Zinc-Aluminium Layered Double Hydroxide-Based Materials for Pollutant Removal from Water SolutionsTrobec, Klemen (Avtor) Cerc Korošec, Romana (Mentor) L. Bianchi, Claudia (Komentor) layered double hydroxidelayered double oxidethin filmsorptionphotocatalysisLayered double hydroxides (LDHs) are inorganic materials consisting of positively charged mixed metal hydroxide layers with charge-balancing anions and water molecules in the interlayer space. Their calcination yields layered double oxides (LDOs), which can combine a high specific surface area with semiconductor properties and can therefore act both as sorbents and as photocatalysts for the removal of organic pollutants from water. The aim of this work was to prepare Zn–Al LDH-derived LDOs in powder and thin-film form and to determine how the anion intercalated in the LDH precursor affects their sorption and photocatalytic properties. A chloride-intercalated Zn–Al LDH (ZnAl-Cl) was synthesized by coprecipitation at constant pH and converted by ion exchange into the carbonate-intercalated form (ZnAl-CO3); both were calcined at 600 °C to the corresponding oxides (ZnAl-Cl-600, ZnAl-CO3-600). Thin films were deposited on glass substrates by dip-coating from colloidal sols, obtained by peptization of the LDHs with glacial acetic acid. In the powder form, materials were characterized by X-ray diffraction, scanning electron microscopy, nitrogen physisorption, FTIR, UV-Vis diffuse reflectance spectroscopy and electrokinetic measurements, and tested in sorption and UV-A photocatalytic experiments with gallic acid (GA), 3,4,5-trimethoxybenzoic acid (TMBA), ibuprofen and amoxicillin. The latter properties of the prepared materials were tested also in thin-film form (films were deposited onto object glass slides); their thickness and morphology were determined with scanning electron microscopy. Calcination gave a crystalline mixture of ZnO and ZnAl2O4 from ZnAl-Cl, but a poorly crystalline ZnO phase from ZnAl-CO3. Only the latter reconstructed the layered structure upon exposure to a solution containing its precursor’s interlayer anion. The two oxides had comparable specific surface areas, band-gap energies corresponding to absorption in the UV-A region and isoelectric points in the basic region of the pH scale. Sorption proved to be governed by the structure of the pollutant rather than by electrostatic interaction alone: GA and amoxicillin were strongly sorbed, while TMBA and ibuprofen, whose functional groups apparently have a much lower tendency toward surface complexation and hydrogen bonding, were not. ZnAl-Cl-600 was the more efficient material in both respects, but was substantially deactivated by repeated use with GA, which was attributed to surface-bound organic species and to a partial reconstruction of the layered structure. The thin films were active, although at lower rates than the corresponding powders.20262026-10-01 09:55:05Magistrsko delo/naloga189090VisID: 25654sl