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Mehanochemical synthesis and characterization of mixed metal oxides
No full textMehanokemijska sinteza je u današnje vrijeme veoma istraživana metoda zbog kraćeg vremena reakcija i mogućnosti korištenja slabo topljivih reaktanata. Uporaba otapala svedena je na minimum što doprinosi zaštiti okoliša. U ovom diplomskom radu sintetizirane su nanočestice složenih metalnih oksida kalcija i željeza metodom visokoenergetskog mljevenja unutar planetarnog kugličnog mlina. Dobiveni spojevi okarakterizirani su termogravimetrijskom analizom (TGA), infracrvenom spektroskopijom (FT-IR) i cikličkom voltametrijom (CV). Nadalje, promjenom različitih parametara mljevenja ispitani su uvjeti potrebni za nastajanje različitih struktura mješanih metalnih oksida kalcija i željeza. Također, opisan je i metodički dio na temu ''Zemnoalkalijski metali'' za 3. razred gimnazije koji sadrži pisanu pripremu za nastavni sat i radni listić. Predviđeno je frontalno predavanje koje završava zajedničkim ponavljanjem naučenog gradiva kroz pitanja na radnom listiću.Mehanochemical synthesis is nowadays a highly explored method for a shorter reaction time and the ability to use poorly soluble reactants. The use of solvents is reduced to a minimum that contributes to the protection of the environment. In this graduate thesis, nanoparticles of complex metal oxide of calcium and iron are synthesized by the method of high-energy grinding within a planetary ball mill. The obtained compounds are characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and cyclic voltammetry (CV) method. Furthermore, by changing the various parameters of milling, the conditions necessary for the formation of different structures of calcium and iron mixed metal oxides are examined. This thesis also contains a part with teaching methods on high school level including printed preparation for lesson "Earth Alkaline Metals" and corresponding working papers. A frontal lecture is envisaged that ends with a common repetition of the subject matter through questions on working paper
Investigation of the influence of nonionic surfactants on potentiometric determination of anionic surfactants using sensor with functionalized carbon nanotubes
No full textPojam tenzid je zajednički naziv za sve površinski aktivne tvari koje smanjuju površinsku napetost tekućine. Koriste se za pranje tekstila, kao emulgatori, omekšivači, sredstva za zaštitu od korozije, za dezinfekciju te imaju veliku primjenu i u kozmetici. Tenzidi su organske tvari te se sastoje od hidrofilnog i dugog ugljikovodičnog hidrofobnog dijela. U vodenoj otopini se u monomolekularnom sloju nakupljaju na granici faza pri čemu se hidrofilni dio orijentira prema vodenoj, a hidrofobni prema ne vodenoj fazi koja može biti masnoća, zrak ili druga organska nečistoća. Dijele se na temelju ionskog naboja na: anionske, kationske, neionske i amfolitske tenzide. Anionski tenzidi su najstarija i najzastupljenija skupina tenzida koja daje negativno nabijene površinski aktivne organske ione. Oni se vrlo lako raspršuju te se svrstavaju u visoko pjeneće površinski aktivne tvari. Neionski tenzidi nemaju nikakav naboj jer im se hidrofilni i hidrofobni dio molekule nalazi u ravnoteži. Potenciometrijska titracija je postupak koji je korišten za određivanje anionskog tenzida natrijevog dodecilsulfata (NaDDS), c = 4x M, uz dodatak neionskih tenzida Genapol T 080, Genapol T 110, Genapol T 150, Genapol T 250, Genapol T 500 i Genapol T 800, c = 1M. Senzor s čvrstim kontaktom i senzorskim materijalom koji je sadržavao funkcionalizirane višestjenčane ugljikove nanocjevčice i tetrafenilborat (MWCNT-TPB) je korišten za ispitivanje utjecaja kemijske prirode (broja etoksi grupa u molekuli) i koncentracije neionskih tenzida na određivanje anionskih tenzida.The term surfactant is a common name for all surface active substances that reduce the surface tension of the liquid. They are used for textile washing, as emulsifiers, softeners, corrosion protection agents, as disinfectants and also have great application in cosmetics. Surfactants are organic substances composed of hydrophilic and long hydrocarbon hydrophobic part. In the aqueous solution, the monomolecular layer accumulates at the phase boundary, whereby the hydrophilic portion is oriented toward the water and hydrophobic toward the non-aqueous phase which may be fat, air or other organic impurities. Due to their ionic charge they are divided into: anionic, cationic, nonionic and ampholytic surfactants. Anionic surfactants are the oldest and the most common group of surfactants that gives negatively charged surface-active organic ions. They are very easy to disperse and classified as high foaming surface-active substances. Nonionic surfactants have no charge because the hydrophilic and hydrophobic part of the molecule are in balance. Potentiometric titration is a method used to determine the anionic surfactant sodium dodecyl sulfate (NaDDS), c = 4x M, with the addition of nonionic surfactants Genapol T 080, Genapol T 110, Genapol T 150, Genapol T 250, Genapol T 500 and Genapol T 800, c = 1 M. The solid-state sensor with sensor material containing functionalized multiwalled carbon nanotubes and tetraphenilborate (MWCNT-TPB) was used to investigate the influence of the chemical nature (the number of ethoxy groups in the molecule) and the concentration of nonionic surfactants on anionic surfactants determination
Crown ethers, criptands and spherands
No full textKrunski eteri spadaju u skupinu spojeva koji se zovu makrociklički spojevi. Karakterizira ih prstenasta struktura koja se sastoji od niza eterskih jedinica između kojih se mogu nalaziti i heteroatomi poput dušika, sumpora, itd. Najviše su proučavani zbog sposobnosti stvaranja kompleksnih spojeva s raznim ionima metala. U takvom kompleksnom spoju ion metala je "gost" a krunski eter je "domaćin". Krunski eter određene veličine prstena favorizira kompleksiranje određenog iona metala. Ta pojava se naziva "templatnim efektom" te zahvaljujući njemu je moguće unaprijed odrediti strukturu kompleksnog spoja koja će savršeno odgovarati veličini metalnog iona. Primjer takvog domaćina su sferandi, koji su visokoselektivni prema ionima kalija te se zbog toga koriste u određivanju koncentracije kalija u krvi bolesnika. Budući da mogu kompleksirati i anione metala- alkalide, kriptandi su primjenu našli u ionskoj kromatografiji i anionskoj polimerizaciji.Crown ethers are a class of compounds that are called macrocycles. They have ring structure that consists of ether units which can alternate with heteroatoms such as nitrogen, sulphur, etc. The most studied property of crown ethers is their ability to complex various ions. In such compound metal ion is guest and crown ether is host. Crown ether of different ring size favor complexation with different metal ion. This concept is called "template effect" so one can design crown structure that will perfectly fit with metal ion. Example of this type of host are spherands that are highly selective toward potassium ions so they are turned into sensors for detection of K+ concentration in blood serum. Because of their ability to complex metal anions- alkalides cryptands are used in ion chromatography and anionic polymerization
Determination of colesterol in egg yolks by liquid chromatography
No full textKolesterol, jedan od glavnih sastojaka žumanjka jajeta, je po kemijskom sastavu lipid, točnije sterol. Smatra ga se esencijalnim jer mijenja fluidnost životinjskim staničnim membranama i preteča je steroidnih hormona. Nalazi se u hrani životinjskog podrijetla. Do visokih koncentracija kolesterola u organizmu dolazi pretjeranom konzumacijom hrane bogate kolesterolom. Uz to, na visoku koncentraciju utječe i sposobnost organizma da sam sintetizira kolesterol. Višak kolesterola se taloži na stjenkama arterija kao LDL-kolesterol (eng. low density cholesterol) tzv. "loš" kolesterol. Višak LDL-kolesterola uklanja HDL-kolesterol (eng. high density cholesterol) ili "dobar" kolesterol. Cilj ovog istraživanja bio je odrediti koncentraciju kolesterola u uzorcima žumanjka tekućinskom kromatografijom vrlo visoke razlučivosti (UPLC, eng. ultra performance liquid chromatography). Tekućinska kromatografija je, uz plinsku kromatografiju, najčešća metoda određivanja koncentracije kolesterola.Cholesterol, one of the main ingredient of an egg yolk, is by its chemical composition lipid, precisely sterol. It is considered to be essential because it changes fluidity of animal cell membranes and is forerunner for steroid hormones. Cholesterol can be found in food of animal origion. High concentrations of cholesterol in the body occur by excessive consuming cholesterol rich food. Cholesterol biosynthesis also affects on high concentration. Cholesterol excess deposits on artery walls as LDL-cholesterol (low density cholesterol) also known as "bad" cholesterol. The LDL-cholesterol excess is removed by HDL-cholesterol (high density cholesterol) or "good" cholesterol. The purpose of this research was to quantify the concentration of cholesterol in the egg yolk samples by UPLC (ultra performance liquid chromatography). Liquid chromatography, along with gas chromatography, is the most common method to quantify the concentration of cholesterol
Spectrophotometric and cromatographic determination of anions and cations in the drinking water samples
No full textU ovom su radu spektrofotometrijski i kromatografski proučavani pojedini kemijski parametri zdravstvene ispravnosti vode koji uključuju praćenje koncentracije kalcija, magnezija, kalija, natrija, željeza, mangana, fosfora, klora i fluora u uzorcima konzumne vode iz vodovodne mreže u Osijeku. Promatrana voda uzorkovana je na 6 različitih lokacija (tri blizu Vodovoda i tri udaljene od Vodovoda). Spektrofotometrijskom analizom određivane su koncentracija iona mangana i željeza. Drugi dio rada obuhvaćao je analizu konzumne vode ionskom kromatografijom. Određivale su se i uspoređivale koncentracije pojedinih aniona i kationa. Cilj istraživanja bio je praćenje koncentracije ispitivanih kationa i aniona u određenom vremenskom periodu te uspoređivanje dobivenih vrijednosti sa zakonskim regulativama. Kako bi se upotpunilo istraživanje, određivana je i pH vrijednost navedenih uzoraka. Dobiveni rezultati ispitivanih parametara nisu pokazali značajnija odstupanja od zakonom propisanih vrijednosti. Rezultati pokazuju veće koncentracije aniona i kationa kod udaljenih lokaliteta zbog starih vodovodnih cijevi kojima se distribuira voda.In this paper, certain chemical parameters of water quality which include monitoring of calcium, magnesium, potassium, sodium, iron, manganese, phosphorous, chlorine and fluorine concentration, were studied in the drinking water samples from the water supply network in Osijek by spectrophotometric and chromatographic analysis. The observed water was sampled in 6 different locations (three near the Water utility company and three away from the Water utility company). Spectrophotometric analysis was used to determine the concentration of manganese and iron ions. The second part of the work included analysis of drinking water with ionic chromatography. The concentrations of certain anions and cations were determined and compared. The aim of this research was to monitor the concentration of the investigated cations and anions in a given time period and compare the obtained values with the legal regulations. In order to complete the study, the pH value of the samples was also determined. The obtained results of the examined parameters did not show significant deviations from the statutory values. The results showed higher concentrations of anions and cations at locations far away from Water utility company because of the old water pipes used in water distribution
Fluorometric determination of selenium in eggs
No full textU ovom radu fluorimetrijski se određivao selenij u uzorcima jaja uz pomoć fluorescentnog markera 2,3-diaminonaftalena. Metoda se temelji na stvaranju kompleksa selenija s fluorescentnim markerom. Intenzitet fluorescencije nastalog kompleksa proporcionalan je koncentraciji selenija. Za razaranje uzoraka korištena je mikrovalna digestija. Kao otapala koristili su se cikloheksan, heptan i smjesa heptana i 3%-n-butil-acetata. Na temelju rezultata zaključeno je kako je najbolje otapalo za ekstrakciju kompleksa Se-DAN cikloheksan. Učinkovitost i točnost metode ispitani su određivanjem selenija u referentnom uzorku i metodom standardnog dodatka. Selenij je određen u tri domaća i tri kupovna jaja pri čemu nije bilo značajne razlike u sadržaju selenija između domaćih i kupovnih jaja.In this work, selenium was determined fluorimetrically in egg samples using the fluorescent marker 2,3-diaminonaphthalene. The method was based on the formation of a selenium complex with a fluorescent marker. The fluorescence intensity of the resulting complex was proportional to the selenium concentration. Microwave digestion was used to destroy the samples. Cyclohexane, heptane and a mixture of heptane and 3% n-butyl acetate were used as solvents. Based on the results, it was concluded that the best solvent for extraction of the Se-DAN complex was cyclohexane. The efficiency and accuracy of the method were tested by determining the selenium in the reference sample and using the standard addition method. Selenium was determined in three domestic and three purchase eggs, with no significant difference in selenium content between domestic and purchase eggs
Potentiometric investigation of new quaternary ammonium salts as sensor materials for anionic surfactants determination
No full textPet novosintetiziranih kvaternih amonijevih soli korišteno je za pripremu senzorskih materijala za potenciometrijsko određivanje anionskih tenzida. Svaka sol je otopljena uz dodatak natrijeva tetrafenilborata (NaTPB) pri ćemu su dobiveni bijeli talozi ionskih parova kvaternih amonijevih soli i NaTPB. Svi talozi su dodatno pročišćeni i izolirani te potom testirani kao senzorski materijali pri potenciometrijskoj titraciji anionskog tenzida. Kao titrans je korištena standardna otopina cetilpiridinijeva klorida (CPC) koncentracije c = 4· moldm, a kao analit otopina natrijeva dodecilsulfata (NaDDS) iste koncentracije. Nakon provedenih titracija i uspostavljanja ravnoteže u membrani, koristila se direktna potenciometrija za mjerenje odzivnih karakteristika senzora na anionske tenzide. Odziv senzora na NaDDS ispitan je u koncentracijskom području između 2,5 · i 5,0 · moldm u ultračistoj vodi. Na temelju rezultata mjerenja, određeni su nagib pravca (eng. slope) te granica detekcije i mjerno područje za svaki senzor. Prva elektroda, sa senzorskim materijalom 3-dioktadecil-1H-benzo[d]imidazol-3-ijev tetrafenilboratom (MJ1-TPB) je dala najbolje rezultate, nagib od -57,7 ± 0.8 mV/dekadi aktiviteta i granicu detekcije od 1,5 · moldm .Five new quaternary ammonium salts have been used to prepare sensor materials for potentiometric determination of anionic surfactants. Each salt was dissolved with sodium tetraphenylborate (NaTPB) addition and as a result, a white precipitates of ionic pairs of quaternary ammonium salts and NaTPB were formed. All the precipitates were then purified, isolated and tested as sensor materials for potentiometric titration of anionic surfactant. A standard solution of cetylpyridinium cloride (CPC, c = 4· moldm) was used as the titrant and sodium dodecylsulfate (NaDDS) solution at a same concentration was used as the analyte. After titrations and restoring equilibrium in the membrane, direct potentiometry was used to measure the response characteristics of each sensor to anionic surfactant. Sensor response to NaDDS was tested in concentration range between 2,5 · and 5,0 · moldm in ultra-pure water. Based on the results, slope, detection limit and useful concentration range for each sensor were determined. The best results were obtained using the first electrode, with 3-dioctadecyl-1H-benzo[d]imidazole-3-tetraphenylborate (MJ1-TPB) as sensor material: a slope of -57.7 ± 0.8 mV/decade of activity and the limit of detection of 1,5 · moldm
Examnation of the possibility of using eutectic solvents in quaternization reactions
No full textZbog problematike korištenja štetnih organskih otapala u sintetskim procesima, sve se veća pažnja posvećuje eutektičkim otapalima kao ekološki prihvatljivijom alternativom u odnosu na tradicionalna organska otapala, prvenstveno zbog svoje dostupnosti, biorazgradivosti, nehlapljivosti, stabilnosti i mogućnosti recikliranja. U ovom radu ispitana je mogućnost primjene eutektičkih otapala na bazi kolin-klorida (ChCl) u reakcijama kvaternizacije. Kvaternizacija je izvedena na nikotinamidu pomoću elektrofila 2-bromacetofenona. Posljednjih godina intenzivno se ispituje moguća sinteza kvaternih soli derivata piridina, uključujući kvaternih soli nikotinamida, te njihova primjena kao antibakterijska, antifungalna, antidotska i antikancerogena sredstva.Due to the problems regarding the usage of harmful organic solvents in the synthesis processes, increasing attention is being given to eutectic solvents as a environmentally acceptable alternative to the traditional organic solvents. This is primarily due to their availability, biodegradability, non-volatility, stability and recycling capabilities. In this thesis, the possibility of using eutectic solvents based on choline chloride (ChCl) in the quaternization reactions is investigated. Quaternization was performed on nicotinamide using 2-bromoacetophenone as na electrophile. In recent years, the possible synthesis of quaternary salts of pyridine derivatives, including quaternary salts of nicotinamide, and their use as antibacterial, antifungal, antidotic and anticancerogenic agents has been extensively investigated
Analysis photochemical pollution of the Southern Adriatic
No full textAtmosferski polutanti, nastali direktnom emisijom iz izvora ili kao posljedica djelovanja prekursora kao što su dušikovi oksidi i aerosoli, štetno utječu na zdravlje ljudi i kvalitetu biljnog i vodenog ekosustava. U ovom radu prikazani su rezultati mjerenja koncentracija dušikovih oksida, ozona te lebdećih čestica na području Južnog Jadrana. Korišteni su satni prosjeci koncentracija polutanata u razdoblju od 2015. - 2017. godine. Mjerna postaja je ruralna i pozadinska i smještena je na brdu Bosanka nedaleko od grada Dubrovnika (Žarkovica). Dobiveni podaci uspoređeni su s meteorološkim parametrima te su pokazali pozitivnu korelaciju mjerenih polutanata s temperaturom te negativnu s vlažnošću zraka. Za dušikove okside su bilježene maksimalne vrijednosti u rano jutarnjim te kasno popodnevnim satima što se može pripisati povećanom prometu. Karakteristična pojava za ozon je njegov izraženi dnevni hod s maksimalnim koncentracijama oko podneva kada su Sunčeva zračenja najjača. Visoke koncentracije lebdećih čestica bilježe se u ljetnim i zimskim mjesecima zbog povećanog prometa i koncentracija ljudi u vrijeme sezone te zimi zbog gorenja biomasa. U polarnim dijagramima se uočava da su povećane koncentracije polutanata povezane s sjeverozapadnim, sjeveroistočnim te jugoistočnim vjetrovima. U metodičkom dijelu diplomskog rada obrađena je nastavna jedinica "Kruženje ugljika u prirodi". Obradom nastavne jedini za 7. razred osnovne škole učenici su usvojili pojam atmosfere, fotosinteze te staničnog disanja kao glavnih procesa na Zemlji.The atmospheric pollutants, which appear after direct source emission, or as a consequence of precursor effects, such as nitrogen oxides and aerosols, have a significant harmful effect on human health and quality of floral and water eco-systems. In this thesis, the results of the taken measures of concentration of NOx, ozone, and particulate matter across South Dalmatia region have been compiled. Hourly averages of the pollutant concentrations have been taken as data since year 2015. until 2017. Measuring station is rural and is in hinterland on Bosanka hill, not very far away from Dubrovnik. The available data have been compared with the meteorological parameters and the results have shown positive correlation between the air temperature and negative correlation with air humidity. As for NOx concetrations, maximal values have been observed in the early morning and late afternoon hours, which can possible be attributed to traffic rush hour. On the other hand, characteristic of the ozone is its daily oscillations - maximal concentration values are around noon, when the Sun radiation is also maximal. Relatively high concentrations of particulate matter are reported in the summer and winter months, presumably because of increase in traffic congestion and concentration of the people, or during winter, because of the burning of biomass. The polar diagrams show us, also, that increase in the concentration of the pollutants are connected with northwest, northeast, and southeast winds. In the methodical part of the thesis, the central topic was curricular unit "Nature carbon cycling". By disseminating this topic, the students have understood the term atmosphere, photosyntesis and cellular respiration as the major processes on Earth
Potentiometric characterization of indomethacin nanosuspension
No full textIndometacin je lijek koji posjeduje protuupalna, analgetska i antipiretska svojstva. Spada u skupinu nesteroidnih protuupalnih analgetika (NSAID). Farmakološki učinak indometacina je neselektivna inhibicija enzima ciklooksigenaze. Glavni tehnološki problem kod indometacina, kao i kod svih lijekova koji spadaju u BCS-II skupinu je slaba topljivost u vodi. Kako bi se poboljšala topljivost lijekova u vodi razvijene su mnoge farmaceutsko-tehnološke strategije izrade prikladnih ljekovitih oblika (kruta disperzija, emulzija, mikrokapsuliranje, itd.). Jedna od tih strategija je priprema nanokristala te izrada nanosuspenzija. U ovom radu provedena je priprema i pokušaj karakterizacije nanosuspenzije indometacina. Metode kojima se izvršila karakterizacija su: DLS, TEM i potenciometrijska titracija nanosuspenzije, s naglaskom na zadnju metodu. Prvi rezultati pokazali su očitu razliku između titracijskih krivulja, ali izračun površinskog suviška protona se nije mogao napraviti zbog neodvoljne koncetracije krute tvari i upitnog stanja pH elektrode koja je korištena pri potenciometrijskim titracijama.Indomethacin is a drug with anti-inflamatory, analgetic and anti-pyretic properties. Indomethacin is classified as non-steroidal anti-inflamatory drug (NSAID). Pharmacological effect of indomethacin is non-selective inhibition of cyclooxygenase enzyme. Main technological problem with indomethacin, as well as with all drugs from BCS-II Class is poor solubility in water. Many pharmaceutically-technological strategies have been developed in order to improve properties of drug solubility in water (solid dispersions, emulsions, microcapsules). In this paper, the preparation and attempt to characterize indomethacine nanosuspension was performed. Methods by which the characterization was performed were: DLS, TEM and potentiometric titration of nanosuspension, with an emphasis on the latter. The first results showed obvious difference between titration curves, but calculation of surface proton excess could not be made due to insufficient concentration of the solid and questionable state of pH electrode that was used in the potentiometric titrations