This study was carried out to ascertain the effect of photochemical and non-photochemical AOPs (O3 alone, O3/H2O2, UV alone, UV/H2O2 and Fenton’s process) on the decolorization of sulphatoethylesulphone reactive group azo dye (Remazol Black B). All experiments were performed on a laboratory scale set-up and room temperature. Initial results showed that decolorization by UV alone were not effective because dye was photolytically stable and resistant to direct UV irradiation. However, the addition of appropriate amount of H2O2 improved color removal efficacy and the dye degradation. The research results showed that color removal efficiencies by O3/H2O2, UV/H2O2 of synthetic dye solution containing 100 mg/l concentration were found efficient. Ozone assisted hydrogen peroxide (O3/H2O2) treatment yielded about 98% decolorization at pH 9 and 25 minutes ozone exposure time. At 15 minutes of UV exposure with 4.4 mM H2O2 dose, 99% color removal efficiency was achieved. It is evident from results that the addition of H2O2 in the O3 and with UV irradiation accelerated the decomposition and degradation of synthetic dye solution through an increased rate of hydroxyl radical (HO•) generation which has high oxidation potential. Fenton’s process (H2O2/Fe+2 reagent) showing remarkable results (99.9%) in terms of color removal in just 5 minutes at pH 3 while keeping optimal iron (Fe2+) dose of 0.25 mM and hydrogen peroxide (H2O2, 30% w/w ) concentration 2.2 mM in effluent. Ultraviolet (UV) assisted with H2O2 also proved promising technique after Fenton’s process. There was about 99% color removal in 15 minutes UV exposure time at pH 5 value. Findings of the study clearly revealed that synthetic dye (Remazol Black B) effluent was degraded successfully by all examined advanced oxidation processes (AOPs) except UV alone irradiation at feasible treatment time, initial pH and adequate H2O2 dose value.
Nabeela Firdous, Irfan Ahmed Shaikh and Rukhsana Shahid
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