Monitoring of decolorization kinetics of Reactive Brilliant Blue X-BR by online spectrophotometric method in Fenton oxidation process

Online spectrophotometry method is employed to monitor simulated Reactive Brilliant Blue X-BR (RBB X-BR) in aqueous solution in Fenton oxidation process. The effects of initial dosage of FeSO₄ and H₂O₂, pH value, initial concentration of dye and temperature have been studied. The results show that online spectrophotometric method is a quick, feasible and convenient technique to monitor color removal of RBB X-BR in Fenton process. The optimal dosage of H₂O₂ and pH is 3.529 mM and 3, respectively. The optimal dosage of Fe²⁺ for color removal is 0.1618 mM. The concentration of initial FeSO₄ against the reaction rate constant (k_ap) for decolorizing is linear correlation as: k_ap = 0.1354[Fe²⁺]_o (R² > 0.99). The apparent activation energies of reaction is 25.21 kJ mol^-1 (R² > 0.99). The intrinsic reaction rate constant of {radical dot}OH with RBB X-BR in aqueous solution is 7.396 × 10¹⁰ M^-1 s^-1. The molecule structure of RBB X-BR is decomposed and not mineralized by Fenton's reagent. The main intermediate products are 1,2-diacetylenzene and 2,5-diritrobenzoic acid. The probable mechanism of the decoloration of RBB X-BR is also discussed.