Evaluation of the photocatalytic activity of TiO2 films by using a microfluidic reactor

ALFANO, ORLANDO M.; MARTIN, MARCELA V.; SATUF, MARÍA L.

Córdoba

Congreso; II Brazil-Argentine Microfluidics Congress. V Congreso de Microfluídica Argentina; 2019

Microfluidica Argentina, UNC, FAMAF

Over recent years, the hormone 17--ethinylestradiol (EE2) has been found in the discharge waters of sewage treatment plants, indicating the incomplete removal of this pollutant by conventional methods. EE2 is a synthetic hormone with estrogenic activity, capable of altering the endocrine system of living organisms. Photocatalysis with titanium dioxide (TiO2) is an advanced oxidation process that has been successfully applied for the degradation of organic species resistant to conventional water treatment methods, including the removal of natural and synthetic hormones. The use of microreactors for the study of photocatalytic reactions has recently gained much attention, since they allow more accurate control of operation variables and more uniform irradiation through the entire reaction space compared to conventional photoreactors. Furthermore, microreactors are highly beneficial for testing expensive catalyst materials because only small quantities are needed. With a simple setup, involving low reagent consumption and short test times, rigorous evaluation of the activity of different photocatalytic films can be achieved. In this work, we evaluate the photocatalytic activity of pure and cerium-doped TiO2 films for the degradation of EE2 in aqueous solution using a continuous flow, planar microreactor. It has been demonstrated that small amounts of cerium can improve the activity of TiO2 catalysts. The reaction chamber has a volume of 232 μL. One of its walls is composed of a borosilicate glass plate (5.8 cm x 2 cm), which was used as a support to immobilize the catalysts by the dip coating technique. The degradation of 9 mg/L of EE2 aqueous solutions under monochromatic LED sources of 365 nm was evaluated. Experiments were carried out with 3 coatings of the catalysts, at initial pH 8 and with a flow rate of 17 L.min-1. The concentration of the hormone was determined by HPLC. The highest EE2 degradation, 59.8%, was achieved with the cerium-doped film, whereas 55.0% degradation was obtained with the undoped film. The benefits of employing a microreactor for catalyst screening is demonstrated, allowing the study of different operating conditions in a simple and fast way, and with minimum consumption of reagents.