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Crystal violet dye removal from aqueous solution by electrocoagulation

Due to their wide range of colour pigments and uniform colouring, synthetic dyes currently dominate the market with a production of 8×10 5 tonnes per year [1]. Synthetic dyes are used in various industries such as textile, food processing, pharmaceutical, cosmetic, pulp and paper, etc., resulting in a large amount of wastewater contaminated with dye residues. Due to their complex structure, which makes them very stable and difficult to degrade, they have a negative impact on water quality. Their presence in surface waters causes them to block light transmission, impair photosynthesis of plants and algae in water, and reduce dissolved oxygen in water [2]. Some studies have shown that synthetic dyes contribute to carcinogenicity and mutagenicity in various species [3, 4]. Therefore, much attention is paid to the methods for their removal. In this study, electrocoagulation (EC) was used as an alternative method to remove crystal violet dye using AA2007 aluminium alloy electrodes. The simulated wastewater solution consisted of 4 mg/L crystal violet dye with the addition of 2 g/L NaCl as a supporting electrolyte. The pH of the electrolyte was adjusted to 3.2, 5.5 and 7.0, and the experiments were performed with current densities of 16, 24, and 32 mA/cm2 . The results showed that this method can be successfully used for the treatment of wastewater contaminated with dyes reaching more than 98% of removal efficiency after 50 min of treatment with the highest current density applied. References: [1] G.F. Kobiri, Synthetic Dye Application in Textiles: A Review on the Efficacies and Toxicities Involved, Textile & Leather Review. (2022)5:180-198. https://doi.org/10.31881/TLR.2022.22. [2] Y. Liu, C. Li, J. Bao, X. Wang, W. Yu, L. Shao, Degradation of azo dyes with different functional groups in simulated wastewater by electrocoagulation, Water 2022, 14, 123. https//doi.org/10.3390/w14010123. [3] F.R. Abe, A.M. Soares, D.P. de Oliveira, C.A. Gravato, Toxicity of dyes to zebrafish at the biochemical level: Cellular energy allocation and neurotoxicity. Environ. Pollut. 2018, 235, 255–262. https://doi.org/10.1016/j.envpol.2017.12.020. [4] P. Rajaguru, L. J. Fairbairn, J. Ashby, M. A. Willington, S. Turner, L. A. Woolford, N. Chinnasamy, J. A. Rafferty, Genotoxicity studies on the azo dye Direct Red 2 using the in vivo mouse bone marrow micronucleus test, Mutation Research 444(1) (1999) 175-180. https://doi.org/10.1016/S1383- 5718(99)00081-9.

crystal violet dye ; wastewater treatment ; electrocoagulation ; aluminium electrodes

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