Advancing sustainable photocatalysis: Methylene blue-loaded SBA-15 for efficient pollutant degradation under visible LED light

In this study, SBA-15 loaded with methylene blue (SBA-15-MB) was successfully prepared by simple adsorption of methylene blue onto the mesoporous SBA-15 material. XRD, SEM, FTIR, BET, DRS, and TGA analyses thoroughly characterized the photocatalyst. The photocatalytic performance of SBA-15-MB was evaluated for methyl orange (MO) degradation under visible LED light irradiation. Optimization studies were conducted to investigate the effects of catalyst dosage, initial MO concentration, and solution pH. The experimental results demonstrate that SBA-15-MB exhibits significantly higher photocatalytic activity than bare SBA-15 under visible light. Under optimal conditions (50 ppm MO, pH 5.5, and 30 W LED lamp), a degradation efficiency of 87 % was achieved within 180 min. The degradation kinetics followed a pseudo-first-order model with a reaction rate constant of 0.012 min⁻¹. Moreover, SBA-15-MB showed good photocatalytic performance toward the degradation of various pollutants, including dyes and antibiotics. The enhanced photocatalytic activity is attributed to the visible light excitation of methylene blue, followed by electron transfer from methylene blue to SBA-15 and radical generation at the catalyst surface. Significantly, SBA-15-MB can be regenerated by re-adsorption of fresh methylene blue, highlighting its potential as an efficient and recyclable photocatalyst for water purification under low-power visible light irradiation.