Heterogeneous photocatalytic degradation of anthraquinone dye Reactive Blue 19: optimization, comparison between processes and identification of intermediate products

Abstract

Treatment of textile wastewater using heterogeneous photocatalysis began in the the last decade and attracted the attention of researchers due to its versatile application. The variety of applications of TiO2 as a photocatalyst was due toits numerous positive properties, such as low operating temperature, biologically inert nature, low energy consumption, water insolubility, availability and photoactivity, low toxicity, high chemical stability, suitable flat band potential, narrow bandgap and the fact that it is environmentally benign. Heterogeneous UV-TiO2 photocatalysis is capable of removing organic pollutants from textile wastewater; this has been widely studied, with the technology also having been commercialized in many developing countries. Decolorization of anthraquinone dye Reactive Blue 19 (RB 19) by heterogeneous advanced oxidation processes TiO2/UV/H2O2, TiO2/UV/KBrO3 and TiO2/UV/(NH4)2S2O8 was studied under different conditions and in the presence of electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and ammonium persulphate ((NH4)2S2O8). Decolorization was very fast for all three processes, and complete dye decolorization was achieved in 10 min. The effect of various ions (Cl–, SO42– and HCO3–) on RB 19 decolorization was also studied. The optimal condition for the decolorization of the dye were determined to be: TiO2 concentration 1 g∙dm–3, electron acceptor concentration 30.0 mmol∙dm–3, dye concentration 50.0 mg∙dm–3, UV intensity 1 950 μW∙cm–2, at temperature 25 ± 0.5°C. In addition, experiments were performed and compared in three different matrices. In the surface water and dyebath effluent water, the removal efficiency for RB 19 was lower than that achieved in the deionized water because of the interference of complex constituents in the surface water and effluent. LC-MS analysis was carried out and the detected intermediates were compared with the previously published data for anthraquinone dyes.

Solar expedited photodegradation of orange-g using H2O2

“…Similar results were observed in case of Miljina D Radovic et al in case of decolourisation of Reactive Blue 19 dye degraded by UV/H 2 O 2 which also had its decrease in photodegradation which contains NaH 2 PO 4 as an additive in the concentration of 1 M [24]. …”

Synergistic Effect of the KBrO3 Electron Acceptor on the Photocatalytic Performance of the Nb-TiO2 Nanocomposite for Polluted Phenol Red Wastewater Treatment

“…KBr and KI were used at various concentrations and pH values on the photocatalytic degradation of dye W-7G using nanoscaled TiO 2 [17]. TiO by heterogeneous advanced oxidation processes under different conditions [18]. Although there has been some research work on the effect of acceptors such as KBrO 3 on metal/TiO 2 nanocomposites, no work has been reported elsewhere on the effect of acceptors on the new photocatalysts Nb/TiO 2 nanocomposites reported recently in our work.…”

Titanium Dioxide as the Most Used Photocatalyst for Water Purification: An Overview

“…In some cases, photocatalytic activity is completely suppressed without O 2 . Besides O 2 , other substances could be used as electron acceptors, such as H 2 O 2 , KBrO 3 , and (NH 4 ) 2 S 2 O 8 [199,[220][221][222][223]. H 2 O 2 has a significant role in this group of electron acceptors since it efficiently suppresses the recombination of e − −h + pairs through reduction with e − from the CB, which separates the charges (reaction ( 16)) and it represents the source of additional • OH (reactions ( 16) and ( 17)) [224]:…”

“…This increases the quantum yield of processes catalyzed with TiO 2 . Reactions that include these two radicals are the following (reactions ( 19)-( 22)) [220,[225][226][227]:…”