Biogenic synthesis of ZnO nanoparticles using Aspergillus flavus for sustainable removal of strontium ions from contaminated water based on bioremediation technology

Abstract Addressing the environmental risks associated with inorganic pollutants, such as heavy metals and radionuclides, requires a shift toward sustainable remediation strategies. The primary objective of this study is to investigate biosynthesized zinc oxide nanoparticles (ZnO NPs) using Aspergillus flavus for environmental bioremediation. Characterization verified the successful synthesis of crystalline (30–60 nm). Batch sorption experiments demonstrated selectivity for strontium, achieving a maximum equilibrium uptake (q e ) of ~ 30.5 mg g −1 under optimized conditions (pH of 8, 5 h, 0.05 g adsorbent, 25 mg/L initial concentration, 25 ± 2 °C). Isotherm and kinetic data followed the Langmuir model and pseudo-second-order kinetics, respectively, while thermodynamic analysis indicated an endothermic process. Furthermore, ZnO NPs (5–100 mg/mL) exhibited dose-dependent antibacterial, notably against K. pneumoniae and S. aureus , though they showed no effect on the tested fungal strains. Better sorption affinity of Sr rather than Cs is reported. These findings establish biogenic ZnO NPs as effective material for targeted wastewater treatment and promising candidates for antibacterial applications towards eco-friendly method based on bioremediation technology.