Nickel-doped ZrO2 nanoparticles for dual applications: Cadmium removal and antibacterial activity

The continuous discharge of cadmium (Cd), a bioaccumulative, non-biodegradable teratogenic and carcinogenic heavy metal poses significant environmental and public health concerns. Its efficient removal from water is crucial to comply with the 3 ppb guideline established by the World Health Organization (WHO). However, conventional treatment techniques such as adsorption and chemical precipitation often suffer from high operational costs, limited efficiency, and the generation of secondary pollutants. The novelty of this work is mainly to synthesize the Ni-doped ZrO₂ nanoparticles using the sol–gel combustion method and investigating their effectiveness when compared to traditional treatment methods for Cd²⁺ adsorption and antimicrobial activity in contaminated aqueous systems. X-ray diffraction (XRD) study indicates the successful incorporation of Ni into ZrO 2 matrix without its changes of crystal structure (tetragonal phase). The average crystallite size of Ni-doped ZrO₂ was slightly smaller (24.0 nm) than that of pure ZrO₂ (26.1 nm). Optical bandgap of pure ZrO 2 was 3.22 eV, however it was 3.10 eV for Ni doped ZrO 2 nanoparticles was conformed through UV-Vis diffuse reflectance spectroscopy. An increased specific surface area was observed for Ni doped ZrO 2 nanoparticles (126 m²/g), when compared to that of pure ZrO 2 nanoparticles (103 m²/g) through BET analysis. The optimized Ni-doped ZrO₂ nanoparticles exhibited a Cd (II) adsorption capacity of 93 mg g⁻¹ under the optimal experimental conditions, including an adsorbent dosage of 40 mg, an initial Cd (II) concentration of 6 ppm, a contact time of 50 min, and a solution pH of 5. Additionally, antimicrobial assays revealed inhibition zone diameters of 10 mm and 11 mm against E. coli and S. aureus , respectively, highlighting the dual functionality of Ni-doped ZrO₂ in water purification applications.