APCATA 492-2015-169–

Tailoring the metal introduction sequence onto mesostructured silicananoparticles framework: Effect on physicochemical properties andphotoactivity

Cu with variable weight loading (1–5 wt%) was introduced to 5 wt% Zn mixed mesostructuredsilica nanoparticles (MSN) via an electrochemical method to synthesize CuO–ZnO/MSN (C-ZM) cat-alysts. The physicochemical properties of the catalysts were characterized by XRD, FTIR, XPS, N2adsorption–desorption, ESR, and cyclic voltammetry. 3 wt% Cu and 5 wt% Zn were also introduced alter-nately to MSN (3C-ZM and Z-3CM) to study the metal introduction sequence effect on the propertiesand catalytic activity. The characterization data showed that an altered arrangement of the silica net-work was observed with a different structure, particularly in the numbers of Si O Si, Si O Zn, andSi O Cu bonds as well as oxygen vacancies. The catalytic activity regarding the photodecolorization ofmethyl orange (MO) was in the following order: 3C-ZM > 5C-ZM > Z-3CM > 1C-ZM. The higher numbers ofSi O Zn, oxygen vacancies, and the higher pore volume of the 3C-ZM catalyst seemeed to be the mainfactors behind its higher photoactivity compared to the other catalysts. Further optimization by responsesurface methodology (RSM) with a central composite design (CCD) model was performed for the decol-orization of MO. RSM demonstrated that the experimental value (99.89%) was reasonably close to thepredicted value (99.99%) with only 0.1% error for MO decolorization at pH 3.5 using 1.6 g L−1catalyst with4 wt% Cu loading.