Removal of the hazardous dye—Tartrazine by photodegradation on titanium dioxide surface

The removal of the dye—tartrazine by photodegradation has been investigated using titanium dioxide surface as photocatalyst under UV light. The process was carried out at different pH, catalyst dose, dye concentration and effects of the electron acceptor H2O2. It was found that under the influence of TiO2 as catalyst, the colored solution of the dye became colorless and the process followed a pseudo first order kinetics. The optimum conditions for the degradation of dye were 6 × 10− 5 M dye concentration, pH of 11, and 0.18 mg/L of catalyst dose. In order to evaluate the effect of electron acceptor, the effect of H2O2 on the degradation process was also monitored and it was found that the hydroxyl radical formation and retardation of electron–hole recombination took place simultaneously. The adsorption studies of tartrazine at various dose of TiO2 followed the Langmuir isotherm trend. In order to determine the quality of waste water, Chemical Oxygen Demand (COD) measurements were carried out both before and after the treatment and a significant decrease in the values was observed, implying good potential of this technique to remove tartrazine dye from aqueous solutions.

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► Degradation efficiency increases with increase in catalyst concentration.
► Adsorption of tartrazine on TiO2 followed the Langmuir isotherm.
► The photocatalytic kinetics follows first order.