Adsorption of Uranium(VI) ions by nano Cu-doped ZrO2: A response surface methodology approach

The increasing concerns over environmental sustainability and the preservation of biodiversity highlight the urgent need for effective management of water resources, which are vital for human well-being. Uranium, which is used as an energy source in nuclear power plants, poses significant environmental hazards due to its biological toxicity and the radioactive waste generated from mining and milling processes. This study focuses on the development of a novel copper (Cu) doped nano zirconia (Cu-ZrO2) adsorbent synthesized via the ignition method for the efficient removal of uranium(VI) from contaminated water. The adsorbent was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, Xray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX) techniques. The adsorption process was further optimized using Response Surface Methodology (RSM) to evaluate key parameters including pH (3-8), temperature (20-60 degrees C), uranium (VI) concentration (25-125 mg/L), and adsorbent dosage (0.0025-0.04 g). A central composite design (CCD) indicated a second-order model with R2 and adjusted R2 values of 0.9823 and 0.9344, respectively. The adsorption studies demonstrated a maximum uranium(VI) adsorption capacity of 246.21 mg/g for Cu-ZrO2, which is significantly higher than that of pure ZrO2(24.12 mg/ g). Thermodynamic analyses revealed that the adsorption process is endothermic, with an increase in adsorption capacity at elevated temperatures. The adsorption mechanism was best described by the Freundlich isotherm, indicating a heterogeneous surface and multilayer adsorption. This research contributes to advancing uranium removal technology from water sources, providing an environmentally friendly and cost-effective solution to mitigate the risks associated with uranium contamination.