Statistical optimization modeling of organic dye photodegradation process using slag nanocomposite

The photocatalytic activity of three solvothermal prepared steel slag nanocomposites, SSNP-10, SSNP-20, and SSNP-30, was tested in this work for methylene blue (MB) dye degradation. Using SSNP for the first time, the photocatalytic degradation of MB dye was optimized using Box-Behnken design (BBD) in a response surface approach. The influence of essential operating parameters was experimentally examined, modeled, and optimized. The analysis of variance (ANOVA) results revealed that the suggested quadratic models significantly agreed with the experimental investigation, with p-values less than 0.0001 and an R-2 value of 0.9914. Accordingly, the optimized conditions were 32.83 mg catalyst dose, 11.42 pH, 41.34 min irradiation times, and 10.63 mg/L MB dye concentration. The optimized degradation efficiency of the MB dye was 89.43% under these conditions. The result was experimentally validated with the optimal operating parameters for SSNP-10, SSNP-20, and SSNP-30, and the photodegradation efficiencies were 90.07%, 88.94%, and 87.28%, respectively. A pseudo-first-order reaction kinetics of 0.0293, 0.0291, and 0.0267 was achieved for SSNP-10, SSNP-20, and SSNP-30 with a regression coefficient of 0.9514, 0.9312, and 0.9042, respectively. According to Pareto analysis, the operational factors that had the greatest effect on dye degradation efficiency were catalyst dosage (F-value 585.32) > MB concentration (F-value 423.89) > irradiation period (F-value 368.01) > pH (F-value 362.34). The results showed that the SSNP catalyst was the key parameter for the generation of hydroxyl radicals responsible for the photodegradation of MB dye and may be useful for other contaminants' degradation. [GRAPHICS] .