Desenvolvimento de um fotoreator para aplicação em síntese fotoquímica de nanopartículas e estudo de fotocatálise

Abstract

The present work presents the construction and characterization of a semi-automated photoreactor based on Arduino, operating in batch mode, serving as a versatile and accurate tool for various photochemical applications. The photoreactor was evaluated in terms of photon flux and reactor power parameters, demonstrating an approximate quantum yield of 80% with different tested irradiation sources. The system provides photon fluxes (If) of 2.42x1019 , 5.64x1018, and 1.31x1017 photons/s, and reactor powers (Iw) of 275, 316, and 374 mW/cm2 for UV-A, UV-B, and UV-C lamps, respectively. The photoreactor allows operation with different radiation sources, temperature control, and exposure time, displays information on an LCD panel, and can incorporate additional sensors/actuators in its design. Specifically, the temperature sensor was calibrated and demonstrated efficient energy transfer through the outer coating, maintaining a constant temperature of the reaction mixture during operation, showing that automation with Arduino facilitates usability and enhances experimental reliability. With its advanced features and precise controls, the photoreactor stands out as a valuable tool for photochemical studies, including inorganic or organic photochemical synthesis, degradation of organic materials, and heterogeneous photocatalysis. Finally, to demonstrate its functionality, the photochemical synthesis of gold nanoparticles (AuNP) was performed, as well as their utilization in the degradation of Safranin dye. Firstly, the photochemical synthesis of AuNP was carried out under different UV-A exposure times and temperature control conditions. It was possible to verify that the photochemical process, combined with thermal control of the reaction mixture, allowed obtaining AuNP with controlled particle size. Transmission electron microscopy (TEM) analysis showed that a temperature of 70°C and an exposure time of 20 minutes are sufficient for obtaining AuNP with an average size of 15.6 ± 4.0 nm. Lastly, in the dye photodegradation, it was observed that the high power of the photoreactor is capable of degrading the dye with an approximately 96% degradation rate using a UV-C lamp.