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Synthesis and structural characterization of novel conjugates of N-substituted benzimidazoles
No full textU okviru ovog rada provedena je sinteza i strukturna karakterizacija novih konjugata N-supstituiranih benzimidazola. Ciljani amidino supstituirani benzamidi priređeni su uobičajenim metodama organske sinteze i mikrovalovima potpomognutom sintezom. U prvom sintetskom koraku 4-N supstituirani 3-nitrobenzonitrili 2 i 3 priređeni su mikrovalovima potpomognutom aminacijom 4-klor-3-nitrobenzonitrila 1 uz korištenje odgovarajućeg amina. U drugom koraku spojevi 2 i 3 reducirani su u diamino supstituirane benzonitrile 4 i 5 korištenjem SnCl2 x 2H2O. 2-aminobenzimidazoli 6 i 7 priređeni su ciklokondenzacijom spojeva 4 i 5 korištenjem BrCN-a. U zadnjem koraku sinteze priređeni su 2-benzimidazolil supstituirani benzamidi 10, 11 i 12 kondenzacijom spojeva 6 i 7 s odgovarajućim karboksilnim kiselinama 8 i 9. Ciljani amidino supstituirani spojevi 13 i 14 sintetizirani su Pinnerovom reakcijom u kiselom mediju iz odgovarajućeg cijano supstituiranog spoja 10. Strukture priređenih spojeva potvrđene su 1H i 13C NMR spektroskopijom, a tijek Pinnerove reakcije praćen je IR spektroskopijom.This work presents the synthesis and structural characterization of novel conjugates of N-substituted benzimidazoles. Targeted amidino substituted benzamides were prepared by usual methods of organic chemistry and by microwave-assisted reactions. In first step of synthesis, 4-N substituted 3-nitrobenzonitriles 2 and 3 were prepared by microwave-assisted amination of 4-chloro-3-nitrobenzonitrile 1 using the corresponding amines. In second step, compounds 2 and 3 were reduced to diamino-substituted benzonitriles 4 and 5 using
SnCl2 x 2H2O. 2-aminobenzimidazoles 6 and 7 were prepared by cyclocondensation of compounds 4 and 5 with BrCN. In the last step of synthesis, 2-benzimidazolyl-substituted benzamides 10, 11, and 12 were prepared by condensation of compounds 6 and 7 with the corresponding carboxylic acids 8 and 9. Targeted amidino substituted compounds 13 and 14 were synthesized by Pinner reaction in acidic medium from corresponding cyano substituted 10. Structures of prepared compounds were confirmed with 1H i 13C NMR spectroscopy, while Pinner recation was monitored by IR spectroscopy
Methods of digestion, isolation and identification of microplastics present in the fish gut content
No full textPlastika je postala sveprisutan materijal u vodenim ekosustavima. Masovna proizvodnja dovela je i do masovnog nastajanja plastičnog otpada koji raznim procesima u prirodi postaje mikroplastični (MP) otpad te nerijetko završi upravo u vodenim staništima. Zbog dokazanih toksičnih učinaka na živi svijet MP se smatra globalnom onečišćujućom tvari u slatkovodnim i morskim ekosustavima, osobito zbog mogućnosti transporta kroz trofičke razine sve do čovjeka. Ribe su u vodi konstantno izložene riziku unosa i akumulacije MP čestica u njihov organizam. Mogu poslužiti kao dobri bioindikatori, a dosadašnja istraživanja ukazuju na visoku stopu pronalaska čestica MP-a u probavnom sustavu riba. Razvijanje metoda za izolaciju i točno kvantificiranje MP-a u morskim i slatkovodnim staništima sve je važnije. Za praćenje prostorne distribucije i vremenskih trendova morskog MP otpada, izrazito je važno razviti i implementirati standardizirane protokole, kako bi se učinkovito i točno odredila količina MP-a u različitim staništima. U ovome radu ispitivao se utjecaj razgradnje primjenom četiri različite metode na izolaciju i određivanje MP čestica iz probavila riba iz slatkovodnih i morskih ekosustava Republike Hrvatske. Dobiveni rezultati ukazuju da je kombinacija dušične kiseline, HNO3 i fluorovodične kiseline, HF najprikladnija metoda za izolaciju MP iz probavila riba, s minimalnim utjecajem na njezinu strukturu. U sadržaju probavila svih analiziranih jedinki riba identificirane su MP čestice, čime smo potvrdili njezinu prisutnost i unos u organizme vodenih ekosustava.Plastic has become a ubiquitous material in aquatic ecosystems. Its mass production has also led to the mass formation of plastic waste, which through various processes in nature becomes microplastic (MP) waste and often ends up in aquatic habitats. Due to its proven toxic effects on living things, MP is considered a global contaminant in freshwater and marine ecosystems, especially regarding the possible transportation through trophic levels, all the way to humans. In water, fish are constantly exposed to the risk of ingestion and accumulation of MP particles in their organism. They can serve as good bioindicators, and previous research indicates a high rate of finding MP particles in the digestive system of fish. Development of methods for isolation and accurate quantification of MP in marine and freshwater habitats is increasingly important. For monitoring of the spatial distribution and temporal trends of marine MP debris, development and implementation of standardized protocols is highly important, in order to efficiently and accurately determine the quantity of MP in different habitats. In this work, the influence of digestion by four different methodologies on isolation and determination of MP particles from the intestine of fish from freshwater and marine ecosystems of the Republic of Croatia were examined. The obtained results indicate that combination of nitric acid, HNO3, and hydrofluoric acid, HF represents the most appropriate methodology for MT isolation from fish intestine, with minimum influence on its structure. The particles of MP were identified in the gut content of all analysed fish, therefore confirming its presence and uptake in aquatic organisms
Preparation of polycaprolactone composites
No full textNedostatno i loše zbrinjavanje polimernog otpada dovodi do sve većeg zagađenja planeta Zemlje i rastućih ekoloških problema. Uobičajeno korištenje materijala koji se dobivaju iz nafte kao polazne neobnovljive sirovine, prepoznato je kao značajan doprinos tom rastućem problemu, što je potaklo znanstvenike da se sve više okreću istraživanjima o uporabi biorazgradivih polimera. Biorazgradivi materijali razgrađuju se u okolišu djelovanjem mikroorganizama i utjecajem atmosferalija. Imaju pozitivni utjecaj na okoliš, a često su jeftiniji od materijala dobivenih preradom naftnih derivata. U ovom radu analizirane su polimerne mješavine termoplastičnog škroba (TPS) i polikaprolaktona (PCl) te njihovi kompoziti uz dodatak TiO2. Karakterizacija polimernih mješavina i kompozita s TiO2 provedena je pomoću diferencijalne pretražne kalorimetrije (DSC), termogravimetrijske analize (TGA) te analizom mehaničkih svojstava. Rezultati ukazuju na bolja svojstva kompozita u odnosu na polimerne mješavine. Nekolicinu kompozita i polimernih mješavina, konkretno za omjere PCl/TPS 90/10 i 80/20, moguće iskoristiti kao zamjenu za čisti PCl što mu smanjuje cijenu, a povećava biorazgradivost.Inadequate and poor disposal of polymer waste leads to increasing pollution of the planet Earth and growing environmental problems. The usual use of materials obtained from oil as starting non-renewable raw materials is recognized as a significant contribution to this growing problem, which has encouraged scientists to increasingly turn to research on the use of biodegradable polymers. Biodegradable materials are broken down in the environment by the action of microorganisms and the influence of atmospheric agents.
They have a positive impact on the environment, and are often cheaper than materials obtained from the processing of petroleum products. In this work, polymer mixtures of thermoplastic starch (TPS) and polycaprolactone (PCl) and their composites with the addition of TiO2 were analyzed. Characterization of polymer mixtures and composites with TiO2 was carried out using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and analysis of mechanical properties. The results indicate better properties of composites compared to polymer mixtures. Several composites and polymer mixtures, specifically for
PCl/TPS ratios 90/10 and 80/20, can be used as a substitute for pure PCl, which reduces its price and increases biodegradability
Determination of insulation materials properties
No full textCilj ovog rada je ispitati uporabna svojstva izolacijskih materijala od kamene vune. U eksperimentalnom dijelu mjerena su sljedeća mehanička svojstva: tlačna čvrstoća (engl. compression strength - CS), delaminacijska čvrstoća (engl. delamination strength - DS) i točkasto opterećenje (engl. point load - PL). Uz nabrojana mehanička svojstva, mjerila se i toplinska provodljivost izolacijskih proizvoda. Eksperimentalni dio rada izrađen je u sklopu obavljanja stručne prakse u tvornici Rockwool Adriatic d. o. o. Za potrebe diplomskog rada, testirana su i uspoređena četiri proizvoda kamene vune od kojih se tri koriste za kontaktne fasade (Frontrock Max Plus, Frontrock Max E i Frontrock Extra) dok se četvrti proizvod, Hardrock Energy Plus koristi za izolaciju ravnih i kosih krovova.The aim of this paper is to examine the performance properties of stone wool insulation materials. In the experimental part, the following mechanical properties were measured: compression strength (CS), delamination strength (DS) and point load (PL). In addition to the listed mechanical properties, the thermal conductivity of the insulating products was also measured. The experimental part of the work was done as part of the professional practice at the Rockwool Adriatic d.o.o. factory. For the purposes of the thesis, four stone wool products were tested and compared, three of which are used for contact facades (Frontrock Max Plus, Frontrock Max E and Frontrock Extra), while the fourth product, Hardrock Energy Plus, is used to insulate flat and pitched roofs
Wastewater as indicators of consumption of illegal substances
No full textU radu je dan pregled metoda analize otpadnih voda u svrhu procjene potrošnje ilegalnih supstanci. Metoda, poznata kao epidemiologija temeljena na otpadnim vodama (WBE), omogućuje procjenu količine konzumiranih ilegalnih supstanci u zajednici putem analize metabolita prisutnih u otpadnim vodama. Metoda analize otpadnih voda u svrhu mjerenja količine ilegalnih supstanci obuhvaća uzorkovanje sirove otpadne vode iz različitih gradova svijeta i uporabu naprednih analitičkih tehnika, poput tekućinske kromatografije sa spektrometrijom masa i ekstrakcije na čvrstoj fazi, za identifikaciju i kvantifikaciju ilegalnih supstanci. U radu su prikazani nedostatci, prednosti i prijedlozi za preciznije provođenje analize otpadnih voda. Metoda analize otpadnih voda nudi objektivan i nepristran način prikupljanja podataka, što je ključno za praćenje promjena u novim obrascima potrošnje.The paper provides an overview of methods for wastewater analysis aimed at assessing the consumption of illegal substances. The method, known as wastewater-based epidemiology (WBE), enables the estimation of the amount of illegal substances consumed in a community through the analysis of metabolites present in wastewater. The wastewater analysis method for measuring the amount of illegal substances includes sampling raw wastewater from various cities worldwide and using advanced analytical techniques, such as liquid chromatography-mass spectrometry and solid-phase extraction, to identify and quantify illegal substances. The paper presents the disadvantages, advantages, and suggestions for more precise implementation of wastewater analysis. The wastewater analysis method offers an objective and unbiased way of collecting data, which is crucial for monitoring changes in new consumption patterns
Equilibrium-based methods of multicomponent absorption, stripping, distillation and extraction modelling
No full textRavnotežne metode proračuna procesa destilacije, ekstrakcije, apsorpcije i desorpcije temelje se na rješavanju MESH jednadžbi pomoću različitih metoda. Temeljne metode rješavanja jednadžbi su metoda točke vrenja, metoda sumiranja protoka, Newton-Raphsonova i „insideout“ metoda. Posljednje dvije metode se najviše koriste za izračune s obzirom na to da su najrazvijenije te su primjenjivije za rješavanje većeg broja kompleksnijih problema, dok su prve dvije metode najčešće u inicijalizacijskoj fazi ovih metoda. [1,2,3]Equilibrium methods for calculating distillation, extraction, absorption, and stripping processes rely on solving the MESH equations through various techniques. Fundamental methods include the bubble-point method, the sum-rates method, the Newton-Raphson method, and the "insideout" method. While the latter two methods are preferred for their advanced capabilities in solving complex problems, the first two methods are typically employed for their initialization. [1,2,3
Liquid-liquid equilibrium in the systems based on fatty acid butyl ester synthesized from sunflower, rapeseed and coconut oil
No full textZadatak ovog rada je eksperimentalno odrediti ravnotežu kapljevina-kapljevina u dvokomponentnim i pseudotrokomponentnim sustavima s butilnim esterima masnih kiselina (eng. fatty acid butyl ester, FABE) sintetiziranih iz suncokretovog, kokosovog i repičinog ulja u svrhu ispitivanja utjecanja sastava biodizela na fazno ponašanje. U sustavima glicerol – voda – FABE, butanol – voda – FABE i voda – glicerol – FABE eksperimentalno je određeno fazno ponašanje koje je prikazano u trokutnim dijagramima odgovarajućim binodalnim krivuljama, ravnotežnim sastavima i veznim linijama. Ravnoteža je određena pri 25 °C i atmosferskom tlaku. Također su izmjerena fizikalno-kemijska svojstva biodizela, viskoznost, gustoća, površinska napetost i tecište. Uz navedena mjerenja, biodizel je ispitan i diferencijalnom pretražnom kalorimetrijom (eng. differential scanning calorimetry, DSC), te termogravimetrijom (eng. thermogravimetry, TGA). Metodom plinske kromatografije ispitan je sastav biodizela te prisutnost nečistoća i neizreagiranih reaktanata reakcije sinteze. Utvrđena je potpuna mješljivost u dvokomponentnim sustavima voda – glicerol i glicerol – butanol te djelomična mješljivost u sustavu voda – butanol. Također je potvrđena potpuna nemješljivost biodizela s vodom i glicerolom. Sastav biodizela nema utjecaj na fazno ponašanje, već samo na fizikalna svojstva biodizela.The main goal of this work was experimental determination of the liquid-liquid equilibrium in binary and pseudo ternary systems with fatty acid butyl esters (FABE) synthesized from sunflower, coconut and rapeseed oils in order to investigate the influence of biodiesel composition on phase behaviour. In the systems water – butanol – FABE, glycerol – butanol – FABE and water – glycerol – FABE, the phase behaviour was experimentally determined and presented in ternary plots with corresponding binodal curves, equilibrium compositions and tie lines. The equilibrium was determined at 25°C and atmospheric pressure. Additionally, physical and chemical properties of biodiesel, such as viscosity, density, surface tension and pour point were measured. Beside these measurements, biodiesel was also examined using differential scanning calorimetry (DSC) and thermogravimetry (TGA).
The composition of biodiesel, as well as the presence of impurities and unreacted synthesis reactants, were analysed using gas chromatography. Complete miscibility was found in the binary systems water – glycerol and glycerol – butanol, while partial miscibility was found in the system water – butanol. Complete immiscibility of biodiesel with water and glycerol was also confirmed. The composition of biodiesel does not affect phase behaviour, only the physical properties of biodiesel
Respond of CHP plant on variation of outdoor temperature
No full textOvaj rad detaljno istražuje kako promjene vanjske temperature utječu na karakteristike kogeneracijskih postrojenja, koja su ključna za istovremenu proizvodnju električne i toplinske energije. Fokusirajući se na održavanje zadanog omjera ukupno proizvedene električne i toplinske energije te visokog toplinskog faktora iskorištenja, postrojenje prilagođava svoju proizvodnju pare sezonskim potrebama. Osim toga, istražuje se kako te promjene utječu na termodinamički stupanj iskorištenja i proizvedenu električnu energiju, pri čemu promjene ovise o tome je li proizvodnja pare konstantna ili ne. Naglašava se važnost kontinuiranog upravljanja postrojenjem kako bi se postigla maksimalna učinkovitost i ekonomičnost.
Rad također pruža sveobuhvatan pregled osnovnih principa kogeneracije, termodinamičkih osnova i tehnologija kogeneracije, uključujući detaljnu analizu rada parne turbine s reguliranim oduzimanjem pare te analizira prikupljene podatke o radu kogeneracijskih postrojenja u različitim uvjetima temperature.In this thesis, the extensive investigation focuses on how changes in external temperature influence the characteristics of cogeneration plants, which are vital for the simultaneous production of electrical and thermal energy. The study emphasizes maintaining the specified power to heat ratio and a high thermal efficiency factor, enabling the plant to adjust its steam production to seasonal needs. Additionally, the research explores how these changes impact thermodynamic efficiency and produced electrical energy, with variations depending on whether steam production is constant or not. Stressing the importance of continuous management to achieve maximum efficiency and cost-effectiveness, the thesis provides a comprehensive overview of the basic principles of cogeneration, thermodynamic fundamentals, and cogeneration technologies, including a detailed analysis of steam turbines with regulated steam extraction. The study also includes an analysis of collected data on the operation of cogeneration plants under different temperature conditions
Investigation of the influence of bioreactor properties on the composting process of biowaste
No full textU ovome radu, provedena su dva pokusa (P1 i P2) kompostiranja u dva reaktora (R1 i R2) različitih karakteristika, radnih volumena, Vr = 10 L. Cilj ovih pokusa bio je odrediti utječu li karakteristike reaktora na proces kompostiranja kao i sastav biootpada. Pokus P1 provodio se 16 dana, a sastav biootpada nije bio definiran, dok u pokusu P2 sastav biootpada je bio definiran i provodio se 14 dana. U određenim vremenskim periodima, ovisno o temperaturi, izuzimao se uzorak supstrata i određivani su fizikalno-kemijski pokazatelji (pH-vrijednost uzorka, koncentracija otopljenog kisika, električna provodnost, sadržaj vlage, hlapive i suhe tvari u uzorku) i mikrobiološki pokazatelji (ukupan broj živih bakterija i gljiva). Po završetku pokusa, u priređenim eluatima supstrata te uzorcima procjedne vode provedena je i analiza ukupnog organskog ugljika, TOC (eng. Total organic carbon) te test ekotoksičnosti pomoću morske bakterije Vibrio fischeri. Maksimalna postignuta temperatura u P1 bila je 33,4 ℃ u R1 i 36,1 ℃ u R2, dok je u P2 postignuta maksimalna temperatura od 43,3 ℃ u R1 i 44,7 ℃ u R2. pH-vrijednost supstrata u P1 porasla je s 5,13 na 7,79 u R1 i na 7,84 u R2, a tijekom drugog pokusa sa 6,11 na 8,58 u R1 i na 8,45 u R2. Rezultati testa ekotoksičnosti pokazali su da su eluati supstrata i procjedne vode u oba pokusa toksični. U pokusu P1 postignuta je konverzija od 24,99 % u R1 i 23,76 % u R2, a u P2 37,19 % u R1 i 56,92 % u R2.In this paper, two experiments (P1 and P2) of composting were carried out in two reactors (R1 and R2) with different characteristics and working volume of Vr = 10 L. The aim of these experiments was to determine whether the reactor characteristics affect the composting process as well as the composition of biowaste. Experiment P1 was conducted for 16 days, and the composition of biowaste was not defined, while in experiment P2, the composition of biowaste was defined and experiment was conducted for 14 days. In certain periods, depending on the temperature, a sample of the substrate was taken and physicochemical indicators (pH-value of the sample, concentration of dissolved oxygen, electrical conductivity, moisture content, volatile and dry substances in the sample) and microbiological indicators (total number of living bacteria and fungi) were determined. At the end of the experiment, an analysis of total organic carbon, TOC and ecotoxicity test using the marine bacterium Vibrio fischeri were performed on substrate samples and leachate samples. The maximum temperature achieved in P1 was 33,4 ℃ in R1 and 36,1 ℃ in R2, while in P2 the maximum temperature achieved was 43,3 ℃ in R1 and 44,7 ℃ in R2. During experiment P1, the pH value of the substrate increased from 5,13 to 7,79 in R1 and 7,84 in R2, and during experiment P2 from 6,11 to 8,58 in R1 and 8,45 in R2. The results of the ecotoxicity test showed that the substrate eluates and leachate were toxic in both experiments. A conversion of 24,99 % in R1 and 23,76 % in R2 of the experiment P1 and 37,19 % in R1 and 56,92 % in R2 of the experiment P2 was achieved