Photocatalytic removal of textile dyes: Analytical strategies for post-degradation evaluation

Abstract

Textile dye pollution poses a serious threat to aquatic ecosystems due to the complex, stable and often toxic nature of synthetic dyes. Photocatalytic degradation, a green and efficient advanced oxidation process, has emerged as a promising solution for removing persistent dye pollutants. This systematic review critically explores the advancements in photocatalytic degradation of textile dyes, highlighting various catalysts, including semiconductors, doped semiconductors and composite nanomaterials. Key operational parameters, such as pH, light intensity, catalyst dosage and dye concentration, are examined for their influence on degradation efficiency. Additionally, this review focuses on post-degradation analytical strategies to evaluate the extent of mineralization and toxicity reduction. Identifying and analyzing degradation products is crucial to ensure complete mineralization and detect any harmful intermediates. However, limited knowledge of suitable analytical techniques often leads to challenges in accurate identification, which can risk misinterpretation or overlook key byproducts. Techniques such as UV–Vis spectroscopy, Raman spectroscopy, TOC analysis, HPLC, FTIR, ICP-MS and GC–MS are discussed in detail for their roles in monitoring dye breakdown, identifying intermediate products and assessing complete mineralization. The interplay between photocatalyst properties, operational parameters and analytical methodologies is highlighted, providing insights into optimizing degradation processes and ensuring reliable assessment of dye removal. By integrating photocatalytic performance with robust post-degradation evaluation, this review aims to guide future research toward more efficient, sustainable and analytically sound strategies for wastewater treatment in the textile industry.