Phytogenic Nickel Oxide Nanoparticles for Phosphate-Induced Eutrophication Control and Nutrient Recovery as an Eco-Friendly Fertilizer

Excessive phosphate discharge into aquatic environments has become a primary driver of eutrophication, leading to harmful algal blooms, oxygen depletion, and widespread ecological degradation. Addressing this environmental challenge, the present study explores a green and sustainable approach to phosphate mitigation through the synthesis and application of phytogenic nickel oxide (NiO) nanoparticles. NiO NPs were fabricated using bioactive phytochemicals derived from plant extracts, serving as natural reducing and stabilizing agents—eliminating the need for toxic reagents and high-energy processes. The nanoparticles were thoroughly characterized by FTIR and XRD, confirming their crystalline structure, high surface area, and nanoscale morphology. Batch adsorption studies revealed remarkable phosphate removal efficiency across a wide pH range, with optimal adsorption. The NiO NPs also exhibited excellent recyclability over multiple adsorption-desorption cycles with minimal loss in efficiency. The recovered phosphate was converted into a phosphate-rich fertilizer suitable for agricultural application. This demonstrates the feasibility of recycling recovered phosphate as a sustainable agricultural nutrient source. This study not only validates the potential of phytogenic NiO nanoparticles as effective adsorbents for phosphate removal but also contributes a green nanotechnology solution for combating eutrophication and restoring aquatic ecosystem health.