In situ dynamic monitoring of the photodegradation process through differential absorption spectroscopy

Abstract

Photocatalytic degradation is considered a promising method to remove pollutants from the environment. Exploring the photodegradation mechanism and monitoring the degradation process is important for the development of photocatalysts with improved performance. A dynamic in situ monitoring system that can precisely reflect the catalytic performance would eliminate inefficiencies and decrease error observed in traditional sampling methods. Here, a dynamic in situ monitoring system is developed by utilizing differential absorption spectroscopy. The variation in absorbance is continuously monitored, as the solution is constantly circulated through the spectrometer without interrupting the catalytic process, making it economical and portable. The in situ detection module has been demonstrated with the degradation of Rhodamine B and Methyl Orange dyes using Cs₃Bi₂Br₉/TiO₂ and Cs₂AgBiCl₆ as photocatalysts. Our system is able to provide a large number of continuous data of absorption spectra and perform in situ and real-time monitoring. This technique is flexible to assemble with different photodegradation systems and has the potential to be widely applied to monitoring dynamic photocatalytic degradation processes with significant advantages over the traditional methods.