An efficient measure for controlling pollution in the dye industry: Experimental and DFT investigations on direct determination of 3-(N,N-diethylamino)acetanilide

Abstract

The rapid expansion of the dye industry has led to severe environmental pollution. The lack of real-time direct determination methods for dye intermediates is a key factor in high pollution emissions and low product quality in the continuous synthesis of dyes. This study proposes an accessible, fast, and precise approach for the clean and direct determination of 3-(N,N-Diethylamino)acetanilide (DEAA), a dye intermediate used in the synthesis of the azo dye Disperse Violet 93:1. For precise DEAA quantification, we developed a multi-pathlength and multi-wavelength coupled differential photometric approach based on the absorption spectra characteristics of DEAA at various concentrations and optical pathlengths. A relatively stable analytical sensitivity (0.5671–66.2630) and a large concentration range of 0.01–11% were obtained. Compared to the traditional single-optical pathlength and single-wavelength quantification, this new method possessed 119 times higher sensitivity. The maximum quantitative relative error decreased from 9.17% to 2.44%. The orbital contribution and distinctive peak electronic excitation mechanism of DEAA were uncovered using TD-DFT. By comparing the oscillator strength and peak position variations between the target DEAA and coexisting sulfuric acid, the unique spectral behavior of DEAA, such as its high sensitivity and selectivity, was explained. In addition to providing a reference for real-time industrial dye and intermediate monitoring, this study lays the methodological groundwork for future research. In light of the new method's short time consumption and non-secondary pollution benefits, we further believe it will be crucial in controlling the industrial synthesis process in order to improve product quality, resource conversion efficiency, and effectively prevent excessive pollution generation.