Branislav Jović

Spectroscopic monitoring of photocatalytic degradation of the insecticide acetamiprid and its degradation product 6-chloronicotinic acid on TiO2 catalyst

Two spectroscopic methods, 1H NMR and FTIR, were developed for the monitoring of the photocatalytic degradation of acetamiprid, a widely used pyridine-based neonicotinoid insecticide, in UV-irradiated aqueous suspensions of O2/TiO2. The 1H NMR method allowed also the identification of the intermediates such as 6-chloronicotinic and formic acids, as well as separate monitoring of the kinetics of degradation of acyclic and aromatic moieties based on the different chemical shifts of the protons belonging to the methyl group of the acyclic and selected proton of the heterocyclic aromatic moiety. The FTIR procedure enabled the monitoring of the kinetics of degradation of the cyano group of the compound. The obtained results are in good agreement with the comparative HPLC-DAD and HPLC-MS/MS measurements, which also enabled the identification of certain intermediates. To get a deeper insight into the complex photocatalytic process, the photocatalytic degradation of 6-chloronicotinic acid, a stable degradation intermediate of acetamiprid, was also investigated by 1H NMR and HPLC-DAD methods. Based on the obtained data, a tentative reaction mechanism was proposed for the photocatalytic degradation of acetamiprid.

Adsorption of chlorinated phenols on multiwalled carbon nanotubes

This work studies the adsorption of four chlorinated phenols (2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,5-tetrachlorophenol and pentachlorophenol) in aqueous solutions on multiwalled carbon nanotubes (MWCNT). To investigate the influence of oxygen containing functional groups, adsorption parameters for the phenols were determined for original MWCNT (OMWCNT) and functionally modified MWCNT (FMWCNT) by acid treatment for 3 h and 6 h. The correlation between phenol adsorption affinity and specific surface area (SSA) indicates that OMWCNT have higher adsorption affinities for larger molecules such as tetrachlorophenol and pentachlorophenol, which suggests that mesopore filling is not the dominant mechanism controlling their adsorption. Electrostatic repulsion between disassociated chlorinated phenols and disassociated functional groups on the surface of both FMWCNT lead to adsorption decreasing with increasing functionalisation under neutral pH conditions. On OMWCNT, a positive correlation between molecular hydrophobicity and adsorption affinity was obtained, indicating hydrophobic interactions control the adsorption of chlorinated phenols. To investigate the role of π–π interactions, Kd values (at 0.01 and 0.5 SW) were normalized by hydrophobicity. The Kd/KOW values for all MWCNT decreased from 2,4-dichlorophenol to pentachlorophenol and were negatively correlated with the electron-acceptor property of the molecules. The most pronounced π–π interactions were observed for 2,6-dichlorophenol on all MWCNT.

FTIR investigation of solvent effects of N-methyl and N-tert-butyl benzamide

Infrared spectroscopy studies of N-methyl benzamide and N-tert-butyl benzamide in 12 organic solvents were undretaken to investigate solvent-solute interactions. The wavenumbers of carbonyl stretching vibration ν(C=O) in different solvents were correlated with the solvent acceptor number (AN), the linear solvation energy relationships (LSER), Catalan solvent parameters (SA, SB and SPP) and Buckingham equation. For both studied amides significant correlation of the position of the carbonyl band with empirical parameters was obtained. Based on obtained results it was assumed that the amide self-association and the steric effects are most important factors that determine position of carbonyl groups band in the IR spectra.

Empirical equation for preliminary assessment of soil texture

In this paper, for the first time type and texture of northern Serbian soils were examined using DRIFT spectroscopy. It was investigated whether it is possible to use the specular reflection of the quartz band for the purpose of the preliminary quantitative determination of texture properties. Investigation is conducted on the five most common soil types in Vojvodina: Arenosols, Fluvisols, Chernozems, Vertisols and Solonetz. Spectra were obtained using diffuse reflectance (DRIFT) technique in mid-IR. Spectral characteristics for five characteristic soil types in this region were determined. Certain regularities were observed regarding inorganic bands and main relations between these inorganic components and the texture parameters were determined. The empirical equation for the rough preliminary estimation of the soil texture was determined based on the absorbance values on the 2228 and 1211 cm-1.