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Primjena turbidimetrije za određivanje početka nukleacije u procesu šaržne kristalizacije : završni rad
No full textU radu je ispitana mogućnost primjene turbidimetrijske metode za određivanje početka nukleacije u procesu šaržne kristalizacije boraksa koja se provodi postupkom kontroliranog hlađenja. Nukleacija uzrokuje promjenu fizikalnih karakteristika sustava, između ostalog i zamućenje matične otopine. Upravo pojava zamućenja upućuje na mogućnost primjene turbidimetrijske metode za određivanje početka nukleacije tj. maksimalnog stupnja prezasićenosti sustava. Početak nukleacije u ispitivanom sustavu određen je i potenciometrijskom metodom. Ispitivanja su se provodila u kristalizatoru laboratorijskog mjerila volumena 2.14 dm 3 u kojem se matična otopina miješala uporabom turbinskog miješala s četiri ravne lopatice nagnute pod kutom od 45° (tzv. 4-PTD miješala). Pri svim mjerenjima brzina hlađenja zasićene otopine iznosila je b = 6 o C/h, dok je korišteno turbinsko miješalo imalo brzinu vrtnje od N = 300 o./min. Kako bi se dobio uvid o osjetljivosti primijenjenih metoda, ispitivanja su se provodila u otopinama boraksa zasićenima na različitim temperaturama, ali koje su bile hlađene istom brzinom od 6 °C/h. Početak nukleacije u sustavu je određivan i potenciometrijskom metodom. Rezultati usporedbe izvršenih mjerenja ukazali su na vrlo visoku osjetljivost turbidimetrijske metode pri određivanju ovog kristalizacijskog parametra koji određuje kinetiku cjelokupnog procesa.The purpose of this research was to examine the applicability of turbidimetric method for determination of nucleation in the process of batch cooling crystallization of borax. Nucleation causes the changes of physical properties of the system, among the others, changes in mother liquor clarity. In fact, this phenomenon potentially enables the application of a turbidimetric method for detection the nucleation commencement within the system. i.e. the maximum degree of system supersaturation. The onset of nucleation in the examined system is determined by the potentiometric method as well. All experiments were carried out in the stirred batch cooling crystallizer with the volume of 2.14 dm 3 . The mother liquor was stirred by axial four bladed pitched blade turbine (4-PBT). In all experiments saturated solutions were cooled down at constant rate of 6 °C/h while the impeller speed was 300 rpm. In order to obtain insigt into the sensitivity of the applied methods, the examination were carried out in borax solutions saturated at different temperatures and cooled at the same rate of 6 °C/h. By compering the results of the mesurments , the high sensitivity of the urbidimetric method is confirmed in determination of metastable zone width, which is parameter that affects kinectics of overall crystallization process
Development of carbon-based DNA-biosensors for the purpose of electrochemical characterization of bisphenol-A : diploma thesis
No full textU ovom radu ispitivano je elektrokemijsko ponašanje elektrode od ugljikove paste te dijamantne elektrode dopirane borom u svrhu elektrokemijskog određivanja bisfenola A. Ove elektrode su zbog svoje pristupačnosti i osjetljivosti vrlo pogodni kandidati za (bio)senzore. Mjerenja su vršena u otopini fosfatnog pufera (0,1 M) pri pH 7. Elektroanalitičko određivanje bisfenola A vršeno je uporabom diferencijalne pulsne voltametrije, DPV (engl. differential pulse voltammetry). Elektroda od ugljikove paste pokazala je bolji odziv. Iako obje elektrode literaturno posjeduju veliki potencijal za uporabu kao DNA-biosenzori, pokazano je da dobiveni rezultati znatno ovise o tretmanu kojem je površina elektrode podlegla prije uporabe. Isto tako, ističe se važnost modifikacije aktivne površine elektrode, odnosno same imobilizacije DNA u kontekstu utjecaja na dobivene rezultate.In the present paper the electrochemical behavior of carbon paste and boron doped diamond electrode was tested for purpose of bisphenol A electrochemical determination. Since electrodes like these are very affordable and since they possess great sensitivity, they are very suitable (bio)sensor candidates. The measurements were carried out in the phosphate buffer solution (0,1M) at pH 7. The electroanalytical determination of bisphenol A was done using differential pulse voltammetry. The carbon paste electrode exhibited better response. Even though both electrodes possess a great potential for being used as DNA-biosensors, it was shown that obtained results depend on the treatment the electrode underwent before the utilization. Also, the importance of the surface area modification, as well as the immobilization of DNA was accentuated in the context of the influence they have on the obtained results
Determination of metastable zone width of borax in a batch cooling crystallizer using different techniques : diploma thesis
No full textU ovom radu provedena je kristalizacija dinatrijevog tetraborata dekahidrata (boraksa) šaržnim postupkom uz kontinuirano hlađenje matične otopine. Cilj rada je bio odrediti širinu metastabilne zone boraksa različitim metodama: vizualnom, potenciometrijskom i turbidimetrijskom, te ispitati mogućnost njihove primjene i njihovu osjetljivost pri provedbi šaržne kristalizacije. Radi što potpunije usporedbe primijenjenih metoda, određivanje navedenog kristalizacijskog parametra, kao i brzine nukleacije, izvodilo se pri pet različitih temperatura zasićenja matične otopine boraksa. Ispitivanja su se provodila u kristalizatoru laboratorijskog mjerila volumena 2.14 dm 3 u kojem se matična otopina hladila brzinom od 6 °C/h. Analizom dobivenih rezultata uviđa se da sve primijenjene metode omogućuju određivanje početka nukleacije boraksa u navedenom procesu. Najosjetljivijom se ipak pokazala turbidimetrijska metoda pogotovo pri nižim temperaturama zasićenja matične otopine. Ta metoda je pokazala izrazitu osjetljivost i visoku reproducibilnost rezultata, a mogućnost njene primjene u pogonskim uvjetima daje joj dodatnu prednost u odnosu na ostale korištene tehnike.In this research the batch cooling crystallization of the disodium tetraborate decahydrate (borax) was performed and analysed. The aim of the work was to determine the metastable zone width of borax by different techniques: visual, potentiometric and turbidimetric with the purpose of examine the possibility of their application and analyse their sensitivity. For the fullest comparison of the applied methods, the experiments were performed at five different saturation temperatures of the borax mother liquor. All experiments were carried out in the stirred batch cooling crystallizer with the volume of 2.14 dm 3 . In all experiments the mother liquor, that is the saturated solutions were cooled down at constant rate of 6 °C/h. Experimental results have shown that the onset of nucleation, that is the metastable zone width of borax in the process of batch cooling crystallization can be determined by all applied techniques. Turbidimetric method has been shown as the most sensitive, especially at lower saturation temperature of the mother liquor.This method can be considered as very objective and the reproducibility of its the results is extremely high. Possibility of its application in industrial and/or semi-industrial operating conditions gives it an additional advantage over the other applied techniques
Equilibrium adsorption of cobalt and copper ions on spent coffee ground : diploma thesis
No full textU ovom diplomskom radu ispitivana je ravnotežna adsorpcija iona teškog metala (kobalta ili bakra) iz odgovarajućih vodenih otopina na talogu kave. Adsorpcija je provedena u šaržnom reaktoru, pri različitim početnim koncentracijama otopina iona teškog metala, stalnoj temperaturi od 308 K, brzini miješanja od 200 okr min-1, u trajanju eksperimenta od 96 h. Ispitan je utjecaj ravnotežnih koncentracija iona teškog metala (kobalta ili bakra) na ravnotežnu količinu adsorbiranog iona teškog metala te je nađeno da ona raste s povećanjem ravnotežne koncentracije iona teškog metala u otopini do postizanja maksimalnog kapaciteta adsorpcije, nakon čega se značajno ne mijenja (kod kobalta kao teškog metala) ili ostaje stalna (kod adsorpcije bakrovih iona). Maksimalni eksperimentalni kapacitet adsorpcije za zadane uvjete rada za adsorpciju kobaltovih iona iznosi qmax = 0,396 mmol g-1, dok za bakar iznosi qmax = 0,164 mmol g-1. Učinkovitost adsorpcije iona teškog metala na talogu kave opada s porastom početne koncentracije iona teškog metala u otopini, što se može pripisati zasićenju dostupnih mjesta za adsorpciju na talogu kave. Dobiveni eksperimentalni podatci testirani su Langmuirovom, 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 χ2-test, može se zaključiti da najbolje slaganje s eksperimentalnim podatcima pokazuje Langmuirov model za adsorpciju kobaltovih iona dok za adsorpciju bakrovih iona najbolje slaganje pokazuju Tothov i Sipsov model.In this diploma thesis, the equilibrium adsorption of heavy metal ions (cobalt or copper) from the corresponding aqueous solution on the spent coffee ground was investigated. Adsorption was carried out in a batch reactor at different initial concentrations of heavy metal ions, at a constant temperature of 308 K, a stirring speed of 200 rpm min-1 for 96 h. The impact of heavy metal equilibrium concentrations (cobalt or copper) on the equilibrium amount of heavy metal adsorbed was investigated and it was found to increase with the equilibrium concentration of heavy metal in the solution until it achieves maximum adsorption capacity, after which it does not change significantly (in cobalt as heavy metal) or remains constant (in the case of copper ion adsorption). The maximum experimental adsorption capacity for experimental conditions used for the cobalt ion adsorption was qmax = 0.396 mmol g-1, while for copper was qmax = 0.164 mmol g-1. The adsorption efficiency of heavy metal ions on the spent coffee grounds decreases with the initial concentration of heavy metal ions in the solution, which can be attributed to the saturation of the available adsorption sites on the spent coffee grounds. The experimental data obtained were tested on Langmuir, Toth, Redlich-Peterson and Sips isotherms. By estimating the quality of adsorption models with experimental data, by comparing calculated maximum adsorption capacity values with experimentally obtained, and comparing statistical parameters for RMSE and χ2-test, it can be concluded that the best agreement with the experimental data showed Langmuir isotherm for the adsorption of cobalt ions while for the adsorption of copper ions the best agreement showed Toth and Sips isotherms
Effect of blade angle of PBT impeller on the ion exchange : bachelor thesis
No full textU prvom dijelu ovog rada ispitan je utjecaj nagiba lopatica PBT miješala na postizanje stanje potpune suspenzije zeolita 13X. Na osnovu rezultata utvrđeno je da se povećanjem nagiba lopatica PBT miješala, sa 30° na 70° smanjuje kritična brzina vrtnje miješala N JS kao i vrijednost zakretnog momenta. Vrijednosti zakretnog momenta direktna su posljedica kritične brzine vrtnje miješala, N JS . Osim toga u ovom radu se primjenom Taguchijeve metode ispitao utjecaj temperature suspenzije, nagiba lopatica miješala, veličine čestica zeolita i brzine okretaja miješala na ionsku izmjenu bakra na zeolitu 13X. Zadatak rada je bio pronaći optimalne vrijednosti ispitivanih procesnih varijabli, korištenjem Taguchijeve metode, pri kojima se vezalo najviše bakra na zeolit. Količina bakra se računala iz razlike početnih i konačnih koncentracija bakrovih iona u suspenziji. Konačne koncentracije bakrovih iona su određene spektrofotometrom. Taguchijevom metodom utvrđen je utjecaj ispitivanih procesnih varijabli na proces. Naime, rezultati su pokazali da se najveća količina bakra veže na zeolit pri najvećoj ispitivanoj temperaturi (33°C), te pri najvećem ispitivanom nagibu lopatica (70°). Utjecaj veličine čestica i brzine vrtnje miješala na proces je zanemariv budući da se kod korištenih veličina čestica može zanemariti utjecaj unutarfazne difuzije, a brzina miješanja je dovoljno velika da se može zanemariti utjecaj međufazne difuzije. Nakon izračuna optimalnih vrijednosti ispitivanih procesnih varijabli, provedena su kinetička ispitivanja te su dobiveni eksperimentalni podaci uspoređeni s Ritchievim kinetičkim modelom s obzirom da se isti koristi za modeliranje izmjene bakra na zeolitu.In the first part of this paper, the effect of blade angle of PBT impeller on the state of complete suspension of zeolite 13X was examined. It is evident that by increasing the angle of the PBT impeller, from 30° to 70°, the impeller speed decrease as well as the torque value. Torque values are directly related to the critical impeller speed, N JS . Other than that, in this paper, the effect of the suspension temperature, blade angle of PBT impeller, zeolite particle size and impeller speed on copper exchange on zeolite 13X was studied using Taguchi method. The aim of this part of the work was to find the optimal value of process parameters studied for which the maximum amount of copper on the zeolite 13X was exchanged. The amount of copper is calculated from the difference between the initial and final concentrations of the copper ions in the suspension. The final concentrations of the copper ions are determined by the spectrophotometer. Using the Taguchi method the effects of process parameters on the process was found. Namely, the results show that the maximum amount of copper exchange on zeolite at the highest temperature (33°C), and the highest blade angle (70°) investigated. The influence of particle size and impeller speed is negligible in the process because the particles are small enough to avoid the effect of the intraparticle diffusion and the impeller speed is large enough to avoid the effect the film diffusion. After the calculation of optimal value of process conditions studied, kinetic studies were performed as well and the experimental data obtained were compared with the Ritchi kinetic model
Garden candytuft (Iberis umbellata L.) as a potential copper hyperaccumulator : diploma thesis
No full textU ovom diplomskom radu ispitan je utjecaj zalijevanja štitaste ognjice (Iberis umbellata L.) otopinom teškog metala (bakra), kao i utjecaj raznih dodatka humusu na sposobnost hiperakumulacije bakra u štitastoj ognjici. Vizualnom karakterizacijom štitaste ognjice uočilo se kako niti jedna štitasta ognjica, neovisno u kojem humusu je uzgajana ili s čime je zalijevana, nije pokazala vidljive znakove fitotoksičnosti. Najviša koncentracija bakra u organima štitaste ognjice izmjerena je u uzorcima biljke koja je zalijevana otopinom teškog metala CuSO4∙5H2O (731,61 µg g-1), dok je najniža koncentracija izmjerena u uzorku štitaste ognjice koja je zalijevana vodovodnom vodom, a uzgajana u humusu bez dodataka (7,07 µg g-1). U ovisnosti vrste sorbensa u humusu mijenja se i sadržaj bakra u biljci pa je tako najviša koncentracija bakra u organima biljke detektirana u štitastoj ognjici uzgajanoj u humusu s dodatkom ljuskica jaja (69,78 µg g-1), a najniža u humusu s dodatkom zeolita NaX (37,14 µg g-1). S obzirom da je štitasta ognjica u periodu od četrdeset dana zalijevanja vodenom otopinom bakra usvojila visoku koncentraciju bakra u svojim organima (731,61 µg g-1) bez vidljivih znakova fitotoksičnosti može se zaključiti kako se radi o hipertolerantnoj biljci u odnosu na bakar kao teški metal. Daljnjim istraživanjima štitasta ognjica bi se trebala duže tretirati vodenom otopinom bakra kako bi se mogla dokazati hiperakumulacija bakra kao teškog metala u štitastoj ognjici.In this diploma thesis, the influence of watering of the garden candytuft (Iberis umbellata L.) with solution of heavy metal (copper), as well as the influence of various humus additions to the ability of copper hyperaccumulation in garden candytuft was examined. By visual characterization of the garden candytuft, it was noticed that the garden candytuft, independently in which humus the plant was growing or with what it was watered, did not show any visible signs of phytotoxicity. The highest concentration of copper in the garden candytuft was measured in the samples of the plant that was watered with a solution of heavy metal CuSO4∙5H2O (731.61 μg g-1), while the lowest concentration was measured in the sample of the garden candytuft which was watered with water and grown in humus without additives (7.07 μg g-1). Depending on the type of sorbent added in humus, the copper content in the plant also varied. The highest concentration of copper in the plant organs was detected in the garden candytuft grown in humus with the addition of egg shells (69.78 μg g-1), and the lowest in humus with the addition of zeolite NaX (37.14 μg g-1). Given that the garden candytuft in a forty-day period of watering with an aqueous copper solution has taken up a high concentration of copper in its organs (731.61 μg g-1) with no visible signs of phytotoxicity it can be concluded that it is a hypertolerant plant for copper as a heavy metal. In further investigations the garden candytuft should be treated longer with aqueous copper solution to prove the hyperaccumulation of copper as a heavy metal in the garden candytuft
Distribution of heavy metals in perennial wall-rocket (Diplotaxis tenuifolia L. DC.) : bachelor thesis
No full textU ovom završnom radu određene su koncentracije odabranih teških metala (cink, željezo, mangan, nikal, bakar, kadmij, olovo i aluminij) u uskolisnom dvoredcu (Diplotaxis tenuifolia L. DC.) koji je sabran u rujnu 2017., na polju iza zgrade Kemijsko-tehnološkog fakulteta. Uskolisni dvoredac je podijeljen na dva dijela: podzemni (korijen) i nadzemni (listovi, cvijet, stabljika). Koncentracije teških metala u otopinama uskolisnog dvoredca su određene pomoću spektrometrije masa s induktivno spregnutom plazmom (ICP-MS). Na temelju izmjerenih vrijednosti može se uočiti da su koncentracije kadmija, nikla, aluminija, željeza i mangana više u podzemnim dijelovima biljke, dok cink, olovo i bakar pokazuju više koncentracije u nadzemnim dijelovima biljke što je posljedica translokacije iz korijena. Toksični kadmij pokazuje najnižu izmjerenu koncentraciju (0,053 µg g-1) u nadzemnom i dvostruko višu koncentraciju (0,112 µg g-1) u podzemnom dijelu biljke i nalazi se u okviru dopuštenih koncentracija. Najveću koncentraciju u uskolisnom dvoredcu pokazuje aluminij u podzemnom dijelu 245,521 µg g-1, a s obzirom da biljka nije pokazala nikakve znakove fitotoksičnosti moglo bi se zaključiti kako se radi o hipertolerantnoj biljci, ako ne i o hiperakumulatoru, što je potrebno dodatno istražiti.In this bachelor thesis, concentrations of selected heavy metals (zinc, iron, manganese, nickel, copper, cadmium, lead and aluminum) were determinated in perennial wall-rocket (Diplotaxis tenuifolia L. DC.) which was collected in September 2017, on the field behind the Faculty of Chemistry and Technology building. The perennial wall-rocket was divided into two parts: the underground part (root) and aerial part (leaves, flower, stem). Concentrations of heavy metals in solutions of the perennial wall-rocket were determinated by inductively coupled plasma mass spectrometry (ICP-MS). Based on the values obtained it can be noticed that concentrations of cadmium, nickel, aluminum, iron and manganese were higher in the underground part, while zinc, lead and copper showed higher concentrations in the aerial parts of the plant resulting from root translocation. Toxic cadmium showed the lowest measured concentration in the aerial part (0.053 μg g-1) and twice the higher concentration in the underground part of the plant (0.112 μg g-1) and is within the permissible concentrations. The highest concentration of 245.521 μg g-1 was measured for aluminum in the underground part of the perennial wall-rocket, and given that the plant did not show any signs of phytotoxicity it could be concluded that it may be a hypertolerant plant, if not the hypercumulator, which should be further investigated
Microwave-assisted synthesis of phenyl isothiocyanates : diploma thesis
No full textIzotiocijanati imaju izražen elektrofilni karakter zbog reaktivnosti centralnog ugljikovog atoma N=C=S koji brzo reagira s nukleofilima na bazi sumpora, dušika i kisika. Izotiocijanati se mogu dobiti iz različitih početnih materijala, a posebno izocijanida, alkena, aldehida ili organskih halogenida. Uglavnom se sintetiziraju aciliranjem amina upotrebom tiokarbonilnih reagensa poput tiofozgena ili kondenzacijom primarnog amina sa suviškom ugljikovog disulfida, u organskom otapalu koje je miješano s vodom, te praćeno dehidrosulfurizacijom s vodikovim peroksidom. U ovom radu prikazana je klasična sinteza fenil-izotiocijanata te mikrovalna sinteza fenil- izotiocijanata pri 37, 50 i 80 W. Produkt je dobiven reakcijom anilina sa ugljikovim disulfidom u vodenoj otopini kalijeva karbonata, pri čemu nastaje ditiokarbamatni međuprodukt koji je dodatno desulfuriran s cijanurskom kiselinom pri 0 °C. Klasičnom sintezom dobije se najmanja masa produkta od 4,44 g dok se mikrovalnom sintezom fenil-izotiocijanata pri 37 W dobije najveća masa od čak 6,16 g. U svim sintetiziranim produktima vidljiva je određena količina nečistoća koje bi trebalo ukloniti. Također, omjer količine nečistoća i ciljanog produkta se smanjuje u korist produkta s povećanjem snage mikrovalnog zračenja. Identifikacija sintetiziranih spojeva je izvršena spektroskopskim tehnikama kao što su: spektroskopija infracrvenog zračenja sa Fourierovom transformacijom (FTIR), plinska kromatografija sa plamenoionizacijskim detektorom (GC-FID), vezani sustav plinske kromatografije i spektrometar masa (GC-MS) te nuklearna magnetska rezonantna spektroskopija (NMR).Isothiocyanates have a strong electrophilic character due to the reactivity of the central carbon atom N=C=S that rapidly reacts with nucleophiles based on sulphur, nitrogen and oxygen. Isothiocyanates can be obtained from various initial materials, especially isocyanides, alkenes, aldehydes or organic halides. They are usually synthesized through the acylation process of amines with the use of thiocarbonyl reagents such as thiophosgene or through condensation of the primary amine with the surplus of carbon disulfide, in an organic solvent mixed with water and followed by the process of hydrodesulfurization using hydrogen peroxide. In this thesis the classic phenyl-isothiocyanate synthesis and the microwave phenyl- isothiocyanate synthesis at 37, 50 and 80 W are presented. The product was obtained through a reaction between aniline and carbon disulfide in an aqueous solution of potassium carbonate which produces a dithiocarbamate intermediate which was further desulfurized with cyanuric acid at 0 °C. By using the classic synthesis the smallest product mass of 4,44 g is obtained while by using the microwave phenyl- isothiocyanate synthesis at 37 W the largest mass of 6,16 g is obtained. In all synthesized products a certain amount of impurities was determined that should be removed. In addition, the amount of impurities to target product ratio is lowered in favour of the product as power of the microwave radiation increases. Identification of the synthesized compounds was conducted using spectroscopic techniques such as: Fourier-transform infrared spectroscopy (FTIR), gas chromatography with flame ionization detector (GC-FID), gas chromatography with mass spectrometer system (GC-MS) and nuclear magnetic resonance spectroscopy (NMR)
Chives (Allium schoenoprasum L.) as a potential lead, nickel and copper hyperaccumulator : diploma thesis
No full textU ovom diplomskom radu određene su koncentracije odabranih teških metala (olova, nikla i bakra) analizom otopina vlasca (Allium schoenoprasum L.) spektrometrijom masa s induktivno spregnutom plazmom (HR ICP-MS). Uočava se da je kod svake biljke koja je tretirana odgovarajućom vodenom otopinom teškog metala izmjerena najviša koncentracija tog metala u dvadesetom danu tretiranja nakon kojeg koncentracije počinju opadati. Vlasac tretiran vodenim otopinama olova i nikla počinje pokazivati znakove stresa tek nakon dvadesetog dana tretiranja odabranim otopinama, dok vlasac tretiran vodenom otopinom bakra pokazuje znakove stresa tijekom cijelog perioda tretiranja. Izmjerene koncentracije odabranih teških metala upućuju na zaključak kako je biljka vlasac hipertolerantna biljka s obzirom na usvajanje nikla, a moguće i na usvajanje bakra, dok izmjerene koncentracije za olovo govore kako bi se vlasac mogao razmatrati kao potencijalni hiperakumulator olova jer je u svim uzorcima koji su tretirani s vodenom otopinom olovljevog(II) nitrata njegova koncentracija viša od 1000 µg g-1.In this diploma thesis, concentrations of selected heavy metals (lead, nickel and copper) were determined by analyzing the chives solutions (Allium schoenoprasum L.) by inductively coupled plasma mass spectrometry (HR ICP-MS). It is evident that at each plant treated with appropriate heavy metal aqueous solution, the highest concentration of selected metal was measured in the twentieth day of treatment, after which the concentrations began to decrease. The chives treated with aqueous solutions of lead and nickel begins to show signs of stress only after twenty days of treatment with the selected solutions, while the treatment with copper solution showed signs of stress throughout the treatment. Measured concentrations of selected heavy metals suggest that the chives plant is a hypertolerant plant towards nickel and possibly copper. The measured lead concentrations indicate that the chives could be considered as a potential hyperaccumulator of lead because in all the samples treated with water solution of lead (II) nitrate, its concentration was higher than 1000 μg g-1
Preparation and characterization of PEO/ES composite : bachelor thesis
No full textSvrha ovog rada bila je pripremiti uzorke kompozita PEO/ES razliĉitih sastava na laboratorijskom ekstruderu pri ĉemu tijekom ekstrudiranja nije došlo do toplinske razgradnje. Pomoću infracrvene spektroskopije Fourierovom transformacijom istraživan je utjecaj mljevenih ljuskica jaja na strukturu poli(etilen-oksida) i postojanje možebitnih interakcija u kompozitima. Zakljuĉeno je kako dodatak mljevenih ljuskica jaja ne utjeĉe na strukturu PEO-a. Diferencijalna pretražna kalorimetrija primijenjena je kako bi se utvrdio utjecaj dodatka mljevenih ljuskica jaja na toplinska svojstva PEO-a. Dodatak mljevenih ljuskica jaja neznatno utjeĉe na vrijednosti staklišta, dok talište i kristalište PEO-a praktiĉki ostaju nepromijenjeni. Utjecaj dodatka mljevenih ljuskica jaja na toplinsku stabilnost PEO-a istraživana je primjenom termogravimetrijske analize. Može se zakljuĉiti da dodatak mljevenih ljuskica jaja neznatno utjeĉe na povećanje toplinske stabilnosti PEO-a u istraživanim kompozitima.The purpose of this study was to prepare samples of PEO/ES composites of different compositions on the laboratory extruder without thermal degradation. The effect of ground egg shells on the structure of poly(ethylene oxide) and the existence of possible interactions in composites were investigated by Fourier infrared spectroscopy. It was concluded that the addition of ground egg shells does not affect the structure of the PEO. Differential scanning calorimetry was applied to determine the effect of the addition of ground egg shells on the thermal properties of PEO. The addition of ground egg shells slightly affects the values of the glass, while the melting point and crystalization of PEO practically remained unchanged. The influence of the addition of ground egg shells on the termal stability of PEO was investigated using thermogravimetric analysis. It can be concluded that the addition of ground egg shells slightly affects the increase of the thermal stability of PEO in the investigated composites