Se⁴⁺ and N³⁻ ions were used as codopants to enhance the photocatalytic activity of TiO₂ under sunlight irradiation. The Se/N codoped photocatalysts were prepared through a simple wet-impregnation method followed by heat treatment using SeCl₄ and urea as the dopant sources. The prepared photocatalysts were well characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-diffuse reflectance spectroscopy (UV-DRS), scanning electron microscopy (SEM) and Raman spectroscopy. The codoped samples showed photoabsorption in the visible light range from 430 nm extending up to 580 nm. The photocatalytic activity of the Se/N codoped photocatalysts was evaluated by degradation of 4-nitrophenol (4-NP). The degradation of 4-NP was highly increased for the Se/N codoped samples compared to the undoped and single doped samples under both UV-A and sunlight irradiation. Aiming to determine the electronic structure and dopant locations, quantum chemical modeling of the undoped and Se/N codoped anatase clusters was performed using Density Functional Theory (DFT) calculations with the hybrid functional (B3LYP) and double-zeta (LanL2DZ) basis set. The results revealed that Se/N codoping of TiO₂ reduces the band gap due to mixing of N2p with O2p orbitals in the valence band and also introduces additional electronic states originating from Se3p orbitals in the band gap.

The presence of organophosphorus compounds (OPs) in the environmental counterparts has become an important problem because of their toxicity. In this study, the photocatalytic degradation reactions of the three OPs with hydroxyl radical were investigated by both experimental and quantum chemical methods. Photocatalytic degradation kinetics of the examined organophosphorus compounds were investigated under UV-A irradiation using TiO2 as the photocatalyst. The effects of the initial concentrations on the degradation rate have been examined. There was an observable loss of OPs in the presence of TiO2 photocatalyst under UV-A at 0.2 g TiO2 per 100 mL. The quantum chemical calculations have been carried out by the density functional theory (DFT) at B3LYP/6-31g(d) level. The reaction pathways were modelled to find the most probable mechanism for OPs with the OH radical and to determine the primary intermediates. The rate constants of the eight reaction paths were calculated by the transition state theory. Conductor-like polarizable continuum model (CPCM) was used as the solvation model with the intention of understanding the water effect. The theoretical results were in agreement with experimental ones.

Antibiotics that humans use are eliminated from the body with little change or no transformation at all. Eliminated antibiotic traces enter the receiving environment directly since they cannot be treated in prevalent wastewater treatment facilities. Microorganism resistance increase can be caused by low concentrations of antibiotic traces and high concentrations of traces of antibiotics can cause toxic effects. Thus, wastewaters containing traces of antibiotics have to be treated accordingly. Lincomycin is subsequently isolated from Streptomyces Lincolnensis. Lincomycin and its derivatives are antibiotics exhibiting biological activity against Gram-positive bacteria. Lyncomycin is a natural antibiotic found in environments as a pollutant due to its widespread use. This study aims to predict degradation mechanism of lyncomycin molecule in gaseous phase and aqueous media. The probable reaction path of lyncomycin molecule with OH radical was analyzed. The optimized geometry was calculated via Gauss View 5. Subsequently, the lowest energy status was found out through geometric optimization via Gaussian 09 program. With the aim to determine the intermediates occurring at the photocatalytic degredation mechanism of lyncomycin, geometric optimization of molecule was realized through Density Functional Theory (DFT) method. Activation energy for probable reaction path was calculated, and their most stable state from the thermodynamic perspective for the gaseous phase and aqueous media. The impact of water solvent was investigated by using conductor-like screening solvation model (COSMO) as the solvation model. The predicted mechanism was confirmed by comparison with the experimental results on simple structures reported in the literature.

In this study, the toxicological properties of some of the aromatic amine raw materials commonly used in textile dyes and the dyestuffs produced from these raw materials were examined with the OECD QSAR method and their toxicological effects on human health were investigated. In the literature review conducted with the relevant structures, it was seen that no study set was found in terms of toxicology, considering the comparison of raw materials and products. Studies have found that some aromatic amine raw materials and azo dyes produced from these raw materials are generally moderately irritating. While the related raw materials generally have eye irritant properties, the products do not have any irritating properties. It can be said that 12 aromatic amine raw materials and 13 azo dyes have skin sensitizing properties. The raw materials are 2,6-dibromo-4-nitro aniline, 6-methoxybenzothiazole-2-ylamine, 2-Bromo-4,6-dinotroaniline, and azo dyes, which are Disperse Brown 27-1, Disperse Brown 19 and Disperse Blue 291, are mutagenic.

The increasing use of dyes in various industries has raised concerns regarding the potential release of harmful substances into the environment and their influence on human health. The incorporating style of polyaniline-based catalysts has attracted great interest in the field of photocatalysis, specifically for dye degradation from water. Polyaniline CuO (PANI-CuO) catalysts with varying PANI/CuO mole ratios (1:8, 1:1, and 8:1) were synthesized by in-situ chemical oxidation polymerization (PCI) and mechano-chemical preparation (PCS) methods. FTIR, XRD, and SEM analyses confirmed the presence of CuO and PANI in PCS catalysts. However, CuO particles were not detected in PCI specimens due to the dissolution of CuO in a highly acidic medium. The photocatalytic efficiency of prepared two different series of PANI-CuO catalysts was assessed by the degradation of methylene blue (MB) dye degradation for comparative purposes. The results implied that the preparation process significantly concerns the photocatalytic performance with PCI catalysts exhibiting higher MB photocatalytic degradation than PCS specimens. The PCI-18 specimen achieved 56% degradation of MB in 300 minutes.