Kinetics of photocatalytic removal of 2-amino-5-chloropyridine from water

Titanium dioxide sensitized photocatalytic degradation of a pyridine pesticide analogue, 2-amino-5-chloropyridine, was investigated by monitoring the pyridine moiety degradation, as well as by monitoring the chloride generated in the process. Effect of the initial substrate concentration on the rate of its degradation is reported. Here we show that the kinetics of both reactions are of the zero-order in the entire investigated concentration range. The Langmuir-Hinshelwood kinetic model successfully described the influence of the initial substrate concentration on the rate of the pyridine moiety degradation. It was found that dechlorination of the substrate takes place by direct photolysis. The differences in the kinetics of pyridine moiety degradation and dechlorination were explained on the basis of the electrostatic potential for the investigated compound

Prisustvo zearalenona u najčešće uzgajanim sortama pšenice u Srbiji

A total of 45 samples of wheat from three different locations in Vojvodina were analyzed for the presence of zearalenone. Analytical methods based on clean-up by solid-phase extraction (SPE) columns and detection by liquid chromatography were used after validation. Limit of detection for ZEA in wheat was 18.6 μg/kg and the limit of quantification was 56.5 μg/kg. Recovery values ranged between 86% and 97%. The occurrence of ZEA in wheat was rather high with 53.3% of positive samples with the average value of 330 μg/kg. Incidences were found from 68 μg/kg to 1079 μg/kg. Contamination levels were above the established maximum limit for unprocessed cereals, other than maize, in as many as seventeen samples. These results were compared to the results of investigation of deoxynivalenol and fumonisin content, established in our previous work on the same samples. The results obtained were also compared to those of the neighboring countries where the relevant data existed and to the data of previous studies in our country.Na prisustvo zearalenona analizirano je ukupno 45 uzoraka pšenice sa tri različite lokacije u Vojvodini. Korišćene su analitičke metode zasnovane na prečišćavanju ekstrakcijom na čvrstoj fazi, te kvantifikacija tečnom hromatografijom, nakon validacije metode. Granica detekcije za zearalenon u pšenici je iznosila 18,6 μg/kg, a granica određivanja 56,5 μg/kg. Efikasnost metode je bila u opsegu od 86% do 97%. Zearalenon je bio prisutan u 53,3% ispitivanih uzoraka, sa prosečnim sadržajem od 330 μg/kg. Dobijene vrednosti sadržaja zearalenona su bile u opsegu od 68 μg/kg do 1079 μg/kg. U čak sedamnaest uzoraka je pronađena koncentracija ovog toksina koja prevazilazi maksimalni dozvoljeni sadržaj zearalenona u netretiranim žitaricama. Ovi rezultati su upoređeni sa vrednostima sadržaja deoksinivalenola i fumonizina u istim uzorcima dobijenim u našim prethodnim istraživanjima. Rezultati su takođe upoređeni sa dostupnim rezultatima dobijenim u našoj i susednim zemljama tokom prethodnih godina

Visible-light photocatalytic degradation of herbicide mecoprop in n-doped TiO2 suspensions

In this study, the nitrogen-doped TiO2 crystalline nanopowder was synthesized by calcination of the hydrolysis product of titanium tetraisopropoxide in ammonia. Obtained nanopowder was characterized by XRD and UV-Vis reflection techniques. The kinetics of visible-light (400-800 nm) photocatalytic degradation of herbicide mecoprop in N-doped TiO2 nanopowder aqueous suspensions was investigated and compared to results obtained for undoped TiO2.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Fumonisins and co-occurring mycotoxins in north Serbian corn

The presence of fumonisin has not been regulated in the legislation of the Republic of Serbia. Therefore, the data on contamination of cereals, especially corn, which is highly susceptible to contamination by this toxin, are not sufficient. This paper presents the results of testing the corn samples collected in the autumn 2009 on the territory of Bačka. Samples were analyzed for the contents of fumonisins and it was determined whether there is a correlation between the moisture content, total number and class of fungi, as well as the content of aflatoxin, ochratoxin and zearalenone. Using enzymatic immunoaffinity method it was discovered that the highest percentage of samples were contaminated with fumonisins, which was probably due to the presence of Fusarium molds as the most abundant ones. The positive samples contained fumonisin in the concentrations from 0.030 to 1.52 mg kg−1. The influence of the climate and moisture content of grain on fungal contamination and mycotoxin production was analyzed in order to investigate the predictability of the presence of mycotoxins

Prisustvo deoksinivalenola u uzorcima strnih žita u žetvenoj 2009/10. godini

Fusarium head blight (FHB) is present in all growing regions of small grains and causes significant losses in yield and grain quality. In our environmental conditions, dominant species is Fusarium graminearum Group 2. During 2009/10 there was a significant Fusarium infestation on wheat, barley and triticale. The aim of this study was to examine the contents of deoxynivalenol (DON) in cereal samples taken after 2009/10 harvest season. We analyzed 22 NS varieties of small grains from Rimski Šančevi, including 16 varieties of winter wheat, one facultative wheat variety, four varieties of winter barley and one variety of triticale. Analytical methods based on clean-up by solid-phase extraction (SPE) columns and detection by liquid chromatography were used. Fifteen out the 22 analyzed samples were positive for the presence of DON at a mean level of 0.537 mg/kg. The highest concentration was 1.952 mg/kg. These findings were in correlation with percentage of the Fusarium damaged kernels.Patogeni iz roda Fusarium su prisutni u svim rejonima gajenja strnih žita i nanose značajne gubitke u prinosu i kvalitetu zrna. Fuzariozu klasa pšenice prouzrokuje veći broj vrsta iz roda Fusarium. U našim uslovima gajenja dominantna je vrsta Fusarium graminearum Grupa 2. U toku 2009/10. godine došlo je do značajne pojave fuzarioza na pšenici, ječmu i tritikaleu. Cilj rada je bio da se ispita sadržaj DON-a na uzorcima strnih žita uzetih posle žetve iz uslova prirodne zaraze. Analizirane su 22 novosadske sorte strnih žita iz lokaliteta Rimski Šančevi, od čega: 16 sorti ozime pšenice, jedna fakultativna sorta pšenice, četiri sorte ozimog ječma i jedna sorta tritikalea. Uzorci su uzeti sa parcela različitih površina u zavisnosti od značaja i rasprostranjenosti gajene sorte. Analitičko određivanje je zasnovano na prečišćavanju sirovog ekstrakta analiziranih uzoraka pomoću tzv. Mucosep kolona, a zatim je sadržaj DON-a kvantitativno određen tečnom hromatografijom. Od 22 analizirana uzorka strnih žita čak 15 (68,2%) je bilo pozitivno na prisustvo DON-a. Još veći procenat zaraženosti DON-om je utvrđen kada je u pitanju samo pšenica (82,4%). Prosečan sadržaj DON-a je iznosio 0,537 mg/kg a najveća koncentracija je utvrđena u uzorku tritikalea i iznosila je visokih 1,952 mg/kg. Od svih uzoraka koji su bili pozitivni na prisustvo ovog mikotoksina, 2 su prevazilazila koncentracije koje su propisane od strane Evropske komisije. Sve ovo ukazuje na visoku zaraženost strnih žita sa naših polja iz žetve 2010. Procenat fuzarioznih zrna kod 16 ispitivanih sorti pšenice kretao se od 1 do 11,5%, a gubici u masi 1000 zrna od 1,2 do 5,7%. Između jačine zaraze u polju i sadržaja mikotoksina DON ustanovljena je potpuna pozitivna korelacija kod pojedinih sorti. Fakultativna sorta pšenice Nataša je imala visoku koncentraciju DON od 1,572 mg/kg, pri stepenu zaraze u polju od 33,3% zaraženih klasova po 1 m2. Sorta Zvezdana imala je najniži procenat zaraze u polju od 1% i kod nje nije determinisano prisustvo mikotoksina DON

Photocatalytic activity of TiO2 nanoparticles modified with dopamine

Photocatalytic activity of bare colloidal TiO2 nanoparticles (NPs, d~45Å) and surface modified with dopamine was obtained following degradation reaction of herbicide RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP, C10H11ClO3) under UV light irradiation. Results indicated that inner sphere charge transfer (CT) complex is formed on the surface of TiO2 NPs due to modification with dopamine which induced decreasing of the photocatalytic efficacy of TiO2 NPs

Potential of TiO2 with various au nanoparticles for catalyzing mesotrione removal from wastewaters under sunlight

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+ >•OHads >•OHbulk. Finally, several intermediates that were formed during the photocatalytic treatment of mesotrione were identified. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Synthesis and Characterization of Rutile TiO2Nanopowders Doped with Iron Ions

Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5–7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence

Expert system for determination of fumonisins in corn samples

An expert system (ES) to solve the problem of choosing an optimal procedure for the determination of fumonisins in corn samples was developed, having in mind that these toxins most frequently contaminate this particular cereal. In constructing the ES use was made of the deterministic approach starting from the assumption that the experts in the field have a profound knowledge about the problem in question. The ES knowledge base contains the solutions that have been published in the pertinent literature, as well as some solutions and recommendations, which we have developed and introduced. On the basis of this information, as well as on the basis of the demanded method detection limit, available equipment, chemicals, as well as the time the experimenter has at his disposal for the determination, the ES proposes a procedure for solving the given analytical problem, starting from sampling, preparation of all the necessary solutions, the appropriate apparatus, probe preparation, the mode of determining results, calculation of the results, and provides a survey of all the relevant literature references. The base of ES is a shell, which can work under a variety of Microsoft Windows operating systems. In the development of ES and its adaptation for users who are not familiar with computer techniques, different tools, which operate with Microsoft Windows operating systems, as well as the tools within Microsoft Office are used