The effect of operational parameters on UV/H2O2 decolourisation of Acid Blue 74

Decolorization Kinetics of Acid Azo Dye and Basic Thiazine Dye in Aqueous Solution by UV/H2O2 and UV/Fenton: Effects of Operational Parameters

“…The impact of solution pH on the oxidation of target compounds and hydroxyl radical formation in the UV/H 2 O 2 advanced oxidation process has been investigated in many studies [13,14]. In this field, the reactivity of hydrogen peroxide and the reaction rates of target compounds were found to depend on the solution pH.…”

Effects of system parameters and inorganic salts on the photodecolourisation of textile dye Reactive Blue 19 by UV/H₂O₂ process

“…An increase in dye concentration induces a rise in internal optical density and the solution becomes more and more impermeable to UV irradiation. In this way, H 2 O 2 can only be irradiated by a small portion of UV light to form fewer free radicals and colour removal decreases (Elmorsi et al, 2010;Ghodbane et al, 2010;Muruganandham et al, 2004;Aleboyeh et al, 2005;Behnajady et al, 2004;Galindo et al, 1998).…”

“…Colonna et al (1999) reported that homogenous advanced oxidation processes employing hydrogen peroxide with UV light lead to complete decolourisation and mineralisation of sulphonated azo and anthraquinone dyes. This process is based on the generation of hydroxyl radicals (•OH), and a strong oxidising agent (E 0 = 2.8 V), which degrade a broad range of organic pollutants quickly and non-selectively (Muruganandham et al, 2004;Aleboyeh et al, 2005;Daneshvar et al, 2005). Reaction of hydroxyl radicals generated in the presence of an organic substrate may occur via one of three general pathways: (i) hydrogen abstraction; (ii) electrophilic addition and (iii) electron transfer (Daneshvar et al, 2005).…”

“…hydroxyl radical is a non-selective and very powerful oxidising agent and can initiate the decolourisation reactions by reacting with the dye molecules (Zollinger, 2003;Muruganandham et al, 2004;He et al, 2008;Aleboyeh et al, 2005;Daneshvar et al, 2005;Aleboyeh et al, 2003;Daneshvar et al, 2003).…”

“…For an acidic pH, with acidification of the solution by HCl (dye solution with initial pH 2, 3, 4 and 5), the amounts of conjugated base Cl -ions increase. The anion Cl -can react with •OH leading to the formation of inorganic radical ions ClOH• -(Reaction (7)) (Aleboyeh et al, 2005;Jaysona et al, 1973). These inorganic radical anions show a lower reactivity than •OH, so that they do not play a role in the decolourisation of RB 19.…”