Photodegradation, kinetics and non-linear error functions of methylene blue dye using SrZrO₃ perovskite photocatalyst

The degradation of methylene blue dye-contaminated wastewater via photocatalysis is an efficient approach towards environmental remediation. The SrZrO₃ perovskite photocatalyst was synthesized using the modified Pechini sol-gel method, and characterized using XRD, FESEM, FTIR, and UV-visible spectrophotometer. Crystallite size obtained by the Scherrer and Williamson-Hall methods were 45.56 and 44.50 nm, respectively. The sample exhibited an orthorhombic crystal structure. The optical bandgap was estimated to be 5.31 eV. Kinetic study for the degradation of methylene blue dye using SrZrO₃ in the presence of H₂O₂ showed complete decontamination of the methylene blue dye in the time interval of 90-120 min under visible light irradiation. The degradation efficiency was above 80.1 % under illumination and less than 40.1 % in dark. Kinetic studies were performed by varying the dose of photocatalyst and initial concentration of methylene blue. It was observed that higher dose of the photocatalyst and lower concentration of the contaminant produced higher rate of degradation. The solution pH 3 and catalysts dosage of 200 mg yielded the highest rate of degradation. The experimental data fitted best into the Psuedosecond order kinetic model with the highest R² value, indicating a strong linear relationship. The experimental data was subjected into nonlinear error functions, where the Psuedo-second order kinetic model demonstrated lower values of error functions. The results suggest that the prepared SrZrO₃ photocatalyst coupled H₂O₂ is a promising photocatalyst for the decontamination of methylene blue dye under visible light irradiation.