Biosynthesis of lead oxide nanoparticles using mulberry leaf extract for adsorptive removal of diazine black dye

The synthesis of metal oxide nanoparticles and their subsequent use in the adsorptive removal of emerging pollutants using commonly used physicochemical methods require harsh conditions, and hazardous chemicals are produced. It is the need of the hour to find certain biological methods that are eco-friendly, highly efficient, inexpensive, and easy to use with reduced usage of equipment and chemicals and no emission of toxic chemicals. In this regard, the present study involves the biosynthesis of lead oxide nanoparticles (PbO-NPs) using mulberry leaf extract for the adsorptive removal of diazine black dye. PbO-NPs were characterized by different analytical techniques, including FTIR, SEM, EDX, XRD, BET, TGA, zeta potential, and point of zero charge (pH) (PZC). Optimum adsorption (99.9%) of diazine black dye by PbO-NPs occurred at an initial concentration of 100 ppm diazine black, a contact time of 30 min, a temperature of 343 K, and 0.1 g of adsorbent at a pH value of 10. Various linear kinetic and adsorption isotherms were applied to determine the mechanisms of the adsorption process. Different adsorption isotherms, such as Freundlich, Temkin, Dubinin-Radushkevich (D-R), and Langmuir models, were applied in this study. The Elovich, intraparticle, pseudo-1st order, and pseudo-2nd order kinetic models were applied among the kinetic models. The best results were shown by all isotherms except pseudo-second-order kinetic modes (type II, type III, and type IV). In conclusion, the biosynthesized PbO-NPs had great potential for the adsorptive removal of diazine black dye, as evidenced by condition optimization, model application, and characterization.