Differential pulse voltammetry monitoring of the photocatalytic performance of molecularly imprinted valsartan under LED irradiation

Abstract

The pervasive presence of valsartan (VAL), a widely used antihypertensive pharmaceutical compound, in aquatic environments has prompted concerns due to its low biodegradability and potential environmental impact. Emerging contaminants such as VAL necessitate advanced remediation methods beyond conventional wastewater treatments. In this study, the degradation of VAL in water matrices was explored utilizing a combination of molecular imprinting (MI) and heterogeneous photocatalysis, excited by different light-emitting diodes (LEDs) at 407 nm (40.55 W/m⁻²(−|-)), 530 nm (83.04 W/m⁻²(−|-)), and 355 nm (16.43 W/m⁻²(−|-)). The concept of MI was applied in the preparation of a TiO₂-based photocatalyst bearing VAL as a template. The encapsulation was carried out through an acid-catalyzed sol–gel route. The photocatalyst was characterized by surface area, pore volume, zeta potential, Fourier transform infrared spectroscopy, X-ray diffraction, and band gap measurements. The results obtained indicate that the radiation energy in the visible region is effective for degrading VAL. More specifically, the results obtained from differential pulse voltammetry indicate the consumption of VAL present in the modified electrode as well as the oxidation of the tertiary amine group of the molecule of VAL in addition to interactions between the drug and the network structure of the MI under light stimulation. Under the experimental conditions, the present photocatalyst system demonstrates the feasibility of VAL degradation under LED irradiation (change in anodic current was 15 % after 30 s under stimulation by LED light in the visible region). The viability of combining both concepts in the case-study of VAL as pollutant target added by the evaluation of the potentiality of employing LED irradiation.