Solar expedited photodegradation of orange-g using H2O2

Abstract

Decolourisation and degradation of azo dye Orange G was carried out by using the solarassisted photodegradation process using H2O2 and the effect of various parameters on decolourisation and degradation were analysed. Dye solutions of concentration 100 mg/L treated with 30% H2O2 were taken in 250 ml conical flasks and they were exposed to sunlight in the lux intensity range of 60,000 to 90,000 lux to study its decolourisation and degradation. Effect of various parameters on decolourisation and degradation of dye like the effect of initial pH, the effect of initial H2O2concentration, the effect of initial dye concentration, the effect of additives like chloride and dihydrogen phosphate of concentration 1 M, the effect of solar light intensity, the effect of temperature were studied as kinetic studies. Optimum pH was found to be 11 and optimum H2O2 concentration was found to be 250 mM to achieve 100 % decolourisation of the dye within the shortest time duration of 1.5 hours. Kinetic studies done on the effect of pH and the effect of H2O2 concentration also provided evidence for that. Effect of chloride ion has lead to enhancement in the rate of decolourisation whereas addition of dihydrogen phosphate ion inhibits the rate of decolourisation. An increase in solar light intensity has lead to increase in the rate of decolourisation. An increase in temperature has lead to increase in the rate of decolourisation. UV spectrum was taken for the dye and degraded dye to study the extent of degradation of the dye. COD and TOC removal were also studied to know about the mineralisation of the dye.