In situ Decolorization Monitoring of Textile Dyes for an Optimized UV-LED/TiO2 Reactor

Abstract

Heterogeneous photocatalysis, using photocatalysts in suspension to eliminate diverse contaminants, including textile wastewater, has several advantages. Nevertheless, current absorbance and decolorization measurements imply sample acquisition by extraction at a fixed rate with consequent photocatalyst removal. This study presents online monitoring for the decolorization of six azo dyes, Orange PX-2R (OP2), Remazol Black B133 (RB), Procion Crimson H-EXL (PC), Procion Navy H-EXL (PN), Procion Blue H-EXL (PB), and Procion Yellow H-EXL (PY), analyzing the spectrum measured in situ by using the light scattering provided by the photocatalyst in suspension. The results obtained have corroborated the feasibility of obtaining absorbance and decolorization measurements, avoiding disturbances in the process due to a decrease in the volume in the reactor.

Performance analysis and methodology for replacing conventional lamps by optimized LED arrays for photocatalytic processes

“…In the last years, some authors have proposed the use of UV-LEDs in order to carry out the photocatalysis processes (Jamali et al, 2013;Jo and Tayade, 2014b;Kim et al, 2016;Matafonova and Batoev, 2018;Tapia-Tlatelpa et al, 2019). In this regard, most of the current literature focuses on the direct replacement of the conventional ultraviolet lamp by LED arrays (Ghosh et al, 2009;McCullagh et al, 2011;Shie et al, 2008), without any discussion regarding to its optimal distribution.…”

Automated Monitoring System for Suspended Photocatalytic Batch Reactions Based on Online Circulatory Spectrophotometry

“…To address the limitations of sampling and pretreatment, recent research has focused on in situ real-time monitoring, involving direct spectral monitoring of the reactor using various optical methods to acquire kinetic data without sampling. For instance, Tapia-Tlatelpa et al [ 14 ] monitored the photocatalytic degradation kinetics of dyes on TiO 2 using light scattering spectroscopy. In contrast, Rößler et al [ 15 ] achieved the automated monitoring of photo-induced synthesis reactions through in situ Raman and UV-Vis spectroscopy probes.…”

“…This method acquires absorbance at different wavelengths and separates the reaction and detection, providing the benefits of easy experimental operation and minimal interference with monitoring signals caused by the excitation light and stirring. However, this approach encountered problems, including signal noise from bubbles (SNB) [ 26 ], and solid particle deposition on the inner wall of pipelines (PDP) and on the windows of a flow cell (PDW) [ 14 , 27 , 28 ]. SNB refers to the sudden increase in signal intensity of absorbance caused by the presence of bubbles during monitoring.…”

UV-Based Advanced Oxidation Processes of Remazol Brilliant Blue R Dye Catalyzed by Carbon Dots

“…Coupling UV with H 2 O 2 and S 2 O 8 2− will generate the hydroxyl radical and, in the case of S 2 O 8 2− , the sulfate radical, and these radical species are active oxidants in the dyes' degradation processes [11]. Besides these two homogeneous catalysts, the heterogeneous photocatalyst and semiconductor TiO 2 is also commonly used as an AOP, and hydroxyl radical is produced according to the following mechanism [14][15][16][17][18]:…”