Pharmaceuticals and pesticides are emerging contaminants problematic in the aquatic environment because of their adverse effects on aquatic life and humans. In order to remove them from water, photocatalysis is one of the most modern technologies to be used. First, newly synthesized photocatalysts were successfully prepared using a sol–gel method and characterized by different techniques (XRD, FTIR, UV/Vis, BET and SEM/EDX). The photocatalytic properties of TiO₂, ZnO and MgO nanoparticles were examined according to their removal from water for two antibiotics (ciprofloxacin and ceftriaxone) and two herbicides (tembotrione and fluroxypyr) exposed to UV/simulated sunlight (SS). TiO₂ proved to be the most efficient nanopowder under UV and SS. Addition of (NH₄)₂S₂O₈ led to the faster removal of both antibiotics and herbicide fluroxypyr. The main intermediates were separated and identified for the herbicides and antibiotic ciprofloxacin. Finally, the toxicity of each emerging pollutant mixture and formed intermediates was assessed on wheat germination and biomass production.

This work is focused on the kinetics, mineralization, and toxicological assessments of the antidepressant drug amitriptyline hydrochloride (AMI) in UV or solar illuminated aqueous suspensions of ZnO, TiO₂ Degussa P25, and TiO₂ Hombikat. ZnO was proven to be the most effective photocatalyst, and it was used for all further experiments under solar irradiation. The highest reaction rate was observed at 1.0 mg/mL of catalyst loading. In the investigated initial concentration range (0.0075–0.3000 mmol/L), the degradation rate of AMI increased with the increase of initial concentration in the investigated range. The effects of H₂O₂, (NH₄)₂S₂O₈, and KBrO₃, acting as electron acceptors, along with molecular oxygen were also studied. By studying the effects of ethanol and NaI as a hydroxyl radical and hole scavenger, respectively, it was shown that the heterogeneous catalysis takes place mainly via free hydroxyl radicals. In the mineralization study, AMI photocatalytic degradation resulted in ~30% of total organic carbon (TOC) decrease after 240 min of irradiation; acetate and formate were produced as the organic intermediates; NH₄⁺, NO₃⁻, NO₂⁻ ions were detected as nitrogen byproducts. Toxicity assessment using different mammalian cell lines, showed that H-4-II-E was the most sensitive one.

Nowadays, great focus is given to the contamination of surface and groundwater because of the extensive usage of pesticides in agriculture. The improvements of commercial catalyst TiO₂ activity using different Au nanoparticles were investigated for mesotrione photocatalytic degradation under simulated sunlight. The selected system was 2.43 × 10⁻³% Au–S–CH₂–CH₂–OH/TiO₂ (0.5 g/L) that was studied by transmission electron microscopy and ultraviolet-visible (UV-Vis) spectroscopy. It was found that TiO₂ particles size was ~20 nm and ~50 nm, respectively. The Au nanoparticles were below 10 nm and were well distributed within the framework of TiO₂. For 2.43 × 10⁻³% Au–S–CH₂–CH₂–OH/TiO₂ (0.5 g/L), band gap energy was 2.45 eV. In comparison to the pure TiO₂, addition of Au nanoparticles generally enhanced photocatalytic removal of mesotrione. By examining the degree of mineralization, it was found that 2.43 × 10⁻³% Au–S–CH₂–CH₂–OH/TiO₂ (0.5 g/L) system was the most efficient for the removal of the mesotrione and intermediates. The effect of tert-butanol, NaF and ethylenediaminetetraacetic acid disodium salt on the transformation rate suggested that the relative contribution of various reactive species changed in following order: h⁺ > ^●OH_ads > ^●OH_bulk. Finally, several intermediates that were formed during the photocatalytic treatment of mesotrione were identified.

Fractional multivariate design of experiments with seven factors was used to chemometrically evaluate adsorption of tembotrione on the surface of catalyst, efficiency of photocatalytic degradation of tembotrione, and removal efficiency. For adsorption, the experiments revealed two significant main effects (loading of TiO₂ and concentration of KBrO₃) and two interactions (loading of TiO₂ × purging of O₂ and loading of TiO₂ × stirring during and 5 min before irradiation). Model for efficiency of photocatalytic degradation of tembotrione revealed three significant main effects (concentration of KBrO₃, purging of O₂, and stirring during and 5 min before irradiation), while overall removal efficiency had four significant main effects (concentration of KBrO₃, purging of O₂, loading of TiO₂, and stirring during and 5 min before irradiation) and one two factor interaction (loading of TiO₂ × concentration of KBrO₃). The optimal removal yield of tembotrione was 99.5% with TiO₂ loading of 1.25 mg/ml, KBrO₃ concentration of 4.33 mM, β‐cyclodextrin with Au in the ratio 2:1, 3 ml/min O₂ purging, and stirring before and during irradiation. The effect of tert‐butanol, NaF, EDTA × 2Na, and p‐benzoquinone on the tembotrione removal under optimal experimental conditions suggested that the relative contribution of various reactive species changed in following order: ˃ ^●OH_ads ˃ h⁺ ˃ ^●OH_free.