Complex extraction of sulfonate dyes from wastewater and the effect of dye structure on extraction performance

ABSTRACT

In this study, the influences of sulfonate dye structure on the extraction rate, the reaction mechanism, and the complex ratio were studied. The parent structure and the number of sulfonic acid groups of sulfonate dyes have a great effect on extraction performance, whilst the molecular weight has a small effect on extraction performance. The results indicate that the extraction rate of azo dyes remains above 80% at the aqueous-organic phase ratio of 7:1, but the extraction rate of two anthraquinone dyes decreases to 54.9% and 34.9%, respectively; and the fewer the number of sulfonic acid groups of the dye, the better the extraction performance under the condition of insufficient extractant, the extraction rate of Direct Grey D and Acid Red M is over 82%. A complete set of methods for determining the ratio of the extractant and the dye was determined using the distribution coefficient method. The interaction between Telon Yellow 4 R and trioctylamine is ionic association and hydrogen bonding association, and the complex ratio between the dye and the extractant is about 2:1. In summary, dye structure has a big impact on the extraction performance, which should be taken into account in actual application.

KEYWORDS:

• Complex extraction
• sulfonate dyes
• wastewater
• extraction rate
• distribution coefficient

Acknowledgments

The authors would like to thank Dystar Trading Co. Ltd, Jiaying Chemical Co. Ltd. and Jinshungyu Technology Co. Ltd. for providing the reactive dyes, the acid dyes, and the direct dyes, respectively.

Disclosure statement

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

Statement of novelty

1. The effect of sulfonate dye structure on the complex extraction was studied systematically.

   1. The parent structure and the number of sulfonic acid groups of sulfonate dyes have great effects on extraction performance.

   2. Azo dyes and the dyes with less sulfonic acid groups have better extraction performance.

2. A method for determining the complexation ratio between the extractant and the dye was proposed.

3. The extraction of trioctylamine on Telon Yellow 4 R is achieved through ion bonding and hydrogen bonding, which was proved by FT-IR.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/01496395.2023.2248368