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Synthesis of TiO2 nanopartlices by sol-gel method : bachelor thesis
No full textIstraživanja u ovom radu usmjerena su na sol-gel sintezu nanostrukturiranih čestica TiO 2 te karakterizaciju istih. Kao izvor titana korišten je titanijev n-butoksid ( Ti[O(CH 2 ) 3 CH 3 ] 4 ), a kao otapalo 96%-tni etanol odnosno apsolutni etanol uz dodatak HCl odnosno HNO 3 . Sinteze su provedene pri sobnoj temperaturi uz konstantno miješanje u trajanju od 4 sata. Kruta faza iz pripravljenih suspenzija je separirana od tekuće faze i osušena pri temperaturi od 80°C u trajanju od 1 odnosno 2 sata. Osušeni prah je zatim kalciniran pri temperaturi od 450°C u trajanju od 3 sata. Pripravljeni uzorci su karakterizirani difrakcijom rendgenskih zraka na polikristalnim uzorcima (XRD), infracrvenom spektroskopijom s Fourierovom transformacijom (FT-IR) te pretražnom elektronskom mikroskopijom (SEM). Rezultati istraživanja ukazuju da nakon provedenog sušenja pri 80 o C u uzorku D dolazi do kristalizacije strukturno uređenog TiO 2 u formi anatasa, u ostalim uzorcima produkt sol-gel reakcije je produkt koji nema strukturnu uređenost dugog dosega što ukazuje na amorfnu strukturu materijala. Nakon provedene kalcinacije pri 450 o C u trajanju od 3 sata u uzorku D dolazi do kristalizacije dvije strukturno uređene forme TiO 2 i to anatasa i brukita dok u ostalim uzorcima kristalizira čisti TiO 2 u formi anatasa.Research in this work is focused on sol-gel synthesis of nanostructured TiO 2 particles and their characterization. Titanium n-butoxide ( Ti[O(CH 2 ) 3 CH 3 ] 4 ) was used as a source of titanium, and 96% ethanol or absolute ethanol with the addition of HCl or HNO 3 . The syntheses were carried out at room temperature with constant stirring for 4 hours. Solid phase from the obtained milky suspension were separated and dried at a temperature of 80°C for 1 or 2 hours. The dried powder was then calcined at a temperature of 450°C for 3 hours. The prepared samples were characterized by X-ray diffraction on polycrystalline samples (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The research results indicate that after drying at 80 o C in sample D, have a structurally ordered phase of TiO 2 which crystallizes in the form of anatase, in other samples the product of the sol-gel reaction is a product which does not have a long-range structural order, what suggest on the amorphous structure. After calcination at 450 o C for 3 hours in sample D, two structurally ordered forms of TiO 2 crystallize, namely anatase and brookite, while pure TiO 2 crystallizes in the form of anatase in the other sample
Analysis of the response of the carbon paste electrode (with 2-nitrophenyl octyl ether as binder) for the determination of acebutolol : bachelor thesis
No full textZbog dobrih fizikalno-kemijskih svojstava u elektrokemijskim mjerenjima često se primjenjuju elektrode s ugljikovom pastom. Korištene komponente paste u ovom radu su: grafit, tekuće vezivo i ionsko- asocijacijski kompleks. Pripravljeno je i testirano 9 pasti u svrhu izrade primjenjivog senzora za potenciometrijsko određivanje acebutolola. Svaka pasta imala je različite omjere komponenata i različitu vrstu ionsko-asocijacijskog kompleksa. Za sve paste je korišteno isto vezivo (2-nitrofenil-oktil-eter). Najbolje odzivne karakteristike pokazala je elektroda 3 koja sadrži 58,6% grafita, 50,4% veziva (2-nitrofenil- oktil-eter) i 0,9% acebutololovog tetrafenilborata (Ac TPB) , a ostvareni nagib iznosi 50,7 mV po koncentracijskoj dekadi. Linearno područje je u rasponu koncentracija od 3,16∙10 -3 do 7,94∙10 -7 mol L -1 .Due to their good physical and chemical properties, Carbon paste electrodes are often used in electrochemical properties. The paste components used in this work are: graphite, liquid binder and ion- association complex. 9 pastes were prepared and tested for the purpose of creating an applicable sensor for the potentiometric determination of acebutolol. Each paste had different ratios of components and a different type of ion- association complex. The same binder (2-nitrophenyl octyl ether) was udes for all pastes. The best response characteristics were shown by electrode 3, which contains 58,6% graphite, 50,4% binder (2-nitrophenyl octyl ether) and 0,9% acebutolol tetraphenylborate (Ac TPB), and the achieved slope is 50,7 mV per concentration decades. The linear range is in the range of concentrations from 3,16∙10 -3 to 7,94∙10 -7 mol L -1
CORROSION AND ITS IMPACT ON SOCIETY : bachelor thesis
No full textU ovom radu opisuju se osnovni koncepti korozije, podijeljeni prema vrstama korozivne sredine, mehanizmima djelovanja i obliku oštećenja. Pregledom literature opisani su oblici korozije, faze nastanka korozije i njene posljedice. Također, obrađeno je korozijsko ponašanje željeza, aluminija, čelika, bakra i njihovih legura obzirom da se najčešće i najviše koriste kao konstrukcijski materijali. Analizirao se utjecaj temperature, kisele kiše, vlažnost zraka i drugi klimatski čimbenici koji potiču koroziju. Korozijski procesi uzrokuju velike troškove te je tendencija smanjenje istih. Prikazani su faktori koji utječu na smanjenje i povećanje ukupnih troškova korozije, a koji variraju od industrije do industrije. Korozija se javlja kod svih inženjerskih materijala, okolini, životu ljudi stoga ima veliki utjecaj na društvo što je vidljivo iz navedenih primjera. U negativnom smislu, korozija za posljedicu ima razne katastrofe dok u pozitivnom može biti dekorativna na građevinama izloženim različitim atmosferskim uvjetima.This paper describes the basic concepts of corrosion, divided into types of corrosive environments, mechanisms of action, and forms of damage. A literature review describes the different forms of corrosion, the stages of corrosion formation and its consequences. The corrosion behavior of iron, aluminum, steel, copper, and their alloys is also discussed, as these materials are most commonly and extensively used as construction materials. The influence of temperature, acid rain, humidity and other climatic factors that promote corrosion has been analyzed. Corrosion processes cause high costs, and there is a tendency to reduce them. The factors affecting the reduction and increase of total corrosion costs are presented and vary from industry to industry. Corrosion is present in all engineering materials, in the environment and in people's lives, and therefore has a major impact on society, as shown by various examples. In a negative sense, corrosion leads to various disasters, while in a positive sense it can be decorative for buildings exposed to various atmospheric conditions
The influence of sodium alginate on the thermal properties of polylactic acid : bachelor thesis
No full textModifikacija polilaktidne kiseline (PLA) provedena je dodatkom natrijevog alginata (NaAlg) s ciljem određivanja njegovog utjecaja na toplinska svojstva i kristalnost PLA. Uspješno su pronađeni optimalni uvjeti za predmiješanje početnih polimera kao i uvjeti ekstrudiranja na dvopužnom ekstruderu s kontrarotirajućim vijcima. Diferencijalna pretražna kalorimetrija (DSC) je primijenjena u svrhu istraživanja utjecaja NaAlg na toplinska svojstva i kristalnost PLA. Utvrđena je mješljivost mješavine PLA/NaAlg u istraživanom području sastava, te djelovanje NaAlg kao nukleacijskog agensa PLA. Prema istraživanju optimalan udio NaAlg je 2 mas.%.The modification of polylactide acid (PLA) was carried out by the addition of sodium alginate (NaAlg) with the aim of determining its influence on the thermal properties and crystallinity of PLA. Optimal conditions for premixing the initial polymers as well as extrusion conditions on a twin-screw extruder with counter-rotating screws were successfully found. Differential scanning calorimetry (DSC) was applied to investigate the effect of NaAlg on the thermal properties and crystallinity of PLA. The miscibility of the PLA/NaAlg blend in the investigated composition range, and the action of NaAlg as a nucleating agent of PLA, were determined. According to the research, the optimal proportion of NaAlg is 2 wt %
GREEN SYNTHESIS OF COLLOIDAL SILVER BY CHEMICAL REDUCTION USING GREEN TEA : diploma thesis
No full textZelena sinteza nanočestica je relativno nova grana nanotehnologije koja ima mnoge prednosti u odnosu na kemijske i fizičke metode sinteze nanočestica. Proces je siguran, jednostavan, isplativ, ekološki prihvatljiv, smanjuje količinu potrebne energije i često rezultira stabilnijim materijalima te nema potrebe za visokim temperaturama niti tlakovima. Zbog bogate bioraznolikosti biljaka i njihovih potencijalnih sekundarnih metabolita, biljke i dijelovi biljaka u novije su vrijeme dobro iskorišteni za sintezu raznih nanočestica. U ovom radu sintetizirano je koloidno srebro na ekološki način bez korištenja organskih ili toksičnih otapala. Sinteza je provedena korištenjem zelenog čaja kao redukcijskog i stabilizacijskog sredstva pri pH vrijednostima 6, 7, 8 i 9 uz korištenje otopine srebrovog nitrata koncentracije 0,001 mol dm -3 i otopine natrijevog karbonata koncentracije 0,1 mol dm -3 za podešavanje pH vrijednosti i destiliranu vodu kao otapalo. Zeleni čaj bogat je katehinima koji pripradaju grupi flavanola, a sudjeluju u reakciji redukcije srebrovih iona. Karakterizacija koloidnog srebra provedena je UV-Vis spektrofotometrom, FT-IR analizom uzoraka, DLS (Dynamic Light Scattering) analizom te pomoću određivanja Tyndallovog efekta propuštanjem laserske zrake kroz otopinu. Analiza dinamičog raspršenja svjetlosti je korištena za procjenu veličine nastalih nanočestica srebra i uniformnosti uzorka nastalih nanočestica, dok se UV-Vis spektrofotometrom dokazala prisutnost nanočestica srebra pojavom površinskog plazmona rezonancije. Raspon veličina dobivenih nanočestica kemijskom redukcijom pomoću otopine zelenog čaja je od 32 nm do 143 nm.Green synthesis of nanoparticles is a relatively new branch of nanotechnology that has many advantages over chemical and physical methods of nanoparticle synthesis. The process is safe, simple, cost- effective, environmentally friendly, reduces the amount of energy required and often results in more stable materials, and there is no need for high temperatures or pressures. Due to the rich biodiversity of plants and their potential secondary metabolites, plants and plant parts have been well utilized in recent times in the synthesis of various nanoparticles. In this work, colloidal silver was synthesized in an ecological way without the use of organic or toxic solvents. The synthesis was carried out using green tea as a reducing and stabilizing agent at pH values of 6, 7, 8 and 9 with the use of silver nitrate solution with a concentration of 0.001 mol dm- 3. Sodium carbonate solution with a concentration of 0.1 mol dm-3 was used to adjust the pH value and distilled water was used as a solvent. Green tea is rich in catechins that belong to the group of flavanols and participate in the reduction reaction of silver ions. The characterization of colloidal silver was carried out with a UV-Vis spectrophotometer, FTIR analysis, DLS (Dynamic Light Scattering) analysis and determination of the Tyndall effect by passing a laser beam through the solution. Dynamic light scattering analysis was used to assess the size of the silver nanoparticles and the uniformity of the sample, while the UV-Vis spectrophotometer was used to prove the presence of silver nanoparticles by the appearance of surface plasmon resonance. The size range of nanoparticles obtained by chemical reduction using green tea solution is from 32 nm to 143 nm
FOURIER TRANSFORM INFRARED SPECTROSCOPY ANALYSIS OF PEO/MgO COMPOSITE PREPARED VIA EXTRUSION : bachelor thesis
No full textSvrha ovog rada bila je istražiti utjecaj dodatka magnezijevog oksida (MgO) na strukturu poli(etilen-oksida) (PEO). U tu svrhu su pripremljeni uzorci kompozita PEO/MgO različitih sastava na laboratorijskom ekstruderu, pri optimalnim uvjetima ekstrudiranja kako bi se izbjegla toplinska razgradnja. Primjenom infracrvene spektroskopije s Fourierovom transformacijom analizirani su uzorci kako bi se utvrdile moguće interakcije između komponenti. Potvrđeno je postojanje slabih interakcija koje su rezultat nastalih vodikovih veza u istraživanim kompozitima.The main goal of this work was to investigate the effect of magnesium oxide (MgO) addition on the structure of poly(ethylene oxide) (PEO). For this purpose, composite samples of different compositions were prepared on a laboratory extruder, under optimal extrusion conditions to avoid thermal degradation. Subsequently, the samples were analyzed using Fourier-transform infrared spectroscopy to determine the possible interactions between the components. As a result of hydrogen bond in the investigated composites, weak interactions were determined
INFLUENCE OF SBT IMPELLER DIAMETER ON GRANULOMETRIC PROPERTIES OF THE FINAL PRODUCT OF BATCH SONOCRYSTALLIZATION OF BORAX : bachelor thesis
No full textU radu je ispitan utjecaj promjera SBT miješala na granulometrijska svojstva kristala boraksa dobivenih šaržnom kristalizacijom s ultrazvučnim djelovanjem i istovremenim mehaničkim miješanjem. Kristalizacija se provodila postupkom kontroliranog hlađenja matične otopine brzinom od 6 °C h -1 pri amplitudi i pulsu ultrazvučnog djelovanja od 20%. Kako bi se sagledao utjecaj promjera SBT miješala na granulometrijska svojstva dobivenih kristala, ispitivanja su se provodila s tri različita promjera SBT miješala (D/d T = 0,43; 0,53; 0,63), pri čemu su brzine vrtnje tih miješala odgovarale minimalnoj brzini potrebnoj za postizanje stanja potpune suspenzije (N = N JS ). Granulometrijska analiza finalnog produkta izvršena je metodom laserske difrakcije. Rezultati analiza ukazuju na monomodalnu raspodjelu veličina dobivenih kristala boraksa za sva tri primijenjena promjera SBT miješala. Povećanjem promjera SBT miješala raste udio finijih frakcija u uzorku, te se općenito smanjuju vrijednosti medijana raspodjele i srednjeg volumnog promjera kristala. Smanjenje veličine kristala direktno se odražava na povećanje njihove specifične površine. Vrijednosti širine raspodjele i koeficijenta varijacije ukazuju na užu širinu raspodjele pri korištenju manjeg promjera SBT miješala. Dobiveni rezultati u uskoj su vezi s hidrodinamičkim uvjetima u kristalizatoru koje generiraju korištena miješala, kao i načinom djelovanja ultrazvuka.The study examined the influence of the SBT impeller diameter on the granulometric properties of borax crystals obtained through batch crystallization with simultaneous ultrasonic irradiation and mechanical mixing. The crystallization was conducted by cooling the mother solution at a rate of 6 °C h -1 in the crystallizer with an ultrasonic irradiation amplitude and pulse of 20%. To examine the influence of the SBT impeller diameter on the granulometric properties of borax crystals, tests were conducted with three different impeller diameters (D/d T = 0.43, 0.53, 0.63). The impeller speed corresponded to the minimum speed required to achieve complete suspension (N = N JS ). The granulometric analysis of the final product was performed using the laser diffraction method. The results indicate a monomodal distribution of borax crystal sizes for all three applied SBT impeller diameters. As the SBT impeller diameter increased, the proportion of finer fractions increased, and overall the median and mean volume diameter of borax crystals decreased. The reduction in the size of the obtained crystals reflects an increase in the specific surface area of the crystals. The distribution width and coefficient of variation values indicate the narrower distribution width for the smaller applied SBT impeller diameter. The obtained results are closely related to the hydrodynamic conditions in the crystallizer generated by the used impellers, as well as the mode of ultrasonic irradiation
Phytoremediation of heavy metals : bachelor thesis
No full textZagađenje okoliša teškim metalima predstavlja ozbiljan i rastući problem u svijetu zbog povećane industrijalizacije i poremećaja prirodnih biogeokemijskih ciklusa. Teški metali, za razliku od organskih tvari, nisu biorazgradivi i akumuliraju se u okolini što predstavlja rizik za okoliš i zdravlje svih živih bića. Kakvoća tla izravno utječe na očuvanje bioraznolikosti, održivost ekosustava, a samim time i na ljudski razvoj, zdravlje i sigurnost. Remedijacija tla onečišćenog kompleksnim mješavinama organskih tvari i teških metala predstavlja jedan je od najvećih izazova obnavljanja okoliša. Do sada su se za tu svrhu primjenjivali različiti fizikalni, kemijski i biološki pristupi, ali primijenjene sanacijske metode prate veliki nedostatci poput visokih troškova, intenzivnog rada, nepovratnih promjena svojstava tla i narušavanja izvorne mikroflore tla. Jedan od novijih pristupa sanaciji tla onečišćenog teškim metalima je fitoremedijacija koja predstavlja skup tehnika koje upotrebom različitih biljnih vrsta rješavaju problem onečišćenja teškim metalima. Predstavlja skup tehnika koje upotrebljavaju biljke, njihove enzime i prisutne mikroorganizme iz zone korijenja za izolaciju, transport, detoksikaciju i mineralizaciju ksenobiotika, čime se smanjuje njihova koncentracija, pokretljivost ili toksični učinci. Sastoji se od fitoekstrakcije, fitostabilizacije, fitovolatizacije, fitorazgradnje, fitodesalinacije i rizorazgradnje, a sve te tehnike imaju velik potencijal za nedestruktivnu remedijaciju različitih vrsta tla.Heavy metal pollution is a serious and growing problem in the world due to increased industrialization and disruption of natural biogeochemical cycles. Heavy metals, unlike organic matter, are not biodegradable and accumulate in the environment which poses a risk to the environment and the health of all living things. Soil quality directly affects the conservation of biodiversity, the sustainability of ecosystems, and thus human development, health and safety. Remediation of soil contaminated with complex mixtures of organic matter and heavy metals is one of the greatest challenges of environmental renewal. So far, different physical, chemical and biological approaches have been applied for this purpose, but the applied remediation methods are accompanied by major shortcomings such as high costs, intensive work, irreversible changes in soil properties and disruption of the original soil microflora. One of the newer approaches to the remediation of soil contaminated with heavy metals is phytoremediation, which represents a set of techniques that use different plant species to solve the problem of heavy metal pollution. It is a set of techniques that use plants, their enzymes and present microorganisms from the root zone to isolate, transport, detoxify and mineralize xenobiotics, thereby reducing their concentration, mobility or toxic effects. It consists of phytoextraction, phytostabilization, phytovolatization, phytodegradation, phytodesalination and rhizodegradation, and all these techniques have a great potential for non-destructive remediation of different soil types
Liquid alternative fuels : bachelor thesis
No full textKapljevita alternativna goriva (metanol, etanol, biodizel) mogu biti rješenje za sve veće energetske zahtjeve rastuće svjetske populacije kao i način smanjenja zagađenja okoliša. Metanol je bezbojna i lako hlapljiva tekućina te najjednostavniji alkohol. Sintezni plin predstavlja glavnu sirovinu za proizvodnju metanola adijabatskim i izotermnim postupkom. Katalitičko hidrogeniranje atmosferskog CO 2 je obećavajući način proizvodnje metanola. Metanol se lako skladišti i transportira, jeftin je i ima ga u izobilju, ima veći oktanski broj i latentnu toplinu isparavanja od benzina te pri izgaranju ne stvara dim, čađu ili čestice. Metanol se može koristiti i u gorivnim člancima te za proizvodnju visokooktanskog benzina. Etanol je hlapljiva, lako zapaljiva i bezbojna kapljevina, proizvodi se pretežito fermentacijom biomase, a manjim dijelom adicijom vode na eten. Bioetanol se može proizvesti iz šećera, škrobnih i lignoceluloznih materijala. Najčešća upotreba etanola je kao gorivo i dodatak gorivu zbog visokog oktanskog broja, sigurnog transporta i skladištenja. Biodizel je mono-alkilni ester masnih kiselina najčešće dobiven iz biljnih ulja i ulja iz algi. Biorazgradljiv je i nije otrovan. Glavna primjena je kao dodatak ili zamjena mineralnog dizela zbog dobrih svojstava podmazivanja i smanjenja količine štetnih ispušnih plinova.Liquid alternative fuels (mehtanol, ethanol, biodiesel) can be the solution to the growing energy demands of a growing world population as well as a way to reduce environmental pollution. Methanol is a colorless, volatile liquid and the simplest alcohol. Synthetic gas is the main raw material for methanol production by adiabatic and isothermal processes. Catalytic hydrogenation of atmospheric CO 2 is a promising way to produce methanol. Methanol is easy to store and transport, has a higher octane number and latent heat of vaporization than gasoline, and does not produce smoke, soot or particles during combustion. Methanol can also be used in fuel cells and for the production of high-octane gasoline. Ethanol is a volatile, highly flammable and colorless liquid, produced mainly by biomass fermentation, and to a lesser extent by the addition of water to ethene. Bioethanol can be produced from sugar, starch and lignocellulosic materials. The most common use of ethanol is as fuel and fuel additive due to its high octane number, safe transport and storage. Biodiesel is a mono-alkyl ester of fatty acids most commonly derived from vegetable oils and algae oils. It is biodegradable and non-toxic. The main application is as an additive or replacement of mineral diesel due to its good lubricating properties and reduced emission of harmful gases
Volatile compounds of ailanthus honey : master thesis
No full textU ovom su radu analizirani hlapljivi spojevi meda od pajasena. Hlapljivi spojevi meda izolirani su metodom mikroekstrakcije vršnih para na krutoj fazi (HS-SPME) koristeći tri vlakna (ružišasto vlakno, sivo vlakno i bijelo vlakno). Uzorci hlapljivih spojeva su analizirani vezanim sustavom plinska kromatografija- masena spektrometrija (GC-MS). Kao dominantni spojevi identificirani su: hotrienol, heksadekan-1-ol, trikosan, tetrakosan, dokosan i terpeni, pogotov derivati linaloola: trans-linalool oksid, cis-linalool oksid i izomer adehida jorgovana.In this paper, the volatile compounds of ailanthus honey were analyzed. Volatile honey compounds were isolated by headspace-solid phase microextraction (HS-SPME) using three fibers (pink fiber, gray fiber and white fiber). Samples of volatile compounds were analyzed by gas chromatography-mass spectrometry (GC-MS) method. The dominant compounds were identified as: hotrienol, hexadecan-1-ol, tricosane, tetracosane, docosane and terpenes, especially linalool derivatives: trans-linalool oxide, cis-linalool oxide and isomer of lilac aldehyde