Degradation of 4-chlorophenol by photocatalysis with carbon self-doped and iron co-doped TiO2 films: radiation absorption properties and performance evaluation in a microrreactor

OCHOA RODRÍGUEZ, PABLO ; MARTIN, MARCELA V.; EUSEBI ANA LISA; EIMER, G.; ELÍAS, V.; SATUF, MARÍA L.

Buenos Aires

Congreso; 11th World Congress of Chemical Engineering; 2023

Asociación Argentina de Ingenieros Químicos

The design of nanostructured solids by eco-compatible routes is one of the current strategies to solve the problem of water contamination with persistent and refractory organic substances, such as 4-chlorophenol (4CP). Furthermore, microreactors provide an excellent platform for photocatalytic kinetic studies based on the advantages of the microscale: laminar flow, short molecular diffusion distances, uniform irradiation, large surface to volume ratio, and accurate control of operation variables. Additionally, small amounts of catalysts and reagents are needed, and waste generation is minimal [1].The aim of this work is to use a microreactor to evaluate the activity of photocatalytic films of carbon self-doped and iron co-doped TiO2 for the degradation of 4CP in water. The performance of the films was objectively evaluated by means of the quantum efficiency parameter, which relates the moles of pollutants degraded per mole of photons absorbed by the catalyst.Degradation experiments were carried out in a planar, continuous flow microreactor. The reactor window is a borosilicate glass plate, which was used as support to immobilize the films. The suspensions to make the coatings were those obtained at the end of a synthesis hydrothermal treatment at 150 °C, of the system composed of titanium (IV) n-butoxide as a TiO2 precursor, and iron (III) acetylacetonate in the appropriate amount to reach a level of Fe 0.1 wt%. The organic Ti source can further generate a carbon self-doping (sample 150FeMT). Subsequently, some plates were calcined at 400ºC to eliminate the carbon component and used as reference (sample 400FeMT).The degradation of aqueous solutions of 4CP 100 M was evaluated under simulated sunlight. The radiation flux incident at the photocatalytic films was measured with a UV–vis mini-spectrophotometer, obtaining an average value of 5.47 mW cm-2 in the range of 300–500 nm. The concentration of 4CP in the samples was determined by HPLC. Spectral diffuse transmittance and reflectance measurements of the films were carried out to evaluate the fraction of radiation absorbed by the coatings. The 150FeMT film showed higher radiation absorption than the reference 400FeMT, and it was more efficient in terms of pollutant degradation, with a quantum efficiency of 0.44 %, while the reference achieved an efficiency value of 0.25 %. Some authors propose that the presence of a metallic element, together with carbon, allows to achieve the synergy that impacts on a better performance of the film [2].In this manner, an interesting technology with lower environmental impact and greater sustainability for the remediation of water polluted with 4CP is presented.