Kinetic effects of cationic surfactants on the photocatalytic degradation of anionic dyes in aqueous TiO2 dispersions. (5th December 2022)

• Record Type: Journal Article
• Authors: Germani, Raimondo; Mancinelli, Matteo; Roselli, Arianna; Tiecco, Matteo; Fantacci, Simona; di Bona, Stefano; Del Giacco, Tiziana
• Is Part Of: New journal of chemistry. Volume 47:Number 1(2023)
• Page Start: 392
• Page End: 401
• Publication Date: 2022-12-05
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/d2nj04715b
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : The synergistic catalytic effect of surfactants is highlighted in the photodegradation of Orange G and Eosin Y by TiO2 at alkaline pH. Abstract : In this study, oxidative degradation of Orange G (OG) and Eosin Y (EY) dyes with TiO2 as the catalyst was explored in air-equilibrated aqueous dispersions under UV light irradiation. To determine the optimal operating conditions for degradation, various effects were investigated, such as the pH of the dye dispersion, the addition of cationic surfactants and the specific additive. The photodegradation efficiency of both dyes was significantly enhanced at alkaline pH, particularly in the presence of tetraalkylammonium bromide surfactants, as they promote a mutual interaction between the dye and TiO2 surface, otherwise prevented due to their negative charge under basic conditions. The surfactant concentration also played an important role, because it influences the state of surfactant aggregation on the semiconductor surface. The kinetic trend of the fragmentation process was strongly affected by different hydrophobic and electrostatic interactions that OG and EY and their derivative intermediates are able to establish with surfactant/TiO2 in various forms of aggregation, as well as by their redox properties. Density functional theory (DFT) calculations of charge distribution and Gibbs free energy changes of solvation, performed on optimized molecular geometry, were useful to support and rationalize the surfactant involvement in the degradation process.