Microfluidic platform for screening the activity of immobilized photocatalysts for degradation of water pollutants in flow†

Abstract

Photochemistry screening platforms can accelerate the discovery and development of novel photocatalysts for water remediation. This study presents the design, characterization, and optimization of an innovative flow-based screening platform for evaluating immobilized photocatalysts in the photodegradation of water pollutants. The compact system is engineered with four 3D-printed polymeric microreactors and a multi-wavelength LED light source capable of emitting at four distinct wavelengths. Therefore, the platform design allows at least 16 unique testing conditions through light source rotation. The performance of the microfluidic platform was evaluated via the photocatalytic degradation of imidacloprid, a pesticide, using P25/20 TiO₂ immobilized as a thin film. The results demonstrated a consistent degradation efficiency of approximately 35% at 395 nm with negligible variation across the four microreactors and no dependence on the testing order at 395, 409, 413, and 443 nm. During the wavelength-dependent screening, the photocatalytic film activity did not decrease after 6 hours of operation and under five successive illumination conditions, while only 46 mg of photocatalyst and 21 mL of imidacloprid aqueous solution were consumed. Moreover, automated dynamic flow and dynamic irradiation were used to optimize degradation efficiency and a guide on how to use them to improve energy efficiency and overcome common limitations of in-flow testing was provided. This microfluidic platform diminishes manual effort and enables efficient and sustainable photocatalytic studies while establishing itself as a promising tool for the automated screening of immobilized photocatalysts.