Determinação de frações em misturas de corantes têxteis usando espectrometria UV-Vis combinada à regressão por mínimos quadrados parciais e análise por componentes principais

Abstract

The contamination of surface waters by textile dyes, such as Remazol Blue, Remazol Black, and Remazol Red, poses a threat to aquatic fauna, flora, and ecosystem stability. The effective removal of these dyes is crucial and challenging, requiring technologies to treat textile effluents. Advanced Oxidative Processes (POAs) have excelled in removing persistent organic pollutants in low-concentration aqueous effluents due to the formation of highly reactive hydroxyl radicals. The H2O2/UV process, which combines hydrogen peroxide (H2O2) and ultraviolet radiation (UV), shows promise in degrading persistent compounds in effluents contaminated by resistant organic pollutants. Additionally, multivariate calibration is a powerful technique widely used to simultaneously determine multiple analytical variables through a single statistical model, providing a deeper understanding of complex phenomena and more precise decision-making. Methods like PLS and PCA are widely employed to analyze and interpret the relationship between dependent and independent variables, offering valuable insights into chemical data analysis. This study combined PLS and PCA with UV-Vis Spectroscopy to determine fractions of textile dyes in complex solutions, emphasizing the need for rigorous validation. In addition to deepening the understanding of challenges in removing organic pollutants from industrial effluents, it sought sustainable solutions for protecting aquatic ecosystems and water quality. The detection and quantification of dyes through univariate calibration proved unfeasible due to high spectral overlap, highlighting the necessity of multivariate approaches. Multivariate calibration procedures with PLS 1 exhibited good performance, albeit with relative prediction errors (REP) above accepted standards, especially for the black dye. In degradation tests, the H2O2/UV-C process completely removed textile dyes, with color removal rates of 79.07%, 88.69%, and 96.22% after 30 minutes (Blue, Red, and Black, respectively), positively impacting effluent treatment. Principal Component Analysis (PCA) identified kinetic patterns, contributing to treatment improvements. Thus, these findings underscore the significance of multivariate calibration and the effectiveness of dye removal, indicating surmountable challenges in calibration precision.