Kinetics of decolorization of an azo dye in UV alone and UV/H"2O"2 processes [An article from: Journal of Hazardous Materials]

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Description:
The decolorization of C.I. Acid Red 27 (AR27), a monoazo anionic dye, was studied in the ultraviolet radiation (UV) alone and UV plus hydrogen peroxide (UV/H"2O"2) processes. The experimental results indicated that the kinetics of both oxidation processes fit well by pseudo-first order kinetics. The reaction rate was sensitive to the operational parameters and increased with increasing H"2O"2 concentration and light intensity. The reaction orders of H"2O"2 concentration and light intensity in both processes were obtained with linear regression method. A regression model was developed for pseudo-first order rate constant (k"a"p","U"V"/"H"""2"O"""2) as a function of the H"2O"2 concentration and UV light intensity.k"a"p","U"V"/"H"""2"O"""2=(2x10^-^4I"0^0^.^7^5+k"3I"0^1^.^3^8[H"2O"2]"0^n)@f"A"R"2"7 As a result of two opposing effects of H"2O"2 concentration at low and high concentrations, n has a value of 0.49 and -0.39 and k"3 has a value of 3x10^-^4 and 0.1 for the regions of 0mgl^-^1