Innovative ZnO-W₁₈O₄₉ nanocomposites and ZnWO₄ nanostructures for water treatment

Nanomaterials including zinc oxide (ZnO) and non-stoichiometric (W₁₈O₄₉) tungsten oxide can be applied to solve the challenge related to optical properties of nanomaterials like global problems related to water treatment. Therefore, successful syntheses of zinc oxide-tungsten oxide nanocomposites and ZnWO₄ nanostructures are reported by hydrothermal method and using different masses of green synthesized ZnO nanoparticles (NPs). The nanostructures are pure and only zinc, tungsten, and oxygen elements are observed in the synthesized samples. Alterations of green synthesized ZnO NPs mass used in the nanocomposite synthesis process influence the nanocomposites' structural, morphological, and optical properties. Different morphologies including nanorods, nanofibers, cabbage-like structures, short nanorods, and nanoflakes are formed using different masses of the used ZnO NPs. The photocatalytic activities of the nanocomposites are evaluated by removing methylene blue (MB- 10 ppm) under UV irradiation in the neutral (pH = 7) and acidic (pH = 5) solutions. Interestingly, 10 mg of ZW0.05 nanocomposite demonstrates the excellent deterioration of MB with efficiencies of 99% and 91% within 170 min in the neutral and acidic solutions, respectively. Furthermore, the quantity of catalyst was reduced to 5 mg, demonstrating the capacity to degrade 87% (94%) of MB at pH = 7 (pH = 5). Therefore, one of the synthesized nanocomposites can be an excellent candidate for water treatment even in acidic condition.