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Potentiometric sensors with the addition of magnetite and hematite nanoparticles for determination of iron(III) cations : diploma thesis
No full textU diplomskom radu ispitivao se odziv potenciometrijskih senzora s dodatkom nanočestica magnetita i hematita za određivanje željezovih(III) kationa pri pH = 1,00 i pH = 5,00 koristeći ionsko-selektivne membrane. Željeni odziv potenciometrijskog senzora treba pratiti nagib pravca prema zahtjevima Nernstove jednadžbe za trovalentne katione. Membrane su ispitivane na odziv prema željezovim(III) kationima u elektrokemijskoj ćeliji koristeći otopinu željezovog(III) sulfata i željezovog(III) nitrata kao izvora Fe 3+ s dodatkom kalijevog nitrata. Ispitivanja su provedena metodom slijednog razrjeđivanja. Iz dobivenih rezultata membrana PNF 1 eksperimentalno pokazuje dobar nagib kako u laboratorijski pripravljenoj otopini željezovog(III) nitrata tako i u standardnoj otopini Fe 3+ kationa. PNF 1 senzor stoga je dobar za kvalitativnu analizu, a za kvantitativnu analizu potrebno je provesti dodatne analize. Ostali senzori nisu pokazali zadovoljavajuće karakteristike u svrhu određivanja željeza.In the thesis was examined response of potentiometric sensors with the addition of magnetite and hematite nanoparticles for the determination of iron(III) cations at pH = 1.00 and pH = 5.00 using ion-selective membranes. The desired response of the potentiometric sensor should follow the slope of the direction according to the requirements of the Nernst equation for trivalent cations. Membranes were tested for response to iron(III) cations in an electrochemical cell using a solution of iron(III) sulfate and iron(III) nitrate as a source of Fe 3+ with the addition of potassium nitrate. The tests were performed by the sequential dilution method. From the obtained results, PNF1 membranes experimentally show a good slope both in the laboratory-prepared solution of iron(III) nitrate and in the standard solution of Fe 3+ cation. The PNF1 sensor is therefore good for qualitative analysis, and additional analyzes are needed for quantitative analysis. Other sensors did not show satisfactory characteristics for the purpose of determining iron
Qualitative and quantitative determination of vitamins B1, B2 and B6 using HPLC-DAD : bachelor thesis
No full textZavršni rad opisuje razvoj i optimizaciju te vrednovanje metode kvantitativnog i kvalitativnog određivanja vitamina B 1 , B 2 i B 6 u prahu i kapsulama pomoću tekućinske kromatografije visoke djelotvornost spregnute s detektorom s nizom dioda. U istraživanju je korišten radni standard vitamina B kompleksa od kojeg su pripravljene matične otopine korištene za optimizaciju metode određivanja vitamina B 1 , B 2 i B 6 pomoću tekućinskog kromatografa s DAD spektrom kao detektorom. Kao otapalo izbora za B kompleks izabrana je smjesa acetonitrila i ultračiste vode + 0,3% fosforne kiseline u omjeru 10:90. Stacionarna faza je kolona s C18 punilom. Ispitane značajke vrednovanja koje uključuju specifičnost, linearnost, točnost, preciznost, granicu određivanja i dokazivanja i robusnost dale su zadovoljavajuće vrijednosti. Tekućinska kromatografija visoke djelotvornosti spregnuta s detektorom s nizom dioda je prikladna tehnika za kvantitativno i kvalitativno određivanje vitamina B 1 , B 2 i B 6 u prahu i kapsulama. Razvijena metoda je vrednovana čime je osigurana njena prikladnost za određivanje vitamina B 1 , B 2 i B 6 .The bachelor thesis describes development, optimization and validation of the method for quantitative and qualitative determination of vitamina B 1 , B 2 i B 6 in powder and capsules by high performance liquid chromatography coupled to diode array detector. The study used a standard of vitamin B complex from which main solutions were used to optimize a method of determination vitamins B 1 , B 2 i B 6 using a liquid cromatograph with DAD spectrometry as detector. The solvent of choice for B complex was a mixture of acetonitrile and ultra-pure water + 0.3 % phosphoric acid in a ratio of 10:90. Stationary phase was column with C18 filler. Tested validation parameters including specificity, linearity, accuracy, precision, limit of quantification and detection, stability and robustness resulted with adequate values. High performance liquid chromatography coupled to a diode array detector is a suitable technique for the quantitative and qualitative determination of vitamin B 1 , B 2 i B 6 in powder and capsules. The method has been validated to ensure its suitability for the determination of vitamin B 1 , B 2 i B 6
Adsorption equilibrium of copper on sieved humus Potgrond H (T=298) : bachelor thesis
No full textIspitana je adsorpcija bakrovih iona na prosijanom humusu u ovisnosti o različitim početnim koncentracijama otopina bakrovih iona (2,876 mmol dm -3 , 5,415 mmol dm -3 , 8,200 mmol dm -3 , 11,091 mmol dm -3 te 14,524 mmol dm -3 ). Eksperiment je proveden pri stalnoj temperaturi od 298 K, brzini miješanja od 200 okr min -1 , u trajanju od 48 h te veličini čestica < 500 μm. Na temelju dobivenih rezultata može se zaključiti kako se količina adsorbiranih bakrovih iona (q e ) neznatno mijenja s porastom početne koncentracije bakrovih iona u otopini (c 0 ), a svoju maksimalnu vrijednost dostiže pri početnoj koncentraciji od 11,091 mmol dm -3 te iznosi q e = 0,265 mmol g -1 za uvjete pri kojima je eksperiment proveden. Učinkovitost adsorpcije bakrovih iona dostiže svoju maksimalnu vrijednost za najnižu odabranu početnu koncentraciju od 2,876 mmol dm -3 te iznosi 42,330 % te nakon toga opada s porastom početne koncentracije bakrovih iona u otopini. Adsorpcija bakra na prosijanom humusu može se opisati Langmuirovim adsorpcijskim modelom (R 2 = 0,995). Usporedbom rezultata s rezultatima dobivenim kad je kao adsorbens korišten netretirani humus, pri istim eksperimentalnim uvjetima, može se zaključiti kako je proces adsorpcije bakra iz bakrovog(II) klorida dihidrata ipak bolje provesti na netretiranom humusu (q e = 0,272 mmol g -1 te učinkovitost adsorpcije 46,990 %).The adsorption of copper ions on sieved humus was studied depending on the different initial concentrations of copper ion solutions (2.876 mmol dm -3 , 5.415 mmol dm -3 , 8.200 mmol dm -3 , 11.091 mmol dm -3 , and 14.524 mmol dm -3 ). The experiment was carried out at a constant temperature of 298 K, stirring speed of 200 rpm, and a particle size of < 500 μm for 48 h. Based on the results obtained, it can be concluded that the amount of copper ions adsorbed (q e ) changes slightly with the increase of initial concentration of copper ions in solution (c 0 ), reaching its maximum value at an initial concentration of 11.091 mmol dm -3 with the value of q e = 0.265 mmol g -1 for the conditions under which the experiment was conducted. The copper ions adsorption efficiency reaches its maximum value for the lowest selected initial concentration of 2.876 mmol dm -3 with the value of 42.330 % and then decreases with the increase of initial concentration of copper ions in solution. The adsorption of copper on sieved humus can be described by the Langmuir adsorption model (R 2 = 0.995). Comparing the results with those obtained when untreated humus was used as adsorbent under the same experimental conditions, it can be concluded that the adsorption process of copper from copper(II) chloride dihydrate is nevertheless better performed on untreated humus (q e = 0.272 mmol g -1 and adsorption efficiency 46.990 %)
Organometallic compounds of the d-block transition metals : bachelor thesis
No full textKemija organometalnih spojeva smatra se u isto vrijeme starim i novim dijelom znanosti. Spojevi koji posjeduju najmanje jednu kovalentnu vezu između atoma ugljika i atoma metala nazivaju se organometalni spojevi. Metal u metalnim karbonilima istog koordinacijskog broja poput oksidacijskog stanja podliježe 18–elektronskom pravilu. Mingosovo pravilo nalazi primjenu pri brojanju ukupnog broja valentnih elektrona organometalnih spojeva d-bloka. Tim pravilima određivanjem broja elektrona dolazi se do spoznaje o strukturi određenog spoja. Organometalni spojevi prijelaznih elemenata su nestabilni zbog nepopunjenih d-orbitala i težnje organskih skupina da se eliminiraju kao olefini uz stvaranje metalnih hidrida (eliminacija vodika u β- položaju). Problem nestabilnosti rješava se odabirom adekvatnih liganada poput stabilizacijskih (CO) ili onih koji nemaju β-vodik (W(CH 2 SiMe 3 ) 6 ) ili onih čijem je β-vodiku teško pristupiti (Cr(CMe 3 ) 4 ) Ligandi koji čine komplekse s metalima prijelazne skupine elemenata su alkenski, alilni, dienski, polienski i kompleksi s cikličkim polienima. Najvažnije organometalne reakcije su supstitucija CO liganda, eliminacija β-vodika, eliminacija α-vodika, oksidativna adicija, te migracija vodika i alkila.The chemistry of organometallic compounds is considered to be both an old and a new part of science. Compounds that possess at least one covalent bond between a carbon atom and a metal atom are called organometallic compounds. Metal in metal carbonyls of the same coordination number as the oxidation state is subject to the 18 - electronic rule. The Mingos rule finds application in counting the total number of valence electrons of d-block organometallic compounds. By these rules, the number of electrons determines the structure of a particular compound. Organometallic compounds of transition elements are unstable due to unfilled d-orbitals and the tendency of organic groups to be eliminated as olefins with the formation of metal hydrides (elimination of hydrogen in the β-position). The problem of instability is solved by selecting adequate ligands such as stabilizing (CO) or those that do not have β-hydrogen (W(CH 2 SiMe 3 ) 6 ) or those whose β-hydrogen is difficult to access (Cr(CMe 3 ) 4 ). Ligands that form complexes with transition metals are alkene, allyl, diene, polyene and cyclic polyenes. The most important organometallic reactions are CO ligand substitution, β-hydrogen elimination, α-hydrogen elimination, oxidative addition, and hydrogen and alkyl migration
Effect of impeller type and baffle presence on ion exchange in batch reactor : diploma thesis
No full textU ovom radu istraživan je utjecaj tipa miješala i prisutnosti razbijala virova na ionsku izmjenu bakra na zeolitu NaX u kotlastom reaktoru. Eksperimenti su provedeni pojedinačno u kotlastom reaktoru s i bez razbijala virova korištenjem tri tipa miješala: turbinsko miješalo s ravnim lopaticama (SBT), turbinsko miješalo s lopaticama nagnutim pod kutom od 45° (PBT) i turbinsko miješalo s diskom i ravnim lopaticama (Rushtonova turbina, RT) s ciljem dobivanja uvida u utjecaj geometrije na hidrodinamiku sustava, a time i na proces ionske izmjene. Ispitivanje je provedeno s česticama zeolita veličine od 40 do 50 µm i otopine bakrova(II) nitrata početne koncentracije 7·10 -3 mol L -1 . Za svaku geometrijsku konfiguraciju reaktora i miješala određena je minimalna brzina vrtnje miješala (N JS ) pri kojoj se postiže stanje potpune suspenzije temeljem Zwieteringovog kriterija "1s", kao i utrošak snage miješala (P JS ) . Dobiveni rezultati parametara miješanja pokazali su veće vrijednosti prilikom korištenja razbijala virova. Izučavanjem kinetike ionske izmjene pokazalo se da tijekom prvog perioda procesa, količina izmijenjenog bakra naglo raste, nakon čega nagli rast prelazi u postepeni sve do postizanja ravnotežnog stanja. Provedena je i kinetička analiza eksperimentalnih podataka nelinearnom i linearnom regresijom korištenjem Ritchievog i Weber-Morrisovog modela kako bi se utvrdilo koji od procesa kontrolira kinetiku izmjene. Ritchiev model je pokazao najbolje slaganje s eksperimentalnim podacima i time je utvrđeno da ukupnu brzinu kemijske reakcije kontrolira proces ionske izmjene. Osim toga, proces ionske izmjene je brži u reaktoru s razbijalima virova za svaki tip miješala.In the present paper the influence of the impeller type, as well as the presence of baffles on the ion exchange of copper at zeolite NaX was investigated within a batch reactor. The experiments in the batch reactor were conducted separately with and without the presence of baffles using three types of impellers: straight blade turbine (SBT), pitch blade turbine (PBT) and Rushton turbine (RT), with the goal of obtaining an insight into the influence of geometry on hydrodynamics and on ion exchange kinetics, as well. The study was conducted with zeolite particles ranging from 40 to 50 µm and a copper (II) nitrate solution with initial concentration of 7·10 -3 mol L -1 . For each geometrical configuration of reactor and impeller used, just suspended impeller speed (N JS ) responsible for obtaining the state of complete suspension was determined based on the Zwietering's criterion "1s". Also, the value of power consumption (P JS ) was found. The obtained results show higher values when reactors with baffles were used. Study of ion exchange rate revealed that during the first part of process, the amount of copper exchanged increases fast whereupon that rapid growth gradually reaches the equilibrium state. Kinetic analysis of experimental results was carried out using non-linear and linear regression using Ritchie's and Weber-Morris models in order to determine which of the processes controls the exchange kinetics. Ritchie's model exhibited the best fitting with the experimental data, thus leading to a conclusion that overall reaction rate is controlled by the ion exchange process itself. Besides, the ion exchange process is faster in a reactor with baffles for all impeller types
Determination of equilibrium amount cobalt adsorbed on egg shells (T=308 K) : diploma thesis
No full textU ovom je diplomskom radu ispitana adsorpcija kobaltovih iona na ljuskama jaja u ovisnosti o različitim početnim koncentracijama otopina kobaltovih iona (4,284 mmol dm-3, 8,161 mmol dm-3, 11,223 mmol dm-3, 20,406 mmol dm-3, 30,610 mmol dm-3 te 40,202 mmol dm-3). Eksperiment je proveden pri stalnoj temperaturi od 308 K, brzini miješanja od 200 okr min-1, u trajanju od 96 h (kako bi se odredilo vrijeme uspostave ravnoteže), na ljuskama jaja promjera d < 0,250 µm. Koncentracije kobaltovih iona u ravnotežnim otopinama su određene spektrofotometrijski. Na temelju dobivenih rezultata može se zaključiti kako se količina adsorbiranih kobaltovih iona (qe) u početku ne mijenja s porastom ravnotežne koncentracije kobaltovih iona u otopini (ce), a zatim dolazi do naglog skoka i u konačnici do uspostave ravnoteže koja bi trebala predstavljati ravnotežnu količinu adsorbiranih kobaltovih iona na ljuskama jaja te iznosi qe = 0,082 mmol g-1 za uvjete pri kojima je eksperiment proveden (308 K, 200 okr min-1, 96 h). Učinkovitost adsorpcije kobaltovih iona dostiže svoju maksimalnu vrijednost za najnižu odabranu početnu koncentraciju od 4,284 mmol dm-3 te iznosi 4,764 % te nakon toga opada s porastom početne koncentracije kobaltovih iona u otopini. Iz svega navedenog može se zaključiti kako ljuske jaja nisu pogodan adsorbens za uklanjanje kobalta iz vodenih otopina.In this diploma thesis the adsorption of cobalt ions on egg shells was studied depending on the different initial concentrations of cobalt ions solutions (4.284 mmol dm-3, 8.161 mmol dm-3, 11.223 mmol dm-3, 20.406 mmol dm-3, 30.610 mmol dm-3 and 40.202 mmol dm-3). The experiment was carried out at a constant temperature of 308 K, stirring speed of 200 rpm for 96 h (in order to establish when the equilibrium occured), on egg shells with diameter d < 0.250 μm. Concentrations of cobalt ions in the equilibrium solutions were determined using spectrophotometer. Based on the results obtained it can be concluded that there is no change in the amount of cobalt ions adsorbed (qe) in the beginning with the increase of the equilibrium concentration of cobalt ions in solution (ce), and then there is a sudden jump in the amount of cobalt ions adsorbed which represents the equilibrium amount of cobalt ions adsorbed on egg shells with the value of qe = 0.082 mmol g-1 for the selected experiment conditions (308 K, 200 rpm, 96 h). The cobalt ion adsorption efficiency reaches its maximum value for the lowest initial starting concentration of 4.284 mmol dm-3 with the value of 4.64 % and then decreases with the increase of initial concentration of cobalt ion in solution. From all of the above it can be concluded that the egg shells are not suitable adsorbents for cobalt removal from aqueous solutions
Glucosinolate profile of white wall rocket (Diplotaxis erucoides). Conventional vs. microwave assisted isolation of volatiles : bachelor thesis
No full textGlukozinolati su sekundarni metaboliti koji su zastupljeni u 16 botaniĉkih porodica reda Capparales, a najznaĉajnija je porodica Brassicaceae u koju se ubrajaju dobro poznate biljke iz svakodnevne prehrane kao što su kupus, brokula, cvjetaĉa, prokulice, rotkvica, repa, gorušica i druge. Po kemijskoj strukturi to su β-tioglukozidni-N-hidroksisulfati s varijabilnim boĉnim lancem. Glukozinolati su kemijski i biološki neaktivni. Njihovom enzimskom, kemijskom ili termiĉkom razgradnjom nastaje niz biološki aktivnih produkata od kojih su najviše istaţivani izotiocijanati. U ovom radu primjenjene su razliĉite metode izolacije ukljuĉujući hidrodestilaciju, autolizu te mikrovalnu destilaciju i ekstrakciju kako bi se istraţila termiĉka, enzimska i mikrovalovima potpomognuta razgradnja glukozinolata. Posebno je zanimljiva mikrovalna ekstrakcija jer predstavlja pravi primjer uporaba zelene tehnologije. Cilj ovoga rada bio je izolirati i identificirati hlapljive sumporove spojeve iz dvoredca (Diplotaxis erucoides). Biljni materijal sakupljen je u Splitu u travnju 2019. Izolacija hlapljivih spojeva provedena je hidrodestilacijom po Clevengeru, autolizom te mikrovalnom destilacijom i ekstrakcijom bez dodatka otapala. Za identifikaciju izoliranih hlapljivih spojeva korištena je GC-MS tehnika. U listu i komuški dvoredca preko razgradnog produkta alil-izotiocijanata identificiran je sinigrin, dok je u korijenu, cvijetu i stabljici identificiran sinigrin preko alil-izotiocijanata te glukonasturcin preko 2-feniletil-izotiocijanata. HPLC-DAD tehnikom preko desulfoglukozinolata potvrĊeno je njihovo prisustvo te su navedeni spojevi i kvantizirani. Koncentracija sinigrina u listu bila je 12,0996 μmol/g, u stabljici 10,4135 μmol/g, u komuški 28,8295 μmol/g, u korijenu 2,6966 μmol/g i u cvijetu je 16,3358 μmol/g. Koncentracija glukonasturcina u stabljici bila je 0,7765 μmol/g, u korijenu 16,4398 μmol/g i u cvijetu je 0,2485 μmol/g.Glucosinolates are secondary metabolites present in 16 botanical families of the Capparales order, among which the most important is Brassicaceae family, which includes well-known plants of everyday nutrition such as cabbage, broccoli, cauliflower, broomsticks, radis, beets and others. Chemically these are β-thioglucoside-N-hydroxysulfates with a variable side chain. Glucosinolates are chemically and biologically inactive. Their enzymatic, chemical, and thermal degradation result in formation of series of biologically active products, among which the most studied ones are isothiocyanates. In our study, we used different methods including hydrodistillation, autolysis followed by extraction, and microwave assisted distillation and extraction in order to investigate thermal, enzymatic, and microwave-assisted decomposition of glucosinolates. Microwave extraction is particularly interesting because it represents a true example of green technology. The aim of this study was to isolate and identify volatile sulfur compounds from white wall rocket (Diplotaxis erucoides). Plant material was collected in Split in April 2019.The isolation of volatile compounds was performed by hydrodistillation in Clevenger type apparatus, autolysis and microwave distillation and extraction without solvent addition. GC-MS technique was used to identify the isolated volatiles. The leaf and siliquae volatile extractscontained allyl-isothiocyanate, the breakdown product ofsinigrin, while the root, flower and stem next to allyl-isothiocyanate also contained 2-phenylethyl- isothiocyanate, which originated from gluconasturtiin. Glucosinolates were also confirmed and quanified by HPLC-DAD technique. Leaf contained 12,0996 μmol/g of sinigrin, stem 10,4135 μmol/g, siliquae 28,8295 μmol/g, root 2,6966 μmol/g and flower 16,3358 μmol/g. Gluconasturtiin concentration in stem was 0,7765 μmol/g, in root 16,4398 μmol/g and in flower 0,2485 μmol/g
Green synthesis of colloidal silver using different natural reducing agents : bachelor thesis
No full textU ovom radu opisane su metode i postupci vezani uz zelenu sintezu koloidnog srebra različitim prirodnim reducensima. Zelena sinteza je tehnika koja povećava efikasnost proizvodnje komercijalno primjenjivih nanočestica s manjom ili nikakvom toksičnosti. Nanočestice srebra imaju primjenu u raznim područjima, no njihov utjecaj na okoliš iz godine u godinu je zabrinjavajući zbog upotrebe različitih sirovina i kemikalija pri sintezi, koje su skupe, toksične i opasne po okoliš. Stoga je zadnjih godina zelena sinteza sve više zastupljena jer je ekološki prihvatljivija i isplativija, odnosno manji su troškovi proizvodnje, manja potrošnja energije i smanjena ili potpuno uklonjena uporaba toksičnih kemikalija. Toksične kemikalije zamijenjene su s prirodnim tvarima iz okoliša koje su lako dostupne, kao što su biljni ekstrakti te mikroorganizmi. Živi organizmi poput bakterija, gljivica, biljaka i biomase imaju ogroman potencijal za proizvodnju metalnih nanočestica te su danas važan aspekt trenutnih istraživanja nanotehnologije.: In this thesis, there are described methods and procedures of green synthesis of colloidal silver using different natural reducing agents. Green synthesis is technique which increases production efficiency of commercially applicable nanoparticles with less or none toxicity. Silver nanoparticles are used in various fields, but their environmental impact in last years is concerning due to various materials and chemicals application in synthesis, which are expensive, toxic and environmentally dangerous. Therefore, last years green synthesis is even more represented because it is environmental-friendly and cost effective, the production costs are lower, lower energy consumption and reduced or completely eliminated use of toxic chemicals. Toxic chemicals are replaced by natural substances which are easily accessible, such as plant extracts and microorganisms. Living organisms like bacterias, fungi, plants and biomass have enormous potential for metal nanoparticles production and today they are important aspect of current nanotechnology researc
Volatile compounds of chestnut honey : bachelor thesis
No full textMed je slatki proizvod kojeg proizvode pčele složenom obradom prikupljenog cvjetnog nektara i sekreta biljnih sokova. U njemu su sadržani gotovo svi esencijalni sastojci ljudskog organizma. Primjenu nalazi u kulinarstvu, medicini i kozmetici. Aroma predstavlja jedno od najvažnijih svojstava meda koje doprinosi njegovoj kvaliteti, a nosioci arome u medu su hlapljivi spojevi. U ovom završnom radu određen je profil hlapljivih spojeva meda dobivenog od Zavoda za ribarstvo, pčelarstvo, lovstvo i specijalnu zoologiju Agronomskog fakultetu Sveučilišta u Zagrebu. Za izolaciju hlapljivih spojeva korištena je ekstrakcija potpomognuta ultrazvukom uz diklormetan kao otapalo. Izolirani spojevi iz diklormetanskog ekstrakta, analizirani su vezanim sustavom plinska kromatografija-masena spektrometrija. Glavni hlapljivi spojevi u svim ekstraktima meda kestena su 4-hidroksikinolin i p-aminoacetofenon, uz izuzetak jednog uzorka u kojem je je glavni hlapljivi spoj 2-feniloctena kiselina, a karakterizira ga i visoki udio 3-hidroksi- 4-fenilbutan-2-ona. Derivati benzena, 2-feniloctena kiselina i p-aminoacetofenon, glavni hlapljivi spojevi u USE ekstraktima kestenovog meda, karakteristični su za med kestena te se mogu smatrati markerima njegovog botaničkog porijekla. Prema rezultatima ovog rada i spoj s dušikom, alkaloid 4-hidroksikinolin bi također mogao biti karakteristični marker botaničkog porijekla kestenovog meda.Honey is a sweet product produced by bees by complex processing of collected flower nectar and secretions of plant juices. It contains almost all the essential ingredients needed by the human body. It is used in cooking, medicine and cosmetics. The aroma is one of the most important properties of honey that contributes to its quality, and the carriers of aroma in honey are volatile compounds. In this thesis, the profile of volatile compounds of honey obtained from the Department of Fisheries, Beekeeping, Hunting and Special Zoology of the Faculty of Agriculture, University of Zagreb is determined. At the same Institute, the monoflorality of the chestnut mode was confirmed by melisopalinological analysis. Ultrasonic assisted extraction with dichloromethane as solvent was used to isolate the volatile compounds. Isolated compounds from the dichloromethane extract were analyzed by coupled gas chromatography-mass spectrometry. The main constituents in all extracts of chestnut honey are 4-hydroxyquinoline and p-aminoacetophenone, with the exception of one extract in which the main volatile compound is 2-phenylacetic acid, and it is also characterized by a high content of 3-hydroxy-4-phenylbutan-2-one. Benzene derivatives, 2-phenylacetic acid and p- aminoacetophenone, are characteristic of the chestnut honey and can be considered as markers of its botanical origin. According to the obtained results, nitrogen containing compound alkaloid 4-hydroxyquinoline could also be considered as a potential marker of the botanical origin of chestnut honey
Hydration of calcium sulfoaluminate cement in the system of paste and suspension : master thesis
No full textKalcij sulfoaluminatni cement (CSA), je alternativa portland cementu (OPC). Tehnologija proizvodnje CSA karakterizirana je manjom emisijom ugljikovog dioksida, nižim temperaturama proizvodnje te mogućnošću korištenja otpadnog materijala kao sirovine. CSA u odnosu na OPC, razvija veće rane čvrstoće, brže očvršćava i posjeduje bolja antikorozivna svojstva. U ovom radu istraživana su hidratacijska svojstva tržišno dostupnog cementa Ali Pre Green (Italcementi, Heidelberg Cement Group). Hidratacija cementa je provedena u sustavu cementnih pasta s vodocementnim omjerom (v/c = 0,31 i 0,5) i suspenzija (v/c = 4). Hidratacijom nastale faze određene su termogravimetrijom (TG / DTG-DTA) i difrakcijom X-zraka na prahu (XRD). Istraživanje sustava cementnih suspenzija i pasta ukazuje na vrlo visoku hidratacijsku aktivnost do 48 sati u sustavima pasta i do 24 sata u vodenim suspenzijama. Ukupna oslobođena toplina hidratacije usporediva je s vrijednostima za OPC, dok je glavni produkt hidratacije u vodenim suspenzijama etringit.Calcium sulfoaluminate cement (CSA) is a sustainable alternative to Ordinary Portland Cement (OPC). The producing technology of CSA is characterised by lower carbon dioxide emission, lower temperature for producing clinker and the possibility to reuse waste materials as raw materials in the production process. CSA has an advantage compared to the OPC, such as higher early strength, faster hardening, and better anti-corrosion properties. In this paper, research is focused on the hydration on the market commercially available Ali Pre Green as CSA cement (Italcementi, Heidelberg Cement Group). Hydration of cement was carried out in a system of cement pastes with a ratio of water/cement = 0.31 (w/c) and suspension (w/c = 4). The content of the hydration product was determined by thermal methods (TG / DTG-DTA), X-ray diffraction (XRD). Research on cement paste and suspension systems indicates very high hydration activity of up to 48 hours in paste systems and up to 24 hours in aqueous suspensions. The total heat of hydration released is comparable to the values for OPC until the main product of hydration in the system of water suspension is Ettringite