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Synthesis of compounds containing 3-phenyl-3-hydroxypropanoic subunit with liquid crystal properties : diploma thesis
No full textPripravljeni su homolozi nesimetriĉnih dimera kako bi se ispitala njihova mezogena svojstva. Dimeri posjeduju 3-fenil-3-hidroksipropansku podjedinicu povezanu esterskom vezom preko neparne alkilne razmaknice s cijanobifenilnom podjedinicom. Pripravljeni dimeri se razlikuju po duljini terminalnih lanaca. Kljuĉna reakcija u sintezi je Reformatskyjeva reakcija kojom je pripravljen etil-3-(4-(benziloksi)fenil)-3- hidroksipropanoat (2) na kojeg je u slijedećim koracima esterskom vezom vezan 4'-(3-hidroksipropil)-[1,1'- bifenil]-4-karbonitril (1). Spoj 1 pripravljen je Suzuki-Miyaura reakcijom. Uz pomoć polarizacijskog optiĉkog mikroskopa i diferencijalne pretražne kalorimetrije ispitana su mezogena svojstva ciljnih molekula. Oba spoja pokazuju svojstva tekućih kristala. Temeljem optiĉke teksture utvrĊeno je da se spojevi samoorganiziraju u antiklinalnu smektiĉku C fazu (SmC A ).H omologues of asymmetric dimers were prepared to examine their mesogenic properties. The dimers possess a 3-phenyl-3-hydroxypropane subunit which is linked to the cyanobiphenyl subunit by an ester bond via an odd alkyl spacer. The prepared dimers differ in the length of the terminal chains. The key reaction in the synthesis is the Reformatsky reaction to prepare ethyl-3-(4-(benzyloxy)phenyl) -3-hydroxypropanoate (2) to which 4'-(3-hydroxypropyl)-[1,1'-biphenyl]-4-carbonitrile (1) is attached in the following steps by an ester bond. Compound 1 was prepared by Suzuki-Miyaura reaction. The mesogenic properties of the target molecules were examined with the help of a polarizing optical microscope and differential scanning calorimetry. Both compounds show the properties of liquid crystals. Based on the optical texture, the compounds were found to self-organize into the anticline smectic C phase (SmCA)
Preparation and characterization of Fe(III)-modified zeolite-sorbent for Hg(II) removal from aqueous solutions : diploma thesis
No full textProvedena je kemijska modifikacija prirodnog zeolita porijeklom iz Vranjske Banje, Srbija s vodenom otopinom Fe(NO 3 ) 3 u acetatnom puferu pri pH = 3,6 te s otopinama NaOH i NaNO 3 . Za detaljnu komparativnu mineralošku i fizikalno-kemijsku karakterizaciju prirodnog i Fe(III)-modificiranog zeolita korišteni su klasična kemijska analiza, kisela i bazična svojstva određena Bohemovom metodom, kemijsko ponašanje pri različitim pH o vrijednostima, zeta potencijal pri različitim pH o vrijednostima, specifična površina, rendgenska difrakcijska analiza praškastog uzorka (XRPD), pretražna elektronska mikroskopija s energijsko disperzivnom rendgenskom spektroskopijom (SEM-EDS), infracrvena spektroskopija s Fourierovom transformacijom (FTIR) kao i termogravimetrijska analiza (TG-DTG) korišteni su. Modifikacijom nije došlo do promjena u strukturi i mineraloškom sastavu zeolita, a povećao se volumen pora i količina natrijevih iona kao rezultat ionske izmjene i neutralizacije negativnog naboja nastalog tijekom modifikacije. Dobiveni Fe(III)-modificirani zeolit pokazao je gotovo dvostruko veći kapacitet vezivanja Hg(II) u odnosu na prirodni, što opravdava metodu modifikacije prirodnog zeolita.Chemical modification of natural zeolite originated from the Vranjska Banja, Serbia deposit has been performed with the aqueous solution of Fe(NO 3 ) 3 at pH = 3.6 and with NaOH and NaNO 3 solutions. For detailed comparative mineralogical and physico-chemical characterization of natural and Fe(III)-modified zeolite the chemical analysis, acid and basic properties determined by Bohem’s method, chemical behavior at different pH o values, zeta potential, specific surface area, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive X-ray analysis (SEM- EDS), Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetry (TG-DTG) were used. The modification did not cause changes in the structure and mineralogical composition of the zeolite, but it increased the pore volume and the amount of sodium as a result of ion exchange and neutralization of the negative charge created during the modification. The obtained Fe(III)-modified zeolite has shown almost twice higher sorption capacity for Hg(II) compared to natural one, which justifies the method of modification of natural zeolite
Coordination polyimers of an iron(II) with the selected derivates of nicotinic acid : master thesis
No full textPripravljeni su koordinacijski polimeri željeza(II) i odabranih derivata nikotinske kiseline (2- bromnikotinska, 5-bromnikotinska i 6-klornikotinska kiselina) te 4,4'-bipiridina i 1,2-bispiridiletana. Željezov(II) klorid tetrahidrat korišten je kao metalna sol u sintezama, a voda, etanol i N,N'- dimetilformamid (DMF) korišteni su kao otapala u sintezama. Dobiveni produkti karakterizirani su IR spektroskopijom, termogravimetrijski (TGA) te diferencijalnom skenirajućom kalorimetrijom (DSC), a maseni udio željeza(III) u produktima određen je UV/Vis spektrofotometrijski.Coordination polymers of iron(II) and selected nicotinic acid derivatives (2-bromonicotinic, 5- bromonicotinic and 6-chloronicotinic acid) and 4,4'-bipyridine and 1,2-bis(pyridyl)ethane were prepared. Iron(II) chloride tetrahydrate was used as the metal salt, whilst water, ethanol, and N, N'- dimethylformamide (DMF) were used as solvents in the syntheses. The obtained products were characterized by IR spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The mass fraction of iron(III) in the prepared compounds was determined by UV/Vis spectrophotometry
Depassivation of tin in halogenide solution : bachelor thesis
No full textU ovom radu je proučavana depasivacija čistog kositra u otopini KI-a. Snimane su polarizacijske krivulje u anodnom području potencijala od -0.6 do 1.2 V, tj. do potencijala aktivnog anodnog otapanja uzorka. Ispitan je utjecaj koncentracije jodidnih iona (od 0.01 do 1 M), brzine promjene potencijala (od 1 do 100 mV s -1 ) te temperature elektrolita (od 10 do 30 o C). Neposredno prije izvođenja svih mjerenja, na površini Sn oksidacijom na zraku formiran je prirodni oksidni film. Anodnom polarizacijom kositra, nakon prolaska kroz pasivno područje potencijala, postiže se potencijal depasivacije pri kojem dolazi do razaranja oksidnog sloja i pojave lokalnog otapanja metala uz stvaranje sitnih rupica, „pitova“. Porastom koncentracije jodidnih iona potencijal depasivacije pomiče se prema negativnijim vrijednostima, dok se polarizacijski otpor značajno smanjuje. Također je primijećeno da potencijal depasivacije postaje pozitivniji ukoliko se promjena potencijala u pozitivnom smjeru ostvaruje brže, što znači da je za pojavu lokalne (jamičaste) korozije potrebno izvjesno vrijeme (indukcijsko vrijeme) nakon što se uspostavi stvarni potencijal depasivacije. Neovisno o pomaku potencijala depasivacije prema pozitivnijim vrijednostima, brzina promjene potencijala ne utječe na vrijednost polarizacijskog otpora. Porastom temperature otopine elektrolita potencijal depasivacije Sn postaje negativniji, dok se polarizacijski otpor lagano smanjuje.In this paper, the depassivation of tin in KI solution was studied. Polarization curves were recorded in the anode potential range from -0.6 to 1.2 V, i.e. to the active anodic dissolution potential of Sn. The influence of iodide ion concentration (from 0.01 to 1 M), potential scan rate (from 1 to 100 mV s -1 ) and electrolyte temperature (from 10 to 30 o C) was examined. Before performing all measurements, a natural oxide film was formed on the Sn surface (oxidation on air). By anodic polarization of tin, after passing through the passive potential range, a potential depassivation is achieved in which the oxide layer is destroyed and local metal dissolves with the formation of small holes, „pits“. Increasing the iodide ions concentration, the depassivation potential becomes more negative, while the polarization resistance decreases significantly. If the potential scan rate increases depassivation potential becomes more positive, meaning that a certain time (induction time) is needed for the pitting corrosion which occurs after the actual depassivation potential is established. The potential scan rate does not affect on the polarization resistance. As the temperature of the electrolyte solution increases, the depassivation potential of Sn becomes more negative, while the polarization resistance decreases slightly
Volumetric properties of solutions of imidazolium chloride ionic liquids ([min][Cl], [1.3-dmim][Cl], [emim][Cl], [bmim][Cl] and [hmim][Cl]) u butan-1-ol : bachelor thesis
No full textProvedena su mjerenja gustoća pet imidazolijevih kloridnih ionskih tekućina, ILs (mimCl, 1,3- dmimCl, emimCl, bmimCl i hmimCl) u organskom otapalu butan-1-olu i pri određenim temperaturama, / C = 5, 10, 15, 20, 25, 30, 35 i 40, korištenjem automatskog mjerača gustoće Anton Paar DMA 4500M. Dobiveni podaci korišteni su za daljnje računanje volumetrijskih svojstava - prividnih i parcijalnih molarnih volumena ispitivanih ILs u butan-1-olu. Korištenjem Massonove jednadžbe izračunati su prividni granični molarni volumeni i interakcijski koeficijenti. Također, izračunata je i prividna granična molarna ekspanzibilnost i Hepplerovi koeficijenti imidazolijevih kloridnih ionskih tekućina u butan-1-olu. Eksperimentalni rezultati su raspravljeni u svjetlu ion-ion i ion-otapalo interakcija te je provedena usporedba sa imidazolijevim kloridnim ILs u vodenom mediju.The density mesurements of five imidazolium chloride ionic liquids, ILs (mimCl, 1,3-dmimCl, emimCl, bmimCl and hmimCl) in butan-1-ol at diferent temperatures, / C = 5, 10, 15, 20, 25, 30, 35 i 40, were performed using Anton Paar DMA 4500M densimeter. The obtained data were used for calculation of volumetric properties – apparent molar volumes and partial molar volumes for investigated ILs in butan-1-ol. The volumetric data have been analyzed using Masson`s equation. The limiting apparent molar volume and the slope of Masson`s equation for imidazolium chloride ionic ILs in butan-1-ol and at diferent temperatures have been interpreted in terms of ion-ion and ion-solvent interactions. Also, the values for limiting apparent molar expansibilities and Heppler’s coefficients were calculated. The results were discussed and compared with the same ILs in water medium
Coordination polymers of a manganese(II) with selected haloderivates of nicotinic acid : diploma thesis
No full textPripravljeni su koordinacijski polimeri mangana(II) i odabranih halogenih derivata nikotinske kiseline (2-bromnikotinska, 5-bromnikotinska i 6-klornikotinska kiselina) te 4,4'-bipiridina i 1,2-bis(4- piridil)etana. Manganov(II) klorid tetrahidrat korišten je kao metalna sol u sintezama, a voda, etanol i N,N'- dimetilformamid (DMF) korišteni su kao otapala u sintezama. Dobiveni produkti karakterizirani su IR spektroskopijom i termogravimetrijski (TGA), a maseni udio mangana(II) u produktima određen je UV/Vis spektrofotometrijski. Određene su molekulske formule dvaju koordinacijskih polimera {[Mn(2 − Brnic) 2 (4,4 ′ − bpy)(H 2 O) 2 ] · 2(4,4 ′ − bpy)} n () i {[Mn (5 − Brnic) 2 (4,4 ′ − bpy)(H 2 O) 2 ] · 4,4 ′ − bpy · 2H 2 O} n () . Pretpostavlja se da je manganov(II) ion oktaedarski koordiniran s dva O-monodentatno vezana nikotinatna liganda, dvije molekule vode te s dvije molekule 4,4'-bipiridina u molekulskim strukturama dobivenih polimera te da molekule 4,4'-bipiridina premošćuju manganove(II) ione pri čemu nastaju jednodimenzijski polimerni lanci. U kristalnim strukturama prisutne su kokristalizacijske molekule 4,4'-bipiridina (spoj 1) odnosno 4,4'-bipiridina i vode (spoj 2).Coordination polymers of manganese(II) and selected nicotinic acid haloderivatives (2- bromonicotinic, 5-bromonicotinic and 6-chloronicotinic acid) and 4,4'-bipyridine and 1,2-bis(4- pyridyl)ethane were prepared. Manganese(II) chloride tetrahydrate was used as the metal salt, whilst water, ethanol, and N, N'- dimethylformamide (DMF) were used as solvents in the syntheses. The obtained products were characterized by IR spectroscopy and thermogravimetric analysis (TGA). The mass fractions of manganese(II) in the prepared compounds were determined by UV/Vis spectrophotometry. The molecular formulae of two coordination polymers were determined as {[Mn(2 − Brnic) 2 (4,4 ′ − bpy)(H 2 O) 2 ] · 2(4,4 ′ − bpy)} n () and {[Mn (5 − Brnic) 2 (4,4 ′ − bpy)(H 2 O) 2 ] · 4,4 ′ − bpy · 2H 2 O} n () . It is proposed that the manganese(II) ion is octahedrally coordinated with two O-monodentate nicotinate ligands, two water molecules and with two 4,4’- bipyridine molecules in the molecular structures of the obtained polymers. The 4,4'-bipyridine molecules bridge the manganese(II) ions leading to the formation of one-dimensional polymeric chains. There are 4,4'-bipyridine molecules of crystallization in the crystal structure of compound 1 and 4,4'-bipyridine and water molecules of crystallization in the crystal structure of compound 2
Hg(II) sorption onto natural and Fe(III) modified zeolite - effect of pH : bachelor thesis
No full textUtjecaj pH na sorpciju Hg(II) iz vodene otopine ispitan je na prirodnom i Fe(III)-modificiranom zeolitu. Sorpcija je provedena pri pH 2,09 i 2,30. Rezultati su pokazali da je optimalni pH = 2,09 dok je pri pH = 2,30 došlo do taloženja Hg(II) u suspenziji. Ralog tome su veće ravnotežne pH vrijednosti od izračunate pH vrijednosti od 2,45 pri kojoj dolazi do taloženja za početnu koncentraciju od 4,006 mmol Hg/L. Količina sorbirane Hg(II) na Fe(III)-modificiranom zeolitu je za 1,4 puta veća u odnosu na prirodnom zeolitu, dok je postignuta učinkovitost sorpcije Hg(II) 81% na Fe(III)-modificiranom zeolitu te 57% na prirodnom zeolitu.The effect of pH on the sorption of Hg (II) from aqueous solution was investigated on natural and Fe (III)-modified zeolite. Sorption was performed at pH 2.09 and 2.30. The results showed that the optimal pH is 2.09 while at pH = 2.30 precipitation of Hg (II) occurred in suspension. The reason for that are higher equilibrium pH values than the calculated pH value of 2.45 at which precipitation occurred for an initial concentration of 4.006 mmol Hg/L. The amount of sorbed Hg (II) onto Fe (III)-modified zeolite is 1.4 times higher than that natural zeolite, while the achieved sorption efficiency of Hg(II) is 81% on Fe (III)-modified zeolite and 57% on natural zeolite
Qualitative and quantitative determination of selected isothiocyanates and nitrilies using GC-MS/MS : bachelor thesis
No full textGlukozinolati su fitokemikalije iz kojih hidrolizom nastaju lako hlapljivi spojevi izotiocijanati i nitrili koji zbog svoje iskazane biološke aktivnosti predstavljaju temu od interesa. Plinska kromatografija je često korištena analitička tehnika kojom se odjeljuju komponente iz uzorka. Kombinacijom plinske kromatografije s tandemskom spektrometrijom masa postoji mogućnost identifikacije i određivanja lako hlapljivih spojeva. Cilj ovog rada bio je izraditi metodu za kvalitativnu i kvantitativnu analizu fenilacetonitrila, 3-fenilpropanonitrila, 2-feniletil-izotiocijanata i izopropil-izotiocijanata. Dobiveni rezultati pokazuju da su određivanje koncentracije i identifikacija odabrane komponente iz uzorka uspješne iz čega se moţe zaključiti da je metoda valjana.Glucosinolates are phytochemicals from which the easily volatile compounds isothiocyanates and nitriles are formed by hydrolysis which represent the topic of interest due to their biological activity. Gas chromatography is a widely used analytical technique that separates components from a sample. By combining gas chromatography with mass spectrometry, we have the ability to identify and quantify volatile compounds. The aim of this work was to develop a method for qualitative and quantitative analysis of phenylacetonitrile, 3-phenylpropanonitrile, 2-phenylethyl isothiocyanate and isopropyl isothiocyanate. The obtained results show that it is necessary to determine the concentrations and identify the selected components from the sample successfully from which it can be concluded that the method is valid
Electrchemical phenomena in diluted solutions of the supporting electrolyte and the effect on processes in the electrical double layer: voltametric and electrochemical impedance study of hexacyanoferate on a glassy carbon electrode : diploma thesis
No full textU ovom radu detaljno su proučavani fenomeni na heterogenoj dodirnoj površini faza uz odvijanje faradejske reakcije. Prethodno su razjašnjene pojave odgovorne za uspostavu elektrokemijskog potencijala bez i u prisutnosti Fe(CN) 6 4- kao elektroaktivne vrste. Detaljno su opisane pojave u dvosloju, odgovorne za različita elektrokemijska ponašanja Fe(CN) 6 4- u otopinama različite koncentracije osnovnog elektrolita (KCl). Nadalje, elektrokemijskom impedancijskom spektroskopijom dobiveni su uvidi u fenomene koji se događaju na različitim potencijalima snimljenih cikličkih voltamograma, pri različitim koncentracijama osnovnog elektrolita. Iako se ove dvije metode razlikuju u vremenskim okvirima eksperimenta, dobivene informacije daju dobar uvid u procese na elektrodi. Na kraju razjašnjeni su procesi odgovorni za različito ponašanje Fe(CN) 6 4- s promjenom brzine posmika u različitim koncentracijama osnovnog elektrolita. U ovom istraživanju korištene su dvije elektrode od staklastog ugljika s različitom konstantom heterogenog prijelaza elektrona. Za uvid u procese korištena je ciklička voltamterija i elektrokemijska impedancijska spektroskopija.In this paper, the phenomena that occurs on the heterogeneous contact surface of phases, with an ongoing Faraday reaction, were studied in detail. The phenomena responsible for the establishment of the electrochemical potential without and in the presence Fe(CN) 6 4- as an electroactive species have been previously clarified. The phenomena in the double layer, which are responsible for different electrochemical behaviors of Fe(CN) 6 4- in solutions with different concentrations of supporting electrolyte (KCl) are described in detail. Furthermore, electrochemical impedance spectroscopy provided insights into the phenomena that occur at different potentials of the recorded cyclic voltammograms, at different concentrations of the supporting electrolyte. Although these two methods differ in the time frames of the experiment, the obtained information gives a good insight into the processes at the electrode. Finally, the processes responsible for the different behavior of Fe(CN) 6 4- s with the change of the shear rate at different concentrations of the supporting electrolyte are explained. Two glassy carbon electrodes, with different heterogeneous electron transition constant, were used in this study. Cyclic voltammetry and electrochemical impedance spectroscopy were used for an insight of the processes
Characterization of microplastics from Zaglav beach on island of Vis : master thesis
No full textU ovom radu provedena je karakterizacija i identifikacija mikroplastike pronađene u sedimentu plaže Zaglav na otoku Visu. Uzorkovanje i separaciju uzoraka proveo je Institut za oceanografiju i ribarstvo u Splitu. Karakterizacija mikroplastike izvršena je na 865 uzoraka s plaže Zaglav na otoku Visu. Uzorci su vizualno analizirani i svrstani prema obliku definiranim prema DeFishGear protokolu: filamenti, filmovi, fragmenti, granule, peleti i pjene. Svakom pojedinačnom uzorku je vizualno određena prozirnost i boja, a masa vaganjem na analitičkoj vagi. Površina i maksimalna dimenzija svakog ispitka određeni su upotrebom Digimizer programskog paketa. Identifikacija vrste polimernog materijala o kojem je riječ provedeno je za 865 uzoraka uz pomoć FTIR spektroskopije i diferencijalne pretražne kalorimetrije, dok su sitniji uzorci ostavljeni za analizu naprednijim tehnikama. Ustanovljeno je da su fragmenti najzastupljenija kategorija, a uzorci su većinom neprozirni i bijele boje, čestice promjera manje od 5 mm što ih svrstava u kategoriju mikroplastike. Najzastupljenija vrsta polimernog materijala je polipropilen, nakon kojeg slijede polietilen visoke gustoće i polietilen niske gustoće. Rezultati koji su dobiveni ovim istraživanjem ukazuju da najveći broj uzoraka sedimenta plaže Zaglav na otoku Visu potječe od nepropisno odložene jednokratne ambalaže.This thesis shows characterization and identification of microplastic waste found in the Zaglav beach sediment on Vis island. Sampling and separation of samples was performed by the Institute of Oceanography and Fisheries in Split. Characterization of microplastic was performed on 865 specimens from the Zaglav beach on Vis island. Specimens were visually analysed and sorted into categories according to shape defined by DeFishGear protocol: filaments, films, fragments, granules, pellets and foams. Transparency and color of the individual specimens are visually determined and a mass was determined using an analytical balance. Area and maximum dimension were determined using software package Digimizer for image processing. Identification of the type of polymer material was performed by FTIR spectroscoopy and diferential scanning calorimetry, while other smaller specimens were left for the further analysis using more precisely methods. The most common category is fragments, spesimens are mostly white in color and opaque, particles less than 5mm in diameter which sorts them in category of microplastics. The most common type of polymer material is polypropylene, followed by polyethylene high density and polyethylene low density. Results obtained by this research show that most specimens from Zaglav beach originate from improperly discarded disposable packaging