Effect of chloride and sulfate ions on the advanced photo Fenton and modified photo Fenton degradation process of Alizarin Red S

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2013-08, Vol.374-375, p.125-131
• Main Authors: Devi, L. Gomathi, Munikrishnappa, C., Nagaraj, B., Rajashekhar, K. Eraiah
• Format: Article
• Language: English
• Subjects: Advance Fenton process; Alizarin Red S; Combined ionic effect; Modified Fenton process; Zero valent metallic iron powder
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2013.03.023

The degradation of Alizarin Red S was carried out by heterogeneous advanced photo Fenton processes of the type Fe0/H2O2/UV and heterogeneous modified photo Fenton process of the type Fe0/ammonium persulfate/UV and the influence of inorganic anions such as chloride (Cl−) and sulfate (SO42−) on these processes were investigated. Degradation mechanism involves the cleavage of a quinone group to form catechol. •Influence of Cl− and SO42− ions in the various Fenton process is studied.•Many of the industrial effluents contain these ions along with the pollutant.•Ammonium persulfate is used as the oxidant in photo Fenton process.•Sustainability of the photoreaction depends on the reactive free radicals formed.•A probable degradation mechanism of Alizarin Red S is proposed. The degradation of Alizarin Red S (ARS) was carried out by heterogeneous advanced photo Fenton processes (HAPFP) of the type Fe0/H2O2/UV and heterogeneous modified photo Fenton process (HMPFP) of the type Fe0/ammonium persulfate (APS)/UV. The influence of various reaction parameters like pH, catalyst loading, concentration of the oxidants and the influence of inorganic anions such as Chloride (Cl−) and Sulfate (SO42−) ions on processes were investigated. Quenching of the hydroxyl radical by inorganic anions was confirmed by the decrease in the degradation rate constant for the HAPFP from 3.33×10−2 to 0.19×10−2 (for Cl− (1M)) and 0.29×10−2min−1 (for SO42− (1M)). Similar decrease in rate constant for HMPFP is from 4.67×10−2 to 0.41×10−2(for Cl− (1M)) and 0.51×10−2min−1 (for SO42− (1M)) process. The combined effect of concentration of sulfate and chloride ions on the rate constant for the degradation of ARS with APS and H2O2 as oxidants is investigated. The initial degradation mechanism involves the cleavage of a quinone group to catechol as detected by UV–visible and GC–MS analysis.