green chemistry approach for the study of methylene blue degradation in aqueous medium by cao photocatalysts under led and halogen irradiation

This work presents a green chemistry approach to investigate the photocatalytic degradation of methylene blue in aqueous medium using calcium oxide (cao) as a photocatalyst under led and halogen irradiation. the study focuses on how calcination temperature and light source influence the photocatalytic activity of cao. structural characterization (ftir, sem, and edx) confirmed that increasing the calcination temperature from 1,000 °c to 1,100 °c enhances the crystallinity and homogeneity of cao particles. photocatalytic experiments revealed that, in the absence of light, the degradation rate remains low (< 3%), confirming that photocatalysis is the main degradation pathway. under halogen lighting at 1,000 °c, 60% of methylene blue degraded within 40 minutes, while led irradiation achieved 30%. at 1,100 °c, performance improved markedly: halogen light yielded 80% degradation after 60 minutes, compared to 50% under led. the ph of the solution significantly affected efficiency; in basic medium (ph 9), led irradiation led to 90% degradation at 1,100 °c, surpassing halogen (50%). in acidic medium (ph 2), efficiency remained below 25% under all conditions. complete (100%) degradation was achieved at a catalyst mass of 15 mg under halogen light at 1,100 °c. these findings highlight the importance of optimizing physicochemical parameters to improve cao-based photocatalysis and emphasize the potential of green chemistry principles for sustainable pollutant degradation.