High-performance of Cu@eggshells for toxic dyes catalytic wet peroxide oxidation: Kinetics, design of experiments, regeneration, and cost analysis

Abstract

Catalytic reactivity performance is a significant challenge for catalytic wet peroxide oxidation (CWPO) technologies. Copper-impregnated eggshells (x%Cu@ES) were tested as a potential new low-cost catalyst to improve the CWPO process for the toxic dyes Congo Red (CR) and Crystal Violet (CV). The structure, morphology, and chemical composition of the x%Cu@ES catalyst were analyzed using FTIR, XRD, and SEM-EDX. Oxidative degradation of both dyes is enhanced by the presence of x%Cu@ES, which generates hydroxyl radicals in the reaction medium after contact with hydrogen peroxide. Decolorization rates according to the Box Behnken design are in the order of 99.88 % and 99.99 % for CR and CV respectively under the optimum conditions of 1 % copper content, 0.074 M H2O2 concentration, 60 mg L−1 dye concentration, and 2 g L−1 catalyst dose. After several regeneration cycles, the catalytic system's low metal release and constant catalytic activity proved the durability, stability, and viability of the 1%Cu@ES catalyst for dye degradation in CWPO. In addition to being environmentally friendly, the 1%Cu@ES catalyst material is highly economical for industrial application, costing around 0.061$ L−1 for the oxidation process in water.

Keywords

• Box behnken design
• Catalytic wet peroxide oxidation
• Eggshells
• Low-cost
• Regeneration