Studies on the equilibrium, thermodynamics, and kinetics of the biosorption of copper (II) and lead (II) onto Indian willow (Salix tetrasperma) leaves

Potentially toxic metals in water threaten humans, animals, and the environment. The potential of Indian willow (Salix tetrasperma) leaves to biosorb copper and lead from water was examined. Utilising scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and Fourier transform infrared spectroscopy (FTIR) spectrum analysis, the properties of Salix tetrasperma biomass (STB) was investigated. The maximum removal percentage (92.8% for copper and 89.9% for lead) was achieved at pH 5.0, a biosorbent dosage of 3.0 g/L at 25 degrees C, and a 10 mg/L initial concentration of copper and lead. The determination of the point zero charge (pHzpc = 5.0) indicated the prevalence of a negative charge on the surface of the biosorbents. The kinetic equation utilised in the pseudo-second-order model effectively. Langmuir isotherm better described experimented data than the Freundlich model. The Dubinin-Radushkevich isotherm provided a good fit for the study's equilibrium data. STB recorded an adsorption capacity, Qmax, of 43.99 mg/g for copper (II) and 39.66 mg/g for lead (II) ions at an optimum pH of 5. Thermodynamically, the biosorption of both ions on STB was spontaneous, endothermic, and feasible. The selected modified STB was found to be suitable for adsorbing copper (II) and lead (II) metal ions.