Biogenic Bismuth Nanoparticles from <i>Hippeastrum puniceum (lam). </i> voss for Enhanced Removal of Methylene Blue from Wastewater

Introduction: Industrial wastewater containing synthetic dyes such as methylene blue (MB) is a major environmental hazard due to its toxicity, stability, and resistance to biodegradation. Conventional treatment methods often face limitations in cost, efficiency, or by-product formation. In this work, an eco-friendly route was explored by employing Hippeastrum puniceum (Lam.) Voss extract to synthesize bismuth nanoparticles (Bi NPs) and assess their potential for dye removal. Methods: Leaves of H. puniceum were processed to obtain a phytochemical-rich extract, which served as a natural reducing and stabilizing agent for the conversion of bismuth nitrate into Bi NPs. The synthesis was optimized by adjusting precursor concentration, plant extract ratio, pH, temperature, and reaction time. The nanoparticles were purified and characterized by UV–Vis, FTIR, XRD, SEM, EDS, DLS, and zeta potential analysis. Batch adsorption studies were carried out to evaluate MB removal efficiency, and adsorption isotherms were applied to understand the mechanism. Results: The Bi NPs formed were spherical, moderately stable (−17.2 mV), and exhibited sizes in the 16–18 nm range. They achieved 84% removal of MB under optimized conditions (10 mg dose, 40 ppm MB, pH 7). The adsorption fitted well with the Langmuir isotherm, confirming monolayer dye uptake. Discussion: The plant-mediated synthesis proved simple, non-toxic, and effective, while the nanoparticles displayed higher removal efficiency compared to several reported adsorbents. Electrostatic attraction, hydrogen bonding, and π–π interactions collectively enhanced MB adsorption. However, long-term stability and recyclability remain to be tested. Conclusion: Biogenic Bi NPs synthesized from H. puniceum extract present a sustainable, lowcost material for dye removal. With further validation on reusability and scale-up, they hold strong potential for practical wastewater treatment applications.