Catalytic wet oxidation degradation of malachite green with Cu-coated sediment as catalyst: parameter optimization using response surface methodology

This research focuses on developing a supported catalyst by impregnating Moroccan Sebou River sediment with copper (Cu) through a wet impregnation method. Different catalyst loading levels (5, 10, and 15 wt.%) were employed. These catalysts were tested in catalytic wet peroxide oxidation (CWPO) to degrade malachite green (MG) dye using hydrogen peroxide (H 2 O 2 ) as oxidant. Moreover, the response surface methodology based on the Box–Behnken design (BBD) was used to investigate and optimize the operating parameters affecting the decolorization process, such as temperature, catalytic dose, metal loading, and hydrogen peroxide amount, which were systematically investigated. An MG degradation efficiency of 99.84% was achieved after a reaction time of 60 min under the following conditions: [MG] = 100 mg/L, dose = 0.2 g/L (catalyst 15 wt.%), [H 2 O 2 ] = 1 mM, and T = 40 °C. The mineralization efficiency reached 74% in terms of chemical oxygen demand (COD) removal. As a result, the solution treated under these optimized conditions showed low toxicity based on the corn grain germination test. Reusability tests on the 15 wt.% catalyst showed a decrease in degradation efficiency by 8.45%, indicating high catalytic stability. Graphical abstract