Central composite design (CCD) optimized synthesis of Fe3O4@SiO2@AgCl/Ag/Ag2S as a novel magnetic nano-photocatalyst for catalytic degradation of organic pollutants

In this study, we formulated and synthesized an efficient visible light-active magnetic nano-photocatalyst, Fe3O4@SiO2@AgCl/Ag/Ag2S, to decompose methyl orange (MO) as a model organic pollutant. XRD, SEM, TEM, EDS, DRS, and VSM analyses were used to characterize the developed magnetic nano-photocatalyst. Moreover, central composite design (CCD) modeling, which is based on response surface methodology (RSM) modeling, is utilized to optimize the synthetic and operating conditions to maximize the photocataytic performance. The CCD-optimized values for molar ratio of AgCl to Fe3O4, molar ratio of Ag2S to Fe3O4, and the photocatalyst dosage are found to be 0.8, 0.27, and 1.27 g/L, respectively. The developed Fe3O4@SiO2@AgCl/Ag/Ag-2 S nano-photocatalyst shows a superior photocatalytic activity in decomposition of MO, degrading around 90% and 99% of MO in 30 min and one hour, respectively, under visible light illumination, at which the predicted values are in a good agreement with the experimental values (R-2 = 0.971 and Adj-R-2 = 0.945). Meanwhile, the morphological, physicochemical, and magnetic properties of the developed nano-photocatalyst are largely retained over ten successive cycles of photocatalytic reactions, and no significant decline in the photocatalytic activity is observed.