Ozone decomposition on ZnO catalysts obtained from different precursors

Kinetic investigations for ozone conversion on three different series of zinc oxide catalysts, containing pure ZnO and doped with Mn or Cu one with dopant content less than 1 wt.% were carried out. The different samples were obtained from carbonate, nitrate and acetate precursors. The as prepared catalysts were characterized by AAS, XRD, IR, EPR and BET methods. The mean size of the crystallites determined by XRD data is in the range 27÷68 nm. The presence of Mn2+ and Cu2+ ions into the ZnO matrix was established by EPR. The ozone decomposition was investigated for 30÷75°C temperature range. The zinc carbonate precursor samples show highest activity, while the nitrate precursor ones show lowest activity toward reaction decomposition of ozone in the whole temperature range. At 75°C two of the catalyst, obtained from carbonate precursor - ZnO and CuZnO show 100% conversion

DISCOLORATION OF REACTIVE DYES IN WASTEWATERS BY OZONATION

Three different reactive dyes - Reactive Blue 19, Reactive Orange 16 and Reactive Red 180 were dissolved in water separately in concentration 0.04g/l as model pollutants for contaminated wastewaters from textile industry. Every wastewater sample was treated by ozone with concentration 2000 ppm for 30 minutes at ambient temperature and the effect of discoloration was traced after 5, 10, 20 and 30 minutes. The highest degree of discoloration was obtained for Reactive Blue 19 model water pollutant dye where 98% discoloration was reached after 5 minutes ozonation and 99% after 30 minutes treatment, while the lowest discoloration was observed for Reactive Orange 16 – 84% after 30 minutes treatment. The discoloration degree for the three sample solutions in the whole time interval was as follows: Reactive Blue 19 > Reactive Red 180 > Reactive Orange 16. In summary it can be concluded than application of ozone treatment for wastewaters, containing different reactive dyes is very effective and practically applicable