Photo-degradation of the methyl blue: Optimization through response surface methodology using rotatable center composite design

Abstract

Advanced oxidation processes (AOPs) generate in situ active hydroxyl radicals, allowing for the destruction of polluting agents through mineralization. The suitable experimental design allows adjustment of factor levels to obtain an optimal response in experimental analysis. Rotatable Center Composite design and multivariate analysis are used for the optimization of the removal of methyl blue from aqueous solution, using UV (254 nm) radiation source and hydrogen peroxide as an oxidant. A factorial design (2ⁿ) with repeated central and axial points was used to obtain the best experimental condition to efficiently remove the dye from aqueous solution. Initial concentration, 50- 150 ppm and hydrogen peroxide 0.05- 5.95 % was used as experimental variables and obtained 96.5% dye removal, with a rate constant of 0.33 min^-1. Dye degradation followed the first order kinetics and Dissolved Oxygen (DO) and pH of the solution was found strongly correlated with degradation.