Central composite design optimization of Bismarck Dye oxidation from textile effluent with Fenton's reagent

Coloured wastewater is discharged in a huge amount from textile industry as a result of using synthetic dyes that causes threat water pollution. A simple sol–gel technique was used to synthesis haematite nanocrystals as a source of photo-Fenton's reagent. The current work is dealing with the mineralization of Bismarck Brown dye (BBD) using such reagent, and the process parameters were optimized using response surface methodology. Central composite design of the two most important variables of the Fenton's reagent process (Fe³⁺ and H₂O₂ doses) was employed for the experimental design, and BBD removal was maximized. The suggested model investigated that the dye removal increases with the increasing of both reagents up to a certain limit then decreases afterwards. The reduction percentages of colour and chemical oxygen demand under the optimum operating parameters (37.21 mg/L of the haematite nanocrystal and 412.31 mg/L of H₂O₂) are found to be 76.5% and 73%, respectively. Analysis of variance and the high regression coefficient (98%) confirm a good estimation of the experimental values by polynomial regression model. Therefore, the exploration of using haematite nanocrystals as a Fenton's reagent source for treating textile effluents is recommended from this study.