Physicochemical Modifications and Decolorization of Textile Wastewater by Ozonation: Performance Evaluation of a Batch System

ABSTRACT

This is an experimental study on the decolorization efficiency and the degradation of organic compounds from textile wastewater by the ozonation process in a batch system. The effects of different sample volumes of textile wastewater over time were investigated. The experiments were performed in a 1 L glass reactor with a magnetic stirrer and a bubble diffuser at the bottom to feed the ozone. The applied cumulative ozone dosage varied at 120 gO₃ L⁻¹, 60 gO₃ L⁻¹, and 30 gO₃ L⁻¹, and the total interaction time for each test was 1 h. To investigate the physicochemical properties of the textile wastewater (solid and liquid phases) before and after the treatment, multiple analytical characterization methods were used: Thermal Gravimetric Analysis, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, and Spectrophotometer. The most perceptive change was observed in the color of the liquid medium, which turned from black to transparent, and a visual color number indicator known as DurchsichtFarbZahl (DFZ) was used for the evaluation of this process. Absorbance values decreased about 3.5 times after 5 min of treatment with a 0.15 L sample volume, and these values differed for tests with larger sample volumes. FTIR spectroscopy demonstrated that the bands’ intensities associated with the C − H, C − N, and C − O decrease during treatment. On the other hand, it was possible to conclude that combining treatment methods to improve the degradation of persistent compounds after the ozonation process is necessary. Finally, the ozonation of the textile wastewater proved to be effective at removing color due to its high reaction capacity.

Graphical Abstract

KEYWORDS:

• Decolorization
• ozonation
• textile wastewater
• treatment

Acknowledgments

The authors acknowledge the fellowship awarded by the National Council for Scientific and Technological Development (CNPq) to Eduardo Sant’Ana Petraconi Prado [grant number 141130/2021-0]. We also thank the support given by the National Institute for Space Research (INPE) and Plasmas and Processes Laboratory of the Aeronautics Institute of Technology (LPP-ITA).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.

Additional information

Funding

This work was supported by the National Council for Scientific and Technological Development (CNPq) [141130/2021-0].