Work

The Role of Titanium Species in Ti-SBA-15 Materials for the UV–Photocatalytic Degradation of Acetaminophen in Water

Year: 2026

Type: article

Abstract: Water contamination by acetaminophen, a compound difficult to remove via conventional treatments, has become a growing environmental concern due to its excessive consumption in recent years. Among emerging methods for removing this pollutant, heterogeneous photocatalysis is a promising option that enables catalyst recovery and reuse. In this research, Ti-SBA-15 materials with different Si/Ti molar ratios were synthesized by a one-step sol–gel method to improve Ti dispersion within the SBA-15 silica framework. A detailed characterization of the materials was carried out using XRD, SEM, ICP-OES, N2 physisorption, UV-Vis-DRS, XPS, and zeta potential techniques. The results showed that the characteristic hexagonal mesoporous structure of SBA-15 was largely preserved at high Si/Ti ratios, while ICP-OES analysis showed that the synthesis method allowed Ti incorporation close to the theoretical Si/Ti molar ratio for most synthesized materials. As the Ti content increased, the specific surface area decreased, whereas the band gap energy increased. The UV-Vis-DRS spectrum showed an absorption band around 230 nm, which is commonly associated with ligand-to-metal charge transfer transitions in isolated Ti species with tetrahedral coordination. Together with the XPS results, these findings suggest that the Ti incorporated into the silica framework is predominantly in tetrahedral coordination. Small amounts of Ti in Ti-SBA-15 materials are sufficient to promote photocatalytic acetaminophen degradation, without requiring significant anatase formation. Catalyst dosage and solution pH significantly influenced system performance, with higher degradation rates observed under acidic conditions. However, the rapid disappearance of acetaminophen did not directly translate into high mineralization, as aromatic intermediates are difficult to break down into carboxylic acids. Consequently, the maximum mineralization achieved was 50%, obtained with a catalyst concentration of 50 mg/L at pH 6. The proposed reaction scheme successfully predicted the experimental data. These results show that the Ti-SBA-15 system possesses a high capacity for degrading acetaminophen; however, complete mineralization is limited by the slow oxidation rate of aromatic intermediates, making the control of subsequent degradation stages a key factor in improving the overall efficiency of the photocatalytic process.

Source: Catalysts

DOI: 10.3390/catal16100892