Evaluation of Photocatalytic Performance of Nano-Sized Sr0.9La0.1TiO3 and Sr0.25Ca0.25Na0.25Pr0.25TiO3 Ceramic Powders for Water Purification

Abstract

Water pollution is a significant issue nowadays. Among the many different technologies for water purification, photocatalysis is a very promising and environment-friendly approach. In this study, the photocatalytic activity of Sr0.9La0.1TiO3 (SLTO) and Sr0.25Ca0.25Na0.25Pr0.25TiO3 (SCNPTO) nano-sized powders were evaluated by degradation of pindolol in water. Pindolol is almost entirely insoluble in water due to its lipophilic properties. The synthesis of the SCNPTO was performed using the reverse co-precipitation method using nitrate precursors, whereas the SLTO was produced by spray pyrolysis (CerPoTech, Trondheim Norway). The phase purity of the synthesized powders was validated by XRD, while HR-SEM revealed particle sizes between 50 and 70 nm. The obtained SLTO and SCNPTO powders were agglomerated but had relatively similar specific surface areas of about 27.6 m2 g−1 and 34.0 m2 g−1, respectively. The energy band gaps of the SCNPTO and SLTO were calculated (DFT) to be about 2.69 eV and 3.05 eV, respectively. The photocatalytic performances of the materials were examined by removing the pindolol from the polluted water under simulated solar irradiation (SSI), UV-LED irradiation, and UV irradiation. Ultra-fast liquid chromatography was used to monitor the kinetics of the pindolol degradation with diode array detection (UFLC–DAD). The SLTO removed 68%, 94%, and 100% of the pindolol after 240 min under SSI, UV-LED, and UV irradiation, respectively. A similar but slightly lower photocatalytic activity was obtained with the SCNPTO under identical conditions, resulting in 65%, 84%, and 93% degradation of the pindolol, respectively. Chemical oxygen demand measurements showed high mineralization of the investigated mixtures under UV-LED and UV irradiation.