Dry and wet ozonation of denim: degradation products, reaction mechanism, toxicity and cytotoxicity assessment

Sarra Ben Hamida, Sidra Iftekhar, Indu Ambat, Varsha Srivastava, Mika Sillanpää, Zahra Amri, Neji Ladhari

Index: 10.1016/j.chemosphere.2018.03.199

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Abstract

The study aims to identify the denim ozonation by-products under different operating conditions and investigate the chemical toxicity of these compounds via the inhibitory effect of the sample on the light emission of bioluminescent bacteria (Vibriofischeri) and on human health using the HepG2 human hepatoma cell line. Various by-products in treated denim extract were detected w gas chromatography-mass spectrometry (GC-MS) analysis. The results revealed that the main oxidation by-product was isatin (1H-indole-2,3-dione), which formed in excess amounts on wet ozonated denim. It was observed that this compound showed more toxicity when high ozone concentrations were used, especially in the presence of moisture. It exhibited a considerable antibacterial activity. EC20 and EC50 average values of 5.55% and 13.47% were obtained with a wet ozonation rinse bath at 48g/N·m3, which makes it hazardous to aquatic environments.