizing and analyzing properties of calcium aluminate photocatalytic nanoparticles using the microwave (MW) combustion method by following the rules of green chemistry and investigates their effectiveness in the adsorption of methylene blue (MB) dye which is a crucial contaminant that enters water resources. The synthesized nanoparticles, including CaAl 2 O 4 (CAO), CaAl 1.5 Fe 0.5 O 4 (CAFO), 6 %Ni-ZnO (NZO), and CaAl 1.5 Fe 0.5 O 4 /6%Ni-ZnO (CAFONZO) composites, were characterized using various techniques. XRD analysis confirmed the formation of spinel structures in all samples. The crystallite size and lattice constants were determined, showing a reduction in Crystallite size of CAO from 45.98 nm to 37.55 nm after Fe3 + doping. Then, with the formation of CAFONZO Crystallite size 13.99 nm was obtained. FT-IR analysis revealed the chemical interactions between atoms in the spinel structures Nitrogen adsorption/desorption isotherms were used to determine the specific surface area of nanoparticles, pore volume, and pore size. Specific surface area of CAO, CAFO, and CAFONZO are 1.637, 1.745, and 9.903 (m2/g), respectively. SEM and TEM images provided insight into the morphology and size of the nanoparticles. According to TEM images, after Fe3 + doping, the size of particles decreased from 85 to 32 nm. UV-DRS was performed to determine the optical band gap energy of the photocatalysts. The calculated band gap values of pure CAO, CAFO, and NZO nanoparticles were 3.2 eV, 2.5 eV, and 2.7 eV, respectively. Mott-Schottky analysis indicated the type of semiconductors and the energy levels of the conduction and valence bands. Valence band (VB) values of CAFO and NZO are 2.86 eV and 2.03 eV, respectively. The photocatalytic activity of the nanoparticles was evaluated by degrading MB under visible light illumination. The adsorption studies were conducted by varying the dosage, pollutant concentration, and pH. The results showed that CAFONZO nanoparticles exhibited the highest photocatalytic efficiency, achieving 96 % degradation of MB within 120 min. The combined photocatalyst demonstrated improved efficiency compared to the individual components.