A. Shajahan and M. Pavithra
Abstract
The present study investigates the photocatalytic and adsorption efficiency of activated Albizia lebbeck as a sustainable and eco-friendly material for the removal of Rhodamine B dye from aqueous solutions under solar irradiation. The photocatalytic degradation process was monitored using UVâVisible spectroscopy, which showed a gradual decrease in absorbance at 554 nm, confirming effective dye degradation. Maximum removal efficiency of 90.53% was achieved after 150 minutes of sunlight exposure. The influence of operational parameters such as initial dye concentration, catalyst dosage, and pH was systematically evaluated. Optimum conditions for maximum decolourization were found at 10 mg/l dye concentration, 20 mg/l catalyst dosage, and neutral pH (pH 7). Adsorption isotherm studies indicated that the process follows both Langmuir and Freundlich models, suggesting monolayer adsorption along with heterogeneous surface interactions. The calculated separation factor (RL = 0.656) confirmed favorable adsorption. Kinetic studies revealed that the adsorption process follows pseudo-first-order kinetics, indicating that physical adsorption predominates. The characterization studies demonstrate that activated Albizia lebbeck possesses abundant functional groups (FTIR) and highly porous surface morphology (SEM). Overall, the results demonstrate that activated Albizia lebbeck is an effective, low-cost, and environmentally friendly adsorbent photocatalyst with significant potential for wastewater treatment applications using solar energy.