Study on Degradation of Crystal Violet by UV/Fenton/Heteropolyacid System

Abstract

The degradation of an azo dye crystal violet by UV/Fenton oxidation process in the presence of heteropolyacid solution has been investigated. The degradation rate is strongly dependent on the pH, initial concentrations of the dye, Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> , H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and phosphotungstic acid. The effect of these parameters has been studied and the optimal reacting conditions were experimentally determined. It was found to be initial pH 2.7, [H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ] =71 mM, [Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> ] = 0.5 mM, [dye] <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> = 20 mg/L, phosphotungstic acid concentration is 24 mg/L. Under optimal conditions, 95% degradation efficiency of dye in the presence of heteropolyacid solution was achieved after 60 min of reaction. The experimental results showed that the UV/Fenton oxidation process was an effective process for the degradation of crystal violet at low H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> concentrations. Meanwhile, this research also proved that heteropolyacid could improve the photocatalytic efficiency in the UV/Fenton reaction as an efficient activator.