Improving the Degradation Kinetics of Industrial Dyes with Chitosan/TiO[sub.2]/Glycerol Films for the Sustainable Recovery of Chitosan from Waste Streams

This study investigates the potential of a combined photocatalysis–adsorption approach to effectively degrade near wash yellow (NWY), a commonly used and highly persistent dye in the textile industry, notorious for its challenging treatment and removal from wastewater due to its colorfastness. A chitosan–glycerol (CTiG) film combined with titanium dioxide was examined in both batch and continuous-flow experiments under visible solar irradiation. The results show that this combination was more effective than a pure chitosan film (60%) or chitosan–glycerol film (63%), with up to 83% degradation of NWY achieved in just 60 min of visible solar irradiation. The kinetics of the film were evaluated using both pseudo-first-order and Langmuir–Hinshelwood kinetic models. The rate constant values (k, min[sup.−1] ) decreased with increasing NWY concentration from 20 to 80 mg/L, and k was found to be greater than twice as high under visible solar irradiation as it was in the dark. The Langmuir–Hinshelwood model’s K[sub.LH] (reaction rate constant) and K[sub.L] (adsorption coefficient) values were 0.029 mg/L·min and 0.019 L/mg, respectively. The optimal conditions for NWY degradation were found to be 4% TiO[sub.2] to chitosan ratio, glycerol/chitosan ratio of 40%, and a pH of 7. In the continuous-flow model, the CTiG film was submerged in an 8 L NWY solution (80 mg/L) and degraded at a rate of 22.6 mg NWY/g film under natural sunlight. This study contributes to the development of effective and sustainable methods for the degradation of dyes from textile industry wastewater.