Optimizacija uslova za degradaciju pesticida pomocu hlor dioksida

The аim of this study was to find optimal conditions for degradation of pesticides, such as pethoxamid and metazachlor with chlorine dioxide in deionized water.Cilj ovog rada је bio da se pronadju optimalni uslovi za degradaciju pesticida, kao sto su: petoksamid i metazahlor роmоću hlor dioksida u dejonizovanoj vodi

Degradation of triazine group herbicides by chlorine dioxide

This study investigates degradation of triazine group herbicides (atrazine, terbuthylazine and prometryn) with chlorine dioxide in deionized water and in real water system (water from river Sava) under optimal conditions

Poli(uretan-siloksani) na bazi hiperrazgranatog poliestra kao umreživača - sinteza i karakterizacija

A series of novel polyurethane crosslinked structures (PUs) was prepared from α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO), 4,4'-methylenediphenyl diisocyanate and Boltorn ® hyperbranched polyester of the third pseudo generation. The hydroxyfunctional hyperbranched aliphatic polyester with 26 end groups was used as a crosslinking agent. In order to improve the compatibility of all the reactants during the synthesis, the PU samples were prepared by two-stage, step-growth polymerization in solution. The content of the soft EO-PDMS-EO segments was varied in the range from 15 to 40 wt. %. The influence of the EO-PDMS-EO content on the swelling behavior, crosslink density, hardness, and the thermal and surface properties of the synthesized PUs was investigated. The structure of the synthesized polyurethanes was confirmed by the presence of specific bands in the Fourier transform infrared spectra. Swelling studies were performed to determine the crosslink density and polyurethane networks with lower EO-PDMS-EO contents had higher crosslink densities. The glass transition temperature of the synthesized PUs, determined by differential scanning calorimetry, slightly increased from 50 to 58°C on decreasing the EO-PDMS-EO content because of the higher crosslink density of the samples. Increasing the EO-PDMS-EO content led to better thermal stability, as was evidenced by the onset temperature of weight loss. The surface of the polyurethane networks became more hydrophobic with increasing EO-PDMS-EO content. The surface morphology of synthesized polyurethanes was analyzed by scanning electron microscopy.U ovom radu prikazana je sinteza, struktura i neka svojstva novih umreženih poliuretana pripremljenih polazeći od α,ω-dihidroksi-(etilenoksid-poli(dimetilsiloksan)-etilenoksid) pretpolimera (EO-PDMS-EO), 4,4'-metilendifenildiizocijanata i Boltorn® hiperrazgranatog poliestra treće pseudo-generacije. Hiperrazgranati hidroksi funkcionalni alifatski poliestar sa 26 krajnjih grupa služio je kao umrežavajući agens pri sintezi poliuretana. U cilju poboljšanja kompatibilnosti reaktanata tokom sinteze, poliuretani su sintetisani dvostepenom polimerizacijom u rastvoru. Sadržaj mekog EO-PDMS-EO segmenta variran je u opsegu od 15 do 40 mas. %. Ispitan je uticaj EO-PDMS-EO sadržaja na ponašanje pri bubrenju, gustinu umrežavanja, tvrdoću, termička i površinska svojstva sintetisanih poliuretana. Struktura sintetisanih poliuretana potvrđena je FTIR spektroskopijom. Ponašanje pri bubrenju je ispitivano kako bi se odredila gustina umrežavanja i pokazano je da poliuretanske mreže sa nižim EO-PDMS-EO sadržajem imaju veću gustinu umrežavanja. Rezultati diferencijalne skenirajuće kalorimetrije pokazali su povećanje temperature ostakljivanja poliuretana od 50 do 58°C sa smanjenjem EO-PDMS-EO sadržaja kao posledicu veće gustine umreženosti uzoraka. Sintetisani poliuretani sa većim sadržajem EO-PDMS-EO segmenata pokazuju bolju termičku stabilnost, što je potvrđeno porastom početne temperature degradacije, određene TG analizom. Hidrofobnost površine poliuretana je rasla sa povećanjem sadržaja EO-PDMS-EO u odgovarajućem uzorku. Površinska morfologija sintetisanih poliuretana je analizirana skenirajućom elektronskom mikroskopijom

Degradation herbicides with chlorine dioxide: degradation efficiency and toxicity test

The main objective of this study was to find optimal parameters for degradation of herbicides, such as nicosulfuron and thifensulfuron-methyl, with chlorine dioxide in deionized water. In order to examine the optimal parameters, degradation of herbicides was investigated under light or dark conditions with different amount of chlorine dioxide (5 and 10 ppm), different time of degradation (30 min, 1, 2, 3, 6 and 24 h) and at different pH values (3, 7 and 9). Degradation efficiency of herbicides was monitored using HPLC-DAD. Acute toxicity tests were performed for degradation products after the treatment with chlorine dioxide

Supplementary material for the article: Pergal, M. V.; Kodranov, I. D.; Pergal, M. M.; Dojčinović, B. P.; Stanković, D. M.; Petković, B. B.; Manojlović, D. D. Assessment of Degradation of Sulfonylurea Herbicides in Water by Chlorine Dioxide. Water, Air, and Soil Pollution 2018, 229 (9). https://doi.org/10.1007/s11270-018-3947-2

Supplementary material for: [https://doi.org/10.1007/s11270-018-3947-2]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2203

Proučavanje morfologije i termomehaničkih svojstava umreženih poli(uretan-siloksana) na bazi hiperrazgranatog poliestra

Two series of polyurethane films based on hyperbranched polyester of the second pseudo-generation (Boltorn®), 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide)(EO-PDMS-EO) and α,ω-dihydroxypropyl-poly(dimethylsiloxane) (HP-PDMS), were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomechanical and surface properties of the synthesized polyurethanes was studied by atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA) and water absorption measurements. It was found that these techniques confirmed existence of microphase separated morphology. Synthesized polyurethanes exhibited two glass transition temperatures and one second relaxation process. The results showed that polyurethanes based on HP-PDMS had higher surface roughness, better microphase separation and waterproof performances. Samples synthesized with lower PDMS content had less hydrophobic surface, but higher crosslinking density and better thermomechanical properties.U ovom radu pripremane su dve serije poliuretanskih filmova na bazi hiperrazgranatog poliestra druge pseudo generacije (Boltron), 4,4¢-metilendifenildiizocijanata i dva različita iloksanska pretpolimera kao što su a, ω-dihidroksi- (etilenoksid-poli(dimetilsiloksan)-etilenoksid)(EO-PDMS-EO) i a,ω-dihidroksipro-pilpoli(dimetilsiloksan)(HP-PDMS), dvostepenom polimerizacijom u rastvoru. Uticaj vrste i sadržaja mekog segmenta na morfologiju, termomehanička i površinska svojstva sintetisanih poliuretana je proučavan pomoću mikroskopije atomske sila (AFM), rasipanja X-zraka pod malim uglovima (SAXS), skenirajuće elektronske mikroskopije (SEM), dinamičko mehaničke termičke analize (DMTA) i merenja količine apsorbovane vode. Nađeno je da primenjene tehnike potvrđuju postojanje morfologije mikrofaznog razdvajanja. Sintetisani poliuretani pokazivali su dve temperature ostakljivanja i jedan sekundarni relaksacioni proces. Rezultati su pokazali da poliuretani na bazi HP-PDMS su imali veći koeficijent hrapavosti, bolje mikrofazno razdvajanje i bolju otpornost prema vodi. Uzorci sintetisani sa nižim sadržajem PDMS-a su imali manju hidrofobnost, ali veću gustinu umrežavanja i bolja termomehanička svojstva

Novel crosslinked polyurethanes based on hyperbranched polyester

The polyurethane (PU) elastomers based on hydroxy-terminated hyperbranched polyester (BH-20) and 4,4′-methylenediphenyl diisocyanate (MDI) as hard segments and hydroxyl-terminated ethylene oxide-poly(dimethylsiloxane)- ethylene oxide (PDMS-EO) as soft segment, were synthesized and examined in this work. The obtained results show that sol fraction decreases and thermal stability increases with increase of the hard segment content

Supplementary material for the article: Pergal, M. V.; Kodranov, I. D.; Pergal, M. M.; Dojčinović, B. P.; Stanković, D. M.; Petković, B. B.; Manojlović, D. D. Assessment of Degradation of Sulfonylurea Herbicides in Water by Chlorine Dioxide. Water, Air, and Soil Pollution 2018, 229 (9). https://doi.org/10.1007/s11270-018-3947-2

Supplementary material for: [https://doi.org/10.1007/s11270-018-3947-2]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2203

Polycyclic aromatic hydrocarbons in two sedimentary environments of the Tertiary Krepoljin coal basin

In the present study, statistical correlation analysis and multivariate statistical techniques (PCA/FA) were employed to investigate polycyclic aromatic hydrocarbons (PAHs) in sediments, such as illite-montmorillonite (IM) and calcite (Ct), from two sedimentary environments of the Tertiary Krepoljin brown coal basin in Serbia. The coal and sediment layers were formed in fresh-water bogs during the Lower Miocene period. The total amount of extractable PAHs was determined by gas chromatography with a triple quad mass detector (GC-MS-MS), and it ranged from 449 to 10585 μg l−1 in all sediments. Eight of the total 16 PAHs, which ranged from 175.17 to 658.42 μg l−1, include benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-cd]pyrene, which are regarded as potentially carcinogenic, indicating a higher possibility of adverse ecological effects. Medium molecular-weight (MMW) PAHs were found to be predominant in all sediments. PAH concentrations are affected by several factors, such as carbon content, H/C mole ratio, and (less significant) O/C mole ratio. The non-existence of a correlation between the N/C ratio and other parameters indicates unspecific changes which accompany the original organic matter. The lower-sulfur Ct sediment samples were found to have a higher PAH content than higher sulfur IM samples, leading to the conclusion that the PAH content of sediments may be related to the depositional environment

Influence of coal combustion temperature on polycyclic aromatic hydrocarbons formation in coal fired power plants and its consequences on the environment

Naučni cilj istraživanja obuhvaćenog ovom doktorskom disertacijom je ispitivanje i utvrđivanje mehanizama formiranja policikličnih aromatičnih ugljovodonika (PAH) in situ, tokom sagorevanja uglja i promene temperature sagorevanja u termoelektrani „Nikola Tesla B“, kao i istraživanje njihove sudbine (razlaganja i degradacije) u proizvodima sagorevanja tokom transporta i nakon odlaganja na deponiju pepela i šljake. Količine policikličnih aromatičnih ugljovodonika su ispitivane u uglju koji se koristi u termoelektrani, proizvodima nastalim sagorevanjem uglja pri različitim temperaturama (različitim tipovima pepela i šljake), kao i u deponijskom pepelu i šljaci sa aktivne, trenutno korišćene, i pasivne, ranije korišćene kasete deponije. Ekstrakcija PAH-ova iz čvrstih uzoraka je rađena pomoću ultrazvuka u odgovarajućem rastvaraču, dok je analiza pripremljenih uzoraka izvedena pomoću gasnog hromatografa povezanog sa masenim detektorom. Ispitivana je i ekstraktibilnost PAH-ova iz elektrofilterskog pepela u uslovima koji oponašaju one koji mogu biti prisutni u životnoj sredini. Ekstrakcija PAH-ova iz pripremljenih tečnih uzoraka vršena je rastvaračem u levku za odvajanje, dok je analiza pripremljenih uzoraka izvođena pomoću gasnog hromatografa povezanog sa masenim detektorom. Zaključeno je da sa porastom temperature sagorevanja lignita u termoelektrani Nikola Tesla B, ukupna količina PAH-ova u proizvodima sagorevanja raste u temperaturnom opsegu od 930 do 973,5 oC, dok sa daljim povećanjem temperature ukupna količina ostaje konstantna. PAH-ovi u pepelu i šljaci se ponašaju različito: količine PAH-ova rastu u pepelu zbog njihove sinteze tokom sagorevanja u ložištu i zbog njihovog povećanog isparavanja usled povećanih...The scientific aim of the research covered by this dissertation is to examine and determine the mechanisms of formation of polycyclic aromatic hydrocarbons in situ during the combustion of coal and variation of temperature combustion in thermal power plant "Nikola Tesla B", as well as the study of their fate (decomposition and degradation) in the products of combustion during the transport and after deposition of ash and slag. The concentrations of polycyclic aromatic hydrocarbons were tested in coal used in thermal power plant, coal combustion products formed by the combustion of coal at different temperatures (various types of fly ash and slag), as well as ash and slag from active, currently used, and passive, previously used cassette of ash dump. Extraction of PAH’s from solid samples was carried out by means of ultrasound in a suitable solvent, while the analysis of the prepared samples was performed using gas chromatography with mass detector. The extractability of PAHs in fly ash in conditions that mimic those that may be present in the environment was investigated. Extraction of PAHs from the prepared liquid samples was carried out using solvent in a separating funnel, while the analysis of the prepared samples was performed by gas chromatography with mass detector. It is concluded that with increasing of combustion temperature of lignite in the thermal power plant Nikola Tesla B, the total amount of PAHs in the products of combustion increases from 930 to 973.5 °C, and with a further increase in temperature total amount becomes constant. PAHs in ash and slag behave differently: the quantities of PAHs are increasing in ash because of their synthesis during combustion in the furnace and because of their increased evaporation due to increased temperature, resulting in, among other things, the presence of PAHs..