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PHENOLIC COMPOSITION AND ANTIOXIDANT ACTIVITY OF SEA FENNEL (CRITHMUM MARITIMUM L.) EXTRACTS OBTAINED BY DIFFERENT EXTRACTION METHODS : bachelor thesis
No full textMotar (Crithmum maritimum L.) je poznati mediteranski samonikli halofit za kojim interes u posljednje vrijeme neprestano raste zbog njegovih brojnih bioaktivnih spojeva, među kojima su najistraživaniji fenolni spojevi. Cilj ovog rada bio ispitati sadržaj ukupnih fenola, flavonoida, tanina i individualnih fenolnih kiselina u ekstraktima motra pripravljenim različitim metodama ekstrakcije pri različitim uvjetima, kao i antioksidacijsku aktivnost ekstrakata. U svrhu usporedbe konvencionalne ekstrakcije i nekonvencionalnih metoda korištena su tri postupka s različitim čimbenicima ekstrakcije, i to kako slijedi: mikrovalna ekstrakcija (MAE) sa snagom mikrovalova od 300 W, 500 W, 700 W, ultrazvučna ekstrakcija (UAE) pri sobnoj temperaturi, 40°C i 60°C, te konvencionalna metoda ekstrakcije maceracijom uz miješanje pri sobnoj temperaturi, 40°C i 60°C. Najveći ekstrakcijski prinos ukupnih fenola i flavonoida zabilježen je kod MAE pri snazi mikrovalova 300 W. Za izolaciju ukupnih tanina najboljom se pokazala UAE pri sobnoj temperaturi, dok je MAE s 700 W postignut približno jednak sadržaj ovih spojeva. Koncentracije individualnih fenolnih kiselina u ekstraktima određene su primjenom tekućinske kromatografije visoke djelotvornosti pri čemu su klorogenska kiselina i njeni derivati detektirani kao najzastupljeniji. Neoklorogenska i kriptoklorogenska kiselina su u najvišem udjelu bile prisutne u MAE pripravljenim s 700 W, dok je najviši udio klorogenske kiseline zabilježen u ekstraktima dobivenim MAE s 500 W. Antioksidacijska aktivnost uzoraka je testirana DPPH i FRAP metodom pri čemu su uzorci ekstrahirani s MAE očekivano pokazali najbolja svojstva. Na temelju dobivenih rezultata može se zaključiti da metode ekstrakcije i uvjeti provedbe istih imaju utjecaj na izolaciju fenolnih spojeva te je potvrđeno da sadržaj fenolnih spojeva ima direktni utjecaj na antioksidacijsku aktivnost uzoraka.Sea fennel (Crithmum maritimum L.) is a well-known Mediterranean wild halophyte, for which there has been a growing interest recently due to its richness in bioactive compounds, of which phenolic compounds are the most studied. The aim of this research was to investigate the content of total phenolics, flavonoids, tannins and individual phenolic acids, as well as their antioxidant activity in extracts obtained by different extraction methods performed under different conditions. Conventional and unconventional methods were compared as follows: microwave extraction (MAE) with microwave powers of 300 W, 500 W, 700 W, ultrasonic extraction (UAE) at room temperature, 40°C, 60° C and the conventional method with stirring at room temperature, 40°C, 60°C. The highest extraction yield of total phenols and flavonoids was obtained with MAE at 300 W. For the isolation of total tannins, UAE at room temperature proved to be the best method, with MAE at 700 W achieving approximately the same value. Phenolic acids conentrations were determined by high-performance liquid chromatography, with chlorogenic acid and its derivatives shown to be the most representative. Neochlorogenic and cryptochlorogenic acids were most represented in the extracts obtained with MAE at 700 W, while the highest concentration of chlorogenic acid was recorded in the extracts obtained with MAE at 500 W. The antioxidant activity of the samples was tested by the DPPH and FRAP methods, and as expected, the samples extracted with MAE showed the best antioxidant properties. The results suggest that the extraction method and conditions have an influence on the isolation of phenolic compounds and that the phenolic compound content affects the antioxidant activity of the samples
Application of diffraction techniques in the analysis of food supplements : bachelor thesis
No full textDodaci prehrani obogaćuju svakodnevnu prehranu s primarnim zadatkom oĉuvanja zdravlja. Upravo zbog svih benefita koje pruţaju ljudskom organizmu, potrebno je zadovoljiti dnevne potrebe vitamina i minerala, no naţalost to je sve teţe zbog suvremenog naĉina ţivota i nedostatka raznolikosti u rutinskoj prehrani ljudi. Najuĉestaliji dodaci koji se koriste kao nadomjestak hrani su vitamini, minerali i biljni ekstrakti. U poslijednje vrijeme dostupnost razliĉitih pripravaka od razliĉitih proizvoĊaĉa je lakša nego ikada do sada. Osim toga, prodaja ovih pripravaka je i medijski popraćena na naĉin da se kupce stimulira na kupovinu istih kroz navoĊenje niza djelotvornih uĉinaka na zdravlje poput smanjenja apetita, povećanja mišićne mase, poboljšanja pamćenja i cirkulacije itd. Spomenuta kategorija pripravaka smatra se hranom zbog ĉega je zakonska regulativa manje rigorozna u usporedbi s kontrolom lijekova koji podlijeţu strogim ispitivanjima. Uobiĉajene analitiĉke metode koje se primjenjuju u analizi dodataka prehrani su kromatografske i spektroskopske metode. U ovom radu korištena je rendgenska difrakcijska analiza (XRD) na praškastim, polikristalnim uzorcima mineralnih dodataka prehrani u cilju utvrĊivanja uĉinkovitosti iste u analizi dodataka prehrani.Dietary supplements enrich the daily diet with the primary task of maintaining health. Precisely because of all the benefits they provide to the human body, it is necessary to meet the daily needs of vitamins and minerals, but unfortunately this is increasingly difficult due to the modern way of life and the lack of variety in the routine diet of people. The most common supplements used as food substitutes are vitamins, minerals and plant extracts.Recently, the availability of various preparations from different manufacturers is easier than ever. In addition, the sale of these preparations is accompained by the media in such a way as to stimulate customers to buy them by stating a number of effective effects on health, such as reducing appetite, increasing muscle mass, improving memory and circulation, etc. The mentioned category of preparations is considered as food, therefore the legal regulations are less strict than for medicinal products, which are subject to strict control. Common methods of analysis for food supplements are chromatographic and spectroscopic methods. In this work, X-ray diffraction analysis (XRD) was used on powdered, polycrystalline samples of mineral food supplements in order to determine the effectiveness of the same in supplement analysis
Influence of process parameters of fluidized catalytic cracking (FCC) on the quality of basic products : diploma thesis
No full textProces fluidiziranog katalitičkog krekiranja (engl. fluidized catalytic craking (FCC)) jedan je od najvažnijih sekundarnih procesa rafinerijske prerade nafte. U Rafineriji nafte Rijeka INA d.d., FCC postrojenje izgrađeno je 1981. godine prema američkoj tehnologiji UOP, a sastoji se od katalitičke sekcije, sekcije za frakcioniranje, sekcije koncentracije plina te sekcije za merkaptansku oksidaciju (engl. merox) plina i benzina. Osnovna svrha procesa je cijepanjem ugljikovodičnih molekula težih frakcija nafte (ostatka procesa hidrokrekiranja, vakuumskog plinskog ulja) dobiti lakše i vrijednije produkte ugljikovodika pri visokoj temperaturi i umjerenom tlaku u prisustvu fino raspodijeljenog zeolitnog katalizatora. Glavni proizvod procesa je FCC benzin, jedna od temeljnih sastavnica motornog benzina za komercijalnu upotrebu te ukapljeni naftni plin (UNP), koji sadrži visok udio olefina, posebice propilena, vrijedne petrokemikalije. Stoga se danas sve više pažnje tijekom FCC procesa usmjerava i na iscrpak propilena. U ovom radu cilj je bio analizirati svojstva ulazne sirovine FCC procesa, pratiti procesne veličine tj. parametre tijekom probne proizvodnje te utvrditi njihov utjecaj na svojstva proizvoda, posebice na kvalitetu FCC benzina.The fluidized catalytic cracking process (FCC) is one of the most important secondary processes in oil refinery processing. In the Rijeka INA oil refinery , the FCC plant was built in 1981 to the American UOP technology, and consists of a catalytic section, a fractionation section, a ga s concentration section and merkaptane oxidation section (merox) of gas and gasoline. The main purpose of the process is to split hydrocarbon molecules of heavier fractions of oil (hydrocraking residue, vacuum gas oil) to obtain lighter and more valuable hydrocarbon products at high temperature and moderate presure in the presence of a finely dispersed zeolite cataylist. The main products of the process are FCC gasoline, one of the main components of motor gasoline for commercial use, and liquid petroleum gas (LPG), which contains a high fractions of olefins, especially propylene, valuable petrochemical. Therefore, more attention is focused on the extractio n of propylene in the FCC process. In this paper, the goal was to analyze the properties of the input raw material of the FCC process, to monitor the process variables (parameters) during trial production and to determine their influence on the product properties, especially on the quality of the FCC gasoline
Removal of zinc from the aqueous solution on different bisorbents - the impact of the solid/liquid ratio : master thesis
No full textSvakodnevna emisija teških metala u okoliš rezultat je čovjekovog djelovanja, najčešće industrije, rudarenja, neadekvatnog zbrinjavanja i spaljivanja otpada te primjene pesticida i umjetnih gnojiva. Takvi antropogeni izvori značajno onečišćuju vode u prirodi te je nužno pronaći ekološki i ekonomski prikladnu metodu uklanjanja teških metala iz voda. U ovome diplomskom radu ispitana je mogućnost korištenja čvrstog otpada/nusproizvoda (koštice maslina, pelet od komine maslina, ostaci hridinskog ježinca, koštice trešanja i koštice višanja) iz lokalnih pogona za proizvodnju i preradu hrane kao biosorbenasa u obradi otpadne vode onečišćene cinkom (c o = 193,9 mg/L). Sorpcija cinka provedena je šaržnim postupkom u trajanju od 24 h, pri omjerima kruto/tekuće u rasponu S/L = 0,25/50 ‒ 2,5/50. Svi ispitani biosorbensi pokazali su određeni potencijal za pročišćavanje voda onečišćenih cinkom. Najveća učinkovitost uklanjanja za sve biosorbense postignuta je pri najvećem S/L omjeru od 2,5/50; kako slijedi: 69,5% za koštice višanja, 46,8% za koštice maslina, 35,8% za ostatke hridinskog ježinca, 29,0% za pelet od komine maslina te 26,8% za koštice trešanja. Unatoč visokoj učinkovitosti uklanjanja od ≈ 70% na košticama višanja, zaostala koncentracija cinka od 59,1 mg/L veća je od maksimalno dopuštene koncentracije od 2 mg/L propisane pravilnikom, za ispust obrađene vode u sustav javne odvodnje i u prirodne recipijente. Buduća istraživanja trebalo bi usmjeriti na smanjenje koncentracije cinka do zakonom propisanih vrijednosti. Uporabom čvrstog otpada/nusproizvoda u navedenu svrhu smanjila bi se njegova izvorna količina koja bi neiskorištena mogla završiti na odlagalištu, a spaljivanjem zasićenih biosorbenasa u kontroliranim uvjetima omogućilo bi se dobivanje energije iz otpada. Takav način iskorištenja otpada smanjio bi ukupne troškove obrade voda te pridonio načelima održivog razvoja i zero-waste.The daily emission of heavy metals into the environment is the result of human activity, most often industry, mining, inadequate disposal and waste incineration, as well as application of pesticides and artificial fertilizers. Such anthropogenic sources significantly pollute water in nature, therefore is necessary to find an ecologically and economically suitable method for heavy metals removal from water. In this diploma thesis, the possibility of using solid waste/by-products (olive pits, olive pomace pellets, remains of sea urchin, cherry pits and sour cherry pits) from local plants for food production and processing as biosorbents in the treatment of wastewater contaminated with zinc (co = 193.9 mg/L) was investigated. Zinc sorption was carried out by a batch process during 24 h, with solid/liquid ratios in the range S/L = 0.25/50 - 2.5/50. All tested biosorbents showed a certain potential for purifying zinc-contaminated water. The highest removal efficiency for all biosorbents was achieved at the highest S/L ratio of 2.5/50, as follows: 69.5% for cherry pits, 46.8% for olive pits, 35.8% for the remains of sea urchin, 29.0% for olive pomace pellets and 26.8% for cherry pits. Despite the high removal efficiency of ≈ 70% on cherry pits, the residual zinc concentration of 59.1 mg/L is higher than the maximum permissible concentration of 2 mg/L, according to the Croatian legislation for the discharge of treated water into the public sewage system and into natural recipients. Future research should be focused on reducing zinc concentration below the prescribed value. Using solid waste/by-products for the stated purpose would reduce its original amount that could end up in a landfill, and by burning saturated biosorbents under controlled conditions, it would be possible to obtain energy from waste. Such a way of using waste would reduce the total costs of water treatment and contribute to the principles of sustainable development and zero waste
Adsorption equilibrium of Cu- and Ni- ions from binary solutions on zeolites 5A and 13X : diploma thesis
No full textU ovom diplomskom radu ispitivana je ravnotežna adsorpcija bakrovih i niklovih iona kao teških metala iz odgovarajućih binarnih otopina na zeolitima 5Å i 13X. Adsorpcija je provedena u šaržnom reaktoru, pri različitim početnim koncentracijama binarnih otopina, stalnoj temperaturi od 298 K, brzini miješanja od 200 okr min-1, u trajanju eksperimenta od 96 h. Ispitan je utjecaj ravnotežnih koncentracija iona teških metala na ravnotežne količine adsorbiranih iona teških metala te je uočeno da one rastu s povećanjem ravnotežnih koncentracija binarnih otopina, osim za adsorpciju niklovih iona na zeolitu 13X. Učinkovitost adsorpcije iona teških metala na zeolitima 5Å i 13X opada s porastom početne koncentracije binarne otopine. Dobiveni eksperimentalni podatci testirani su Langmuirovom, Freundlichovom, Tothovom, Redlich-Petersonovom i Sipsovom izotermom. Procjenom kvalitete slaganja adsorpcijskih modela s eksperimentalnim podatcima, usporedbom izračunatih vrijednosti maksimuma kapaciteta adsorpcije i eksperimentalno dobivenog te statističkih parametara za RMSE i r2, može se zaključiti da najbolje slaganje s eksperimentalnim podatcima pokazuju Freundlichov i Sipsov model za adsorpciju bakrovih iona na oba zeolita, dok kod adsorpcije niklovih iona na zeolitu 5Å najbolje slaganje pokazuju Freundlichov i Redlich-Petersonov model. Kod adsorpcije niklovih iona na zeolitu 13X niti jedan model ne pokazuje zadovoljavajuće slaganje.In this diploma thesis, the adsorption equilibrium of copper and nickel ions as heavy metal ions from the corresponding binary solutions on zeolites 5Å and 13X was investigated. Adsorption was carried out in a batch reactor at different initial concentrations of binary solutions, at a constant temperature of 298 K, a stirring speed of 200 rpm for 96 h. The impact of heavy metals equilibrium concentrations on the equilibrium amount of heavy metals adsorbed was investigated and it was found to increase as the equilibrium concentrations of heavy metals in the binary solutions rises, except for the adsorption of nickel ions on zeolite 13X. The adsorption efficiency of heavy metal ions on the zeolites 5Å and 13X decreases with the initial concentration of binary solution. The experimental data obtained were tested on Langmuir, Freundlich, Toth, Redlich-Peterson and Sips isotherms, respectively. By estimating the agreement quality of adsorption models with experimental data, by comparing calculated maximum adsorption capacity values with experimentally obtained, and comparing statistical parameters for RMSE and r2, it can be concluded that the best agreement with the experimental data showed Freundlich and Sips model for the adsorption of copper ions on both zeolites. For the adsorption of nickel ions on the zeolite 5Å, the best agreement showed Freundlich and Redlich-Peterson model while for the adsorption of nickel ions on zeolite 13X, none of the models showed satisfactory agreement
Synthesis and characterization of MgO from sea bittern with addition of poly (vinyl-alcohol) : master thesis
No full textIspitivao se utjecaj dodatka poli(vinil–alkohola) kao surfaktanta tijekom sinteze na veličinu i aglomeraciju čestica magnezijeva oksida istaloženog iz gorke morske vode. Sinteza se vršila procesom precipitacije u stehiometrijskom odnosu sa zasićenom vodom vapnenicom kao taložnim reagensom. Poli(vinil–alkohola) dodavao se u masenom omjeru (1:4) i (1:5) u odnosu na masu magnezijeva hidroksida koji se procesom dobiva. Uzorci su karakterizirani kemijskom analizom, TG/DTG, TEM analizom te je određena raspodjela veličina čestica. Dobiveni rezultati ukazuju na pozitivan utjecaj dodatka surfaktanta jer je mikrostruktura svih uzoraka ujednačena, utječe na smanjenje veličine čestica i sprječava nakupljanje čestica ali ne sprječava potpuno stvaranje aglomerata. Nastali aglomerati su manji vjerojatno zbog manjih čestica koje su nastale zbog prisutnosti poli(vinil–alkohola) tijekom sinteze. Povećanjem dodatka poli(vinil–alkohola) smanjuje se veličina čestica dobivenog taloga magnezijevog oksida te se dobivaju aglomerati srednje veličine čestica 1034,18 nm.The effect of the addition of poly(vinyl–alcohol) as a surfactant during synthesis on the size and agglomeration of magnesium oxide particles precipitated from sea bittern was studied. The synthesis was carried out by a stoichiometric precipitation process using saturated limestone water as precipitation reagent. Poly(vinyl–alcohol) was added in a mass ratio of (1:4) and (1:5) in proportion to the mass of magnesium hydroxide obtained by the process. The samples were characterized by chemical analysis, TG/DTG, TEM analysis, and determination of particle size distribution. The results obtained indicate a positive influence of the addition of surfactants, since the microstructure of all samples is uniform, the particle size is reduced and the accumulation of particles is prevented, but the formation of agglomerates is not completely prevented. The resulting agglomerates are smaller, likely due to the smaller particles formed by the presence of poly(vinyl–alcohol) during synthesis. With increasing addition of poly(vinyl– alcohol), the particle size of the resulting magnesium oxide precipitate decreases and agglomerates with an average particle size of 1034.18 nm are obtained
ELECTROCHEMICAL AND SPECTROPHOTOMETRIC CHARACTERIZATION OF ANTIOXIDANT ACTIVITY OF DALMATIAN PLANT EXTRACTS : diploma thesis
No full textAntioksidacijsko djelovanje prirodnih spojeva koji se nalaze u začinima, odnosno bilju procijenjeno je korištenjem elektrokemijskih i spektrofotometrijskih metoda. Odabrane su karakteristične biljke dalmatinskog područja: ružmarin, lovor i smilje. U svrhu postizanja što bolje ekstrakcije testirane su 4 metode ekstrakcije bioaktivnih tvari iz vodenih pripravaka. Izrađena je elektroda od pirolitičkog grafita, površine 7,5×10 -4 cm 2 , uz hipotezu kako će upravo izvanredne osobine ovog materijala omogućiti i olakšati prijenos elektrona između analita i elektrode. Optimiranjem parametara diferencijalne pulsne voltamtrije (DPV) pronađeni su uvjeti koji su dali visoku osjetljivost, selektivnost i reproducibilnost rezultata. Faktor 35,8 mA/cm 2 ukazao je na visoku osjetljivost i dobru linearnost (R 2 =0,980) predložene metode. Uz odabrane parametre određena je koncentracija galne kiseline u realnim uzorcima DPV metodom. Koncentracija ukupnih fenola i antioksidacijska aktivnost određena je i spektrofotometrijskim (SP) metodama. Kao najbolja metoda ekstrakcije prometnula se mikrovalna ekstrakcija za uzorke ružmarina i lovora, a jednostavna ekstrakcija na 100 ºC u trajanju od 5 minuta za ekstrakte smilja. Najveća koncentracija galne kiseline SP metodom uočena je u ekstraktu smilja, 917,1 mg dm -3 , a najveća antioksidacijska aktivnost zabilježena je u ekstraktu ružmarina potpomognuto mikrovalovima, 6406,4 μM Fe 2+ . Isti trend slijede i rezultati DPV metode. U svrhu procjene primjene elektrokemijskih metoda za određivanje galne kiseline, odnosno ukupnih fenola, napravljena je matematička korelacija između DPV i SP metoda. Konstantan odnos koncentracije galne kiseline dobiven DPV i SP metodom u iznosu približno 5,62 sugerira kako je predložena metoda pogodna za procjenu ukupnih fenola u realnim uzorcima.The antioxidant activity of small natural compounds found in spices and herbs was evaluated using electrochemical and spectrophotometric methods. The characteristic plants of the Dalmatian region were selected: rosemary, bay leaf and immortelle. In order to achieve the best possible extraction, 4 methods for the extraction of bioactive substances from aqueous preparations were tested. An electrode was made of pyrolytic graphite with a surface area of 7,5×10 -4 cm 2 , hypothesizing that the exceptional properties of this material would enable and facilitate electron transfer between the analyte and the electrode. By optimizing the parameters of differential pulse voltammetry (DPV), conditions were found that ensure high sensitivity, selectivity and reproducibility of results. The factor 35,8 mA/cm 2 indicates a high sensitivity and good linearity (R 2 =0,980) of the proposed method. Together with the selected parameters, the concentration of gallic acid in real samples was determined using the DPV method. The concentration of total phenols and antioxidant activity were also determined by spectrophotometric methods (SP). The best extraction method was microwave extraction for rosemary and bay leaf samples, simple extraction at 100 ºC for 5 minutes for the immortelle extract. The highest gallic acid concentration by SP method was found in immortelle extract (917,1 mg dm -3 ) and the highest antioxidant activity in microvawe-assisted rosemary extract (6406,4 μM Fe 2+ ). The results of DPV method follow the same trend. To evaluate the application of electrochemical methods for the determination of gallic acid or total phenolics, a mathematical correlation was established between the DPV and SP methods. The constant ratio of the gallic acid concentration determined by the DPV and SP methods of about 5,62 indicates that the proposed method is suitable for the estimation of total phenols in real samples
Corrosion behavior of Cu, CuAl and CuZnPb alloys in seawater : bachelor thesis
No full textU radu je ispitano korozijsko ponašanje Cu kao i legura CuAl i CuZnPb u mirujućoj morskoj vodi pri temperaturama 10, 20, 30 i 40°C, dok je utjecaj gibanja elektrolita ispitan pri 20°C uz miješanje magnetskom mješalicom, brzinom miješanja od 200 o min -1 . Ispitivanja su provedena elektrokemijskim metodama kao što su mjerenje potencijala otvorenog strujog kruga u periodu od 60 minuta, metodom linearne i potenciodinamičke polarizacije. Ispitivanja su pokazala da porast temperature morske vode ima značajan utjecaj na porast gustoće korozije struje i smanjenje vrijednosti polarizacijskog otpora, dok je utjecaj na vrijednost korozijskog potencijala gotovo zanemariv. Gibanje morske vode također ima negativan utjecaj na korozijsku nestabilnost Cu i Cu legura. Analiza površine uzoraka nakon elektrokemijskih ispitivanja optičkom mikroskopijom i optičkom profilometrijom, potvrdile su rezultate elektrokemijskih ispitivanja.In this work, the corrosion behavior of Cu, CuAl and CuZnPb alloys in still seawater was studied at temperatures of 10, 20, 30, and 40°C, while the influence of electrolyte agitation was investigated at 20°C mixing with a magnetic stirrer at a mixing speed of 200 rpm. The investigations were carried out by electrochemical methods such as measuring the open circuit potential over a period of 60 minutes, using the method of linear and potentiodynamic polarization. The tests showed that the increase in seawater temperature has a significant effect on the increase in corrosion current density and the decrease in the value of polarization resistance, while the effect on the value of corrosion potential is almost negligible. The movement of seawater also has a negative effect on the corrosion stability of Cu and Cu alloys. Analysis of the surface of the samples after the electrochemical test by optical microscopy and optical profilometry confirmed the results of the electrochemical test
Potentiometric sensors with the addition of magnetite nanoparticles for determination of iron(II) ions : diploma thesis
No full textIon-selektivne membrane pripravljene su od željezova(II) sulfida, srebrova(II) sulfida i politetrafluoretilena uz dodatak različitih udjela magnetita. Ispitivane su u otopini željezova(II) sulfata pri pH=4 i pri pH=5. Potenciometrijska metoda je korištena iz razloga što je jednostavna za provesti te ekonomski isplativa. Metodom slijednog razrjeđenja se provelo ispitivanje na odziv prema željezovim(II) ionima. Selektivnost potenciometrijske metode razmotrena je promjenom parametara koncentracije i pH otopine analita. Mjerenja se vrše dok vrijednost potencijala između dva mjerenja ne postigne vrijednost 1 mV. Rezultati su se pokazali negativnim te je poželjno nastaviti daljnje ispitivanje odziva željezovih(II) iona pri različitim uvjetima.Ion-selective electrodes were prepared from iron sulfide, silver sulfide and polytetrafluoroethylene with the addition of different percentages of magnetite. They were tested in iron(II) sulfate solution at pH=4 and pH=5. The reason why the potentiometric method was used is its simplicity of implementation, low price or good profitability. The test was carried out by the method of sequential dilution on the response to iron(II) ions. The selectivity of potentiometry was considered by changing the concetration and pH parameters of the analyte solution. Measurements are made until the potential value between two measurements reaches a value of 1 mV. The results turned out to be negative and it is desirable to continue further testing of iron(II) ions under different conditions
Microwave - assisted one-pot synthesis of 1,3 - thiazoles starting from primary alcohols : diploma thesis
No full textTiazol je peteročlani prsten koji sadrži atome dušika i sumpora na položajima 1 i 3. Tiazol je dobio značajnu pozornost u područjima organske i medicinske kemije zbog svojih izvanrednih bioloških i farmakoloških svojstava. Spojevi na bazi tiazola pokazaju širok spektar bioloških aktivnosti, uključujući antimikrobna, antitumorska, protuupalna i antioksidacijska djelovanja. Istraživanje derivata tiazola rezultiralo je razvojem brojnih komercijalno dostupnih lijekova koji sadrže tiazolski prstenasti sustav. Primjeri ovih lijekova uključuju ritonavir, sulfatiazol, bleomicin, pramipeksol, febuksostat, vitamin B 1 i mnoge druge. Ovi farmaceutski proizvodi ističu raznoliki terapijski potencijal spojeva na bazi tiazola. Glavni zadatak ovog rada bio je razviti praktičnu i učinkovitu metodu sinteze 1,3-tiazola in situ. Primarni cilj bio je otkriti nove sintetske puteve za dobivanje tiazola koristeći jednostavnije i dostupnije početne materijale. Ova metodologija je izvedena integracijom Hantzschove reakcije s mikrovalnim zračenjem. U početku su se koristili alkoholi koji su se pretvarali u α-halokarbonilne spojeve putem oksidacije i kloriranja. Za oksidaciju je korišten 2,2,6,6-tetrametilpiperidin-1-il-oksi radikal (TEMPO), dok je trikloroizocijanurna kiselina (TCCA) služila kao izvor klora. Nakon toga, proces Hantzschove sinteze je nastavljen, što je dovelo do formiranja 1,3-tiazola. Upotreba mikrovalnog zračenja rezultirala je bržom reakcijom, poboljšanim prinosima čistih produkata i pojednostavljenim postupcima obrade. Ovo istraživanje je pokazalo brojne prednosti mikrovalnog zračenja u odnosu na konvencionalne metode zagrijavanja.Thiazole is a five-membered moiety composed of nitrogen and sulfur atoms at positions 1 and 3, respectively. It has received significant attention in the fields of organic and medicinal chemistry due to its remarkable biological and pharmacological properties. Thiazole- based compounds have demonstrated a wide range of biological activities, including antimicrobial, antitumor, anti-inflammatory, and antioxidant activities, among others. The extensive exploration of thiazole derivatives has resulted in the development of numerous commercially marketed drugs that contain the thiazole ring system. Examples of these drugs include ritonavir, sulfathiazole, bleomycin, pramipexole, febuxostat, vitamin B 1 and many more. These pharmaceuticals highlight the diverse therapeutic potential of thiazole-based compounds. The main objective of this study was to develop a convenient and efficient one-pot synthesis method for 1,3-thiazoles. The primary aim was to discover novel synthetic routes for obtaining thiazoles utilizing more simple and available starting materials. This methodology was achieved by integrating the Hantzsch reaction with microwave irradiation. Initially, alcohols were utilized and transformed into α-halocarbonyl compounds through oxidation and chlorination. For oxidation, 2,2,6,6-tetramethylpiperidin-1-yl oxyl radical (TEMPO) was employed as the oxidant, while trichloroisocyanuric acid (TCCA) served as a chlorine source. Subsequently, the Hantzsch synthetic process proceeded, leading to the formation of 1,3-thiazoles. The utilization of microwave irradiation resulted in accelerated reaction rates, improved yields of pure products, and simplified workup procedures. This study demonstrated the numerous advantages of microwave irradiation over conventional heating methods