Assessment of the Effect of Shade on the Performance of Photocatalyst-Dyed Cotton

This project focuses on immobilizing the photocatalyst Eosin Y onto cotton fabric and evaluating its potential as a reusable, solid-supported catalyst for photoredox reactions. In the first phase, Eosin Y was successfully dyed and immobilized onto pre-treated cotton, as indicated by the bright pink coloration of the fabric. This was performed by first converting Eosin Y from a carboxylic acid form to a reactive acid chloride form using N,N′-Dicyclohexylcarbodiimide (DCC) as the coupling agent. Thin Layer Chromatography (TLC) was performed to monitor the formation of the acid chloride derivative; however, no significant difference in Rf values was observed with or without the use of DCC. The acid chloride form was then reacted with cotton samples to covalently attach Eosin Y to the surface of the fabric. Repeatability of the process was tested, and samples showed slight shade variations, reflecting natural differences in dye uptake during the immobilization process. Tests to further confirm the covalent attachment of the photocatalyst to cotton are in progress.

In the second phase, the Eosin Y-treated cotton was tested for its photocatalytic activity in the oxidation of benzyl sulfide. The reaction mixture containing benzyl sulfide and the photocatalyst-attached cotton was illuminated with blue light (450 nm) over 72 hours. TLC was used to track the reaction progress, and it showed the formation of benzyl sulfoxide, demonstrating that the photocatalytic system is active.

The next steps of this project will focus on standardizing the immobilization procedure by increasing replicates, improving fabric submersion, and adjusting both reaction steps to achieve more uniform dye loading. After optimization, this project will advance to monitor sulfide oxidation kinetics and evaluate catalyst reuse cycles to assess durability and long-term activity. Together, this study aim to determine the viability of cotton-supported Eosin Y as a sustainable solid-phase photocatalyst.