Experimental design to optimize the synthesis of CdO cauliflower-like nanostructure and high performance in photodegradation of toxic azo dyes

In this study, the photodegradation of some water pollutants in the presence of CdO cauliflower-like nanostructure as a photocatalyst has been investigated. This architecture was synthesized using mechanochemical process followed by heating treatment. An experimental design was done to evaluate the synthesis conditions and determine the optimum reaction via the band gap energy optimization. This parameter, selected as a response for the design of experiments (DOE), was estimated by the diffuse reflectance spectroscopy (DRS). Four factors of the calcining temperature, milling duration, calcining duration and reactants molar ratio (M/L) were chosen to have a sequence of 9 samples to analyze. The optimized structure with the band gap energy of 2.22 eV and high surface area showed the highest removal efficiency for the applied pollutants. The results revealed that this product can be prone for degradation activity in a visible region. Minitab and Qualitek-4 statistical softwares were used for data analysis.

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► Statistically designed experiments were used to optimize CdO nanostructure.
► The optimal CdO cauliflower nanostructure was prepared by mechanochemical process.
► The optimized nanostructure was used to remove dye pollutants from aqueous solution.
► Congo red, Malachite green and Crystal violet were selected as model dyes.
► Photodegradation efficiency of 100% proved the high performance of this material.