Degradation of azo dye Procion Red MX-5B by photocatalytic oxidation

• Published in: Chemosphere (Oxford) Vol. 46; no. 6; pp. 905 - 912
• Main Authors: So, C.M, Cheng, M.Y, Yu, J.C, Wong, P.K
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-02-2002; Elsevier
• Subjects: Applied sciences; Azo Compounds - chemistry; Catalysis; Coloring Agents - chemistry; Exact sciences and technology; hydrogen peroxide; Hydrogen Peroxide - chemistry; Hydrogen-Ion Concentration; Industrial wastewaters; Mineralization; Oxidants - chemistry; Oxidation-Reduction; PCO; Photochemistry; Pollution; Titanium - chemistry; Titanium dioxide; Waste Disposal, Fluid; Wastewaters; Water Purification - methods; Water treatment and pollution; UV; Mineralization; PCO; Titanium dioxide; Discoloration; Hydrogen peroxide; Organic dye; Photocatalysis; Operating conditions; Heterogeneous catalysis; Ultraviolet radiation; Industrial waste water; Azo dye; Physicochemical purification; Oxidation; Waste water purification; Titanium oxide; Photooxidation; Textile industry; Photochemical degradation
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(01)00153-9

The photocatalytic oxidation (PCO) of a monoazo dye Procion Red MX-5B under various physico-chemical conditions was investigated. Degradation of the dye by PCO was enhanced by augmentation in UV intensity, titanium dioxide and hydrogen peroxide concentrations but was inhibited by increase in initial dye concentration. The PCO process was affected by pH in a peculiar way. In the presence of 100 mg/l of TiO
2 and the absence of H
2O
2, the highest reaction rate was observed when the initial pH was 10. With 500 mg/l of TiO
2 and 10 mM of H
2O
2, the reaction was the fastest at initial pH of 3–5. The optimal conditions for the degradation of the dye, at an UV intensity of
17
mW/
cm
2
, were determined to be: TiO
2 concentration, 500 mg/l; initial H
2O
2 concentration, 10 mM; initial pH, 5.0. Monitoring of TOC loss showed that the dye was mineralized by 90% within 80 min under these conditions. Nevertheless, the persistence of a low level of TOC indicated that mineralization was not complete and dead-end product(s) which was (were) resistant to PCO might have accumulated.