Studies on degradation of dyes present in the industrial effluents

Abstract

Brilliant Golden yellow, BGY, a textile dye, has been chosen for studying its degradation characteristics. Two methods of degradation have been tried. These methods are Fenton and mediated photodegradation. Two semiconducting oxides have been chosen as mediators. These are TiO, (rutile) and ZnO. BGY solution shows absorption peak at A",415:t 2 nm with E"'7.81x 103 Lmor'cm" at 29°C. The concentrations ofBGY was about 5.10xl0"M to 3.00 x 10,4M, the solution initial pH varied beltween 2.50 to 6.20. The concentration of H,O, was between 8.00 x 1O.4Mto 5.00 x IO'3M, the concentration of Fe (III) 2.00 x 10"M to 1.00 x I0.4M. The amount ofTiO, per 50 ml solution was 1.00 x 10.3 to 4.50 X 10'3g and the amount of ZnO per 50 m!. was 2.50 x 10'3 to 10.00 X 10,3g. The Fenton degradation of the BGY was complete within 10 minutes and so long '---- H,O, was in sufficiently large amount. The other parameters did not affect the % degradation of the dye, which was about 93% even in the presence 410 nm light. In the oxide mediated photodegradation 100% degradation of the BGY could be achieved by using 320 nm light. ZnO mediated degradation appeared to be faster. TiO, mediated degradation appeared to be dependent on the amount ofTiO" other parameters hardly affected the photodegradation process. Langmuir-Hinshelwood kinetic model has been applied to the mediated degradation. It gives some idea why ZnO is a better mediator for photodegradation ofBGY.