The aim of this work was to develop hybrid TiO₂/ZIF-8 photocatalysts and test their activity for the removal of agricultural pollutants in water. The hybrid photocatalysts were prepared by an innovative method involving hydrothermal synthesis at 150 °C using a mechanochemically synthesized zeolitic imidazolate framework (ZIF-8) and titanium tetraisopropoxide as a titanium dioxide (TiO₂) precursor. Three composite photocatalysts with different mass fractions of titanium dioxide (5, 50, and 95 wt%) were synthesized and characterized, and their adsorption and photocatalytic properties investigated for the removal of imidacloprid. The equilibrium adsorption test showed that ZIF-8 is a good adsorbent and can adsorb 65% of the model component under the working conditions used in this work, while the hybrid photocatalysts can adsorb 1–3% of the model component. It is assumed that the adsorption is hindered by the TiO₂ layer on the surface of ZIF-8, which blocks the interactions of ZIF-8 and imidacloprid. A significant decrease in band gap energies (3.1–3.6 eV) was observed for the hybrid TiO₂/ZIF-8 photocatalysts compared to the values obtained with ZIF-8 (5 eV), depending on the mass fractions of TiO₂. The highest removal efficiency of imidacloprid was achieved with the hybrid photocatalysts containing 5 wt% TiO₂.

This study deals with the synthesis and characterization of a series of hybrid photocatalysts consisting of different loadings of TiO₂, Cd, and Fe on mesoporous SBA-15 material. The prepared samples were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), and tested for the removal of the neonicotinoid insecticide imidacloprid. The results showed that uncalcined 10% Cd-SBA-15 catalyst exhibited the best photocatalytic activity. The photocatalytic degradation of the imidacloprid was carried out in a batch photoreactor at different pH values, and in the presence or absence of additional compounds such as peroxymonosulfate (PMS) and peroxydisulfate (PDS). The best degradation results were achieved at a pH value of 6.5 with 10% Cd/SBA-15. The degradation performance increased with the addition of PMS and PDS. Based on the results of the experimental measurements, Cd/SBA-15 is a good candidate that can show a reasonable degradation efficiency and reactivity, especially in the presence of PDS or PMS.