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Study of the solvent effect on the application of selected species from the Berberidaceae family as acid-base indicator
No full textpH vrijednost je vrlo bitna mjera koja nam govori o uvjetima u otopini, a određivanje pH vrijednosti ne veže se samo uz laboratorij već se koristi i u druge svrhe. Za određivanje pH vrijednosti koriste se pH indikatori koji su još poznati pod nazivom kiselo-bazni indikatori. Danas su u upotrebi mnogi sintetski indikatori, kao što su metiloranž, fenolftalein i lakmus papir. Osim njih, sve se više ispituju prirodni indikatori. Biljke porodice Berberidaceae, obična žutika (Berberis vulgaris L.) i vazdazelena mahonija (Mahonia aquifolium (Pursh.) Nutt.), sadrže u svojim plodovima antocijanine osjetljive na promjenu pH vrijednosti, odnosno pod utjecajem promjene pH promjeni se struktura ovih spojeva, zbog čega apsorbiraju svijetlost na različitim valnim duljinama što se manifestira promjenom boje. U ovom radu, ispitane su svježe i suhe bobice obične žutike i vazdazelene mahonije u kombinaciji s odabranim otapalima (voda, vruća voda, metanol, etanol i aceton) kao kiselo-bazni indikatori. Rezultati ispitivanja ukazuju na potencijal plodova ovih biljaka kao kiselo-baznih indikatora. Prednost ovako priređenih indikatora je velika dostupnost ovog biljnog materijala, jednostavno skladištenje i mogućnost korištenja cijele godine. Svježi plodovi pokazuju vizualno dojmljivu promjenu boje u svim otapalima, dok u slučaju suhih plodova samo obična žutika u etanolu i acetonu pokazuje intenzivniju promjenu boje.The pH value is a very important measure that tells us about the conditions in the solution and determination of the pH value is not only related to the laboratory, but is also used for other purposes. pH indicators, also known as acid-base indicators, are used to determine the pH value. Nowadays, there are many synthetic indicators in use, such as methyl orange, phenolphthalein and litmus paper. Apart from them, the number of studies dealing with natural pH indicators are increasing. Plants of the Berberidaceae family, common barberry (Berberis vulgaris L.) and holly-leaved barberry (Mahonia aquifolium (Pursh.) Nutt.), contain anthocyanins in their fruits that are sensitive to changes in pH value. The change of the pH leads to a change of their structure, hence they absorb light at different wavelengths what manifests as a change in colour. In this thesis, fresh and dry fruit (berries) of common barberry and holly-leaved barberry in combination with selected solvents (water, hot water, methanol, ethanol and acetone) was studied as acid-base indicator. The results indicate the potential of these plants as acid-base indicators. Advantage these indicators have is great availability of this plant material, simple storage and usability all year round. Fresh fruits show visually impressive colour change in all solvents. In the case of dried fruits, only common barberry shows a more intense color change in ethanol and acetone
Investigation of photocatalytic activity of (un)doped ceria
No full textCerij je jedan od elemenata rijetkih zemalja. Njegova jedinstvena svojstva proizlaze iz nepopunjene 4 f orbitale i kontrakcije lantanoida te posjeduje dva oksidacijska stanja: +3 i +4. Prijelazom između Ce4+ i Ce3+ oksidacijskog stanja ne dolazi do narušavanja stabilnosti floritne strukture pa u CeO2 može doći do promjene udjela kisika u ovisnosti o promjeni temperature, tlaka, električnog polja i prisutnosti dopanata. Transport kisika u kristalnoj rešetki CeO2 rezultat je stvaranja točkastih defekata. U ovom završnom radu sintetizirano je 4 uzorka koristeći ultrazvučno potpomognutu sintezu, a njihova svojstva su ispitana koristeći IR spektroskopiju, termogravimetrijsku analizu te rentgensku difrakciju na prahu. Fotokatalitička aktivnost sintetiziranih uzoraka ispitana je na razgradnju dva organska bojila koristeći UV/VIS uređaj. Cilj ovog rada bio je utvrditi na koji način dopiranje CeO2 utječe na njegovu fotokatalitičku aktivnost.Cerium is one of the rare earth elements. Its unique properties originate from the unfilled 4 f orbital and the lanthanoid contraction, and it has two oxidation states: +3 and +4. The transition between the Ce4+ and Ce3+ oxidation states does not affect the stability of the fluorite structure, so in CeO2 the oxygen content can change depending on the change in temperature, pressure, electric field and the presence of dopants. Oxygen transport in the CeO2 crystal lattice is the result of the formation of defects. In this work, 4 samples were synthesized using ultrasound - assisted synthesis, and their properties were examined using IR spectroscopy, thermogravimetric analysis, and X-ray powder diffraction. The photocatalytic activity of the synthesized samples was tested for the degradation of two organic dyes using a UV/VIS device. The aim of this work was to determine how does doping of CeO2 affects its photocatalytic activity
Configurational entropy impact on the physical properties of selected complex perovskites
No full textModificiranom sol-gel sintezom pripravljeni su dvostruki perovskiti (Sr, Ba)2B(W, Te)O6. Cilj ovog rada je sintetizirati fazno čiste spojeve uvođenjem novih kationskih vrsta na B položaj perovskita. Cilj uvođenja novih kationskih vrsta je postizanje visoke entropije u svrhu snižavanja slobodne Gibbsove energija kako bi novi visokoentropijski spoj bio stabilan. Priređeni spojevi su nakon sinteze detaljno strukturno okarakterizirani rentgenskom difrakcijom u prahu (PXRD), Ramanovom spektroskopijom, termogravimetrijskom analizom i BET analizom, a fotokatalitička aktivnost im je određena UV/Vis spektroskopijom.Double perovskites (Sr, Ba)2B(W, Te)O6 were synthesized by modified sol-gel synthesis. The primary goal of this work was to synthesize phase-pure compounds by doping them with new cation species in the B site of the mentioned perovskites. The primary objective of introducing new cation species into the system was to increase the entropy of the system, and therefore, to lower the Gibbs energy in order to make the system more stable. After the synthesis, prepared compounds were structurally characterized by Powder X-ray diffraction (PXRD), Raman spectroscopy, Thermogravimetric analysis, and BET analysis. Lastly, the photocatalytic activity has been measured by UV/Vis spectroscopy
Determination of refractive index and oil color
No full textTransformator je uređaj koji pretvara izmjeničnu struju zadanoga napona u izmjeničnu struju višeg ili nižeg napona i kao takav ključan je u prijenosu električne energije od proizvođača do potrošača, jer smanjuje gubitak energije. Svaki transformator u sebi sadrži ulje koje služi kao izolacijska i rashladna tekućina, a uz to ulje daje informacije o kvaliteti transformatora. S vremenom transformatorsko ulje oksidira i postane onečišćeno, a sve to se odražava na kemijska i fizikalna svojstva ulja što u konačnici stvara nekvalitetno ulje za rad transformatora. Postoji tri vrste ulja koja se koriste u transformatorima, a to su mineralna, silikonska i esterska. U ovom radu koristila su se mineralna izolacijska ulja, osam uzoraka s područja Slavonije. Svrha ovog rada je proučiti metode kojima se određuje kvaliteta transformatorkog ulja, usporediti njihove rezultate i na temelju svih rezultata donijeti zaključak o ispravnosti ulja. Naglasak je na metodama određivanja refrakcijskog indeksa i boje ulja.A transformer is a device that converts alternating current of a given voltage into alternating current of higher or lower voltage and as such is crucial in the transmission of electricity from the producer to the consumer, because it reduces energy loss. Each transformer contains an oil that serves as an insulating and cooling liquid, and in addition the oil provides information on the quality of the transformer. Over time, transformer oil oxidizes and becomes contaminated, all of which is reflected in the chemical and physical properties of the oil which ultimately creates poor quality oil for the operation of the transformer. There are three types of oils used in transformers: mineral oil, silicone oil and ester oil. In this work are used mineral insulating oils, eight samples from the area of Slavonia. The purpose of this final work is to study the methods used to determine the quality of transformer oil, to compare their results and on the basis of all the results to draw a conclusion about the correctness of the oil. The emphasis is on methods for determining the refractive index and oil color
Influence of anions on the molecular and crystal structure of silver complexes with macrocyclic Schiff bases
No full textPredmet istraživanja ovog diplomskog rada je utjecaj aniona na molekulsku i kristalnu građu srebrovih kompleksa sa makrocikličkim Schiffovim bazama. Pripremljena je makrociklička Schiffova baza koja je služila kao ligand, a kao metalne soli prijelaznih elemenata koristili su se srebrov perklorat (AgClO4), srebrov heksafluorofosfat (AgPF6). srebrov heksafluoroantimonat (AgSbF6) i srebrov tetrafluoroborat (AgBF4). Priprava srebrovih kompleksa izvedena je uz odgovarajući ligand i metalni kation u U-cijevi uz diklormetan i metanol kao otapalo. Od izvedenih sinteza uspješno su izolirane i identificirane 4 nove kristalne strukture. Dobiveni spojevi su karakterizirani IR spektroskopijom (FT-IR), a molekulske i kristalne strukture određene su rendgenskom difrakcijom.The subject of this thesis is the influence of anions on the molecular and crystal structure of silver complexes with macrocyclic Schiff bases. A prepared macrocyclic Schiff base served as a ligand, and silver perchlorate (AgClO4), silver hexafluorophosphate (AgPF6), silver hexafluoroantimonate (AgSbF6) and silver tetrafluoroborate (AgBF4) were used as metal salts. Preparation of silver complexes was performed with the appropriate ligand and metal salt in a U-shaped tube with dichloromethane and methanol as solvent. From the performed syntheses, 4 new crystal structures were successfully isolated and identified. The obtained compounds were characterized by IR spectroscopy (FT-IR), and molecular and crystal structures were determined by X-ray diffraction
The application of dry aronia fruit, Aronia melanocarpa (Michx.) Elliott, as acid-base indicator
No full textU učionici kemije, prirodni indikatori odlična su zamjena konvencionalnim indikatorima. Osim što su cjenovno dostupniji, mogu biti vizualno dojmljivi i omogućavaju povezivanje gradiva sa svakodnevnim životom, čime olakšavaju proces učenja. Cilj ovog rada bio je ispitati potencijal primjene suhog ploda aronije, Aronia melanocarpa (Michx.) Elliott, kao prirodnog kiselo-baznog indikatora. U tu svrhu je pripremljen niz indikatora od suhe aronije i odabranih otapala (voda, metanol, etanol, aceton). Funkcionalnost indikatora ispitivana je u periodu od četiri mjeseca, nakon čega je ispitana mogućnost recikliranja ovih indikatora. Indikatori su bili funkcionalni sve vrijeme ispitivanja, a biljni materijal korišten u pripremi indikatora pokazao je mogućnost recikliranja. Stoga se može reći da su ovakvi indikatori "zeleni" indikatori, budući da pri njihovoj pripremi nema otpadnog materijala i budući da se mogu učinkovito reciklirati. Među ispitanim otapalima, kao vizualno najdojmljiviji pokazao se metanol, budući da je indikator pripremljen s metanolom dao lijepe i intenzivne boje.In the chemistry classroom, natural indicators are an excellent substitute for conventional indicators. Aside from price availability, they can be visually impressive and allow efficient correlation of lectures with everyday life and easier learning process. The aim of this thesis was to evaluate the potential of dry aronia fruit, Aronia melanocarpa (Michx.) Elliott, as natural acid-base indicator. For this purpose, a series of indicators containing dry aronia and selected solvents (water, methanol, ethanol, acetone) was prepared. Indicator activity was studied for four months, after which recyclability of indicators was evaluated. Indicators were functional during study period, and used plant material showed potential for recycling. Hence, we can say that in this way prepared indicators are "green" indicators, because there was no waste from their preparation and they can be successfully recycled. Among studied solvents, visually most impressive was methanol, since indicator prepared with methanol showed beautiful and intense colours
Extraction of metal cations with porous oxo-aza macrocyclic compounds
No full textMakrociklički spojevi definiraju se kao makromolekule cikličke strukture ili ciklički dio makromolekule. Ovi spojevi mogu se promatrati kao polidentatni ligandi čiji strukturni "okvir" gradi minimalno 9 atoma od kojih je najmanje 3 potencijalno donorskih atoma. Za raširenost primjene makrocikličkih Schiffovih baza u ulozi liganda, zaslužna je jednostavna metoda sinteze. U ovome radu opisana je sinteza i karakterizacija Schiffove baze ( pDo5 = 1,6,20,25 - tetraaza - 2,5:8,9:17,18:21,24:27,28:36,37 - heksabenzo - 10,16,29,35-tetraoksa-ciklooktatriakonta-1,6,20,25 - tetraen ) i reducirana Schiffova baza pDo5R (1,6,20,25 - tetraaza - 2,5:8,9:17,18:21,24:27,28:36,37 - heksabenzo - 10,16,29,35-tetraoksa-ciklooktatriakonta). Dobiveni produkti okarakterizirani su FT-IR i NMR spektroskopijom te je ispitana ekstrakcija metalnih kationa iz vodenih otopina. Provedena je ekstrakcija metalnih kationa, a korišteno je 12 metalnih soli: Cu2+, Ag+, Au3+, Fe3+, Co2+, Hg2+, Cr3+, Ni2+, Cd2+, Zn2+, Mn2+, (HAuCl4 x 3 H2O). Rezultati su pokazali selektivnu ekstrakciju Cu2+ korištenjem pDo5 spoja te izvrsnu ekstrakciju Co2+, Ag+, Au3+ i Fe3+ kationa pomoću spoja pDo5R.Macrocyclic compounds are defined as macromolecules with cyclic structure or the cyclic part of the macromolecule. These compounds can also be considered as polydentate ligands whose structural frame is built from minimally 9 atoms, of which at least 3 are potentially donor atoms. The widespread use of macrocyclic Schiff bases in a role of a ligand is due to a simple synthesis method. This paper describes the synthesis and characterization of Schiff's base (pDo5 = 1,6,20,25 - tetraaza - 2,5:8,9:17,18:21,24:27,28:36,37 - heksabenzo - 10,16,29,35-tetraoksa-ciklooktatriakonta-1,6,20,25 - tetraen) and reduced Schiff base pDo5R (1,6,20,25 - tetraaza - 2,5:8,9:17,18:21,24:27,28:36,37 - heksabenzo - 10,16,29,35-tetraoksa-ciklooktatriakonta). The obtained products were characterized by FT-IR and NMR spectroscopy and the extraction of metal cations from aqueous solutions was investigated. The extraction of metal cations was carried out, and 12 metal salts were used: Cu2+, Ag+, Au3+, Fe3+, Co2+, Hg2+, Cr3+, Ni2+, Cd2+, Zn2+, Mn2+, (HAuCl4 x 3 H2O). The results showed selective Cu2+ extraction using the pDo5 compound and excellent extraction of Co2+, Ag+, Au3+ and Fe3+ cation using the pDo5R compound
Mechanochemical synthesis of transition metal complexes in zeolites
No full textZeoliti su aluminosilikati, klasa poroznih spojeva sa šupljinama i kanalima različitih veličina i oblika. Često se upotrebljavaju za pripremu inkluzijskih spojeva koji se mogu iskoristiti za razne primjene, kao što su kataliza, apsorpcija plinova te ionska izmjena. Kompleksni se spojevi mogu prirediti unutar šupljina zeolita otopinskom sintezom kako bi se utjecalo na njihova svojstva. Mehanokemija je grana kemije koja koristi mehaničku energiju za provedbu reakcija. Budući da se reakcije provode u krutom stanju, za njih nije potrebno koristiti velike količine otapala. To čini mehanokemiju jeftinijom, bržom i ekološki osvještenijom alternativom za klasičnu sintezu u otopini. Cilj ovog rada je mehanokemijski sintetizirati kompleksne spojeve nikla(II) i bakra(II) unutar zeolita Y bez korištenja otapala. Dobiveni produkti analizirani su IR spektroskopijom i difrakcijom rentgenskog zračenja u polikristalnom uzorku.Zeolites are aluminosilicates, a class of porous compounds comprised of canals and cavities of different shapes and sizes. This makes them great candidates for preparation of inclusion compounds which have many uses, like reaction catalysis, gas absorption, ion-exchange etc. Complex coordination compounds can be synthesised inside the structure of a zeolite using solution synthesis methods to modify the properties of the material. Mechanochemistry is a branch of chemistry which uses mechanical energy to bring about a chemical reaction. Because those reactions are conducted in solid-state, no solvent is used which makes mechanochemistry a cheap, quick and eco-friendly alternative to classis solution synthesis. The goal of this research is to prepare transition metal complexes inside of zeolite Y's crystal structure without the use of any solvents. Synthesis of nickel and copper cyanides was chosen for this purpose. The results were analysed by IR spectroscopy and powder X-ray diffraction
Study of the application of dry stone fruit as acid-base indicator
No full textPojam koštuničavo voće obuhvaća velik broj voća koje je rasprostranjeno po cijelom svijetu. Odnosi se na voće čiji plod ima tvrdu košticu u sredini. Najpoznatiji predstavnici su šljiva, breskva, trešnja, višnja, itd. Brojne vrste koštuničavog voća sadrže pigmente koji u ovisnosti o pH mijenjaju boju otopine. Zbog toga je takav biljni materijal pogodan kao alternativni kiselo-bazni indikator. Cilj istraživanja bio je ispitati može li suho koštuničavo voće poslužiti kao kiselo-bazni indikator. Korištene su suhe višnje, trešnje, šljive, breskve, marelice, nektarine, ringlov, japanske trešnje i drenjina. Kao otapala za pripremu indikatora korišteni su aceton, etanol i metanol. Preliminarno ispitivanje izvedeno je na višnji kako bi se odredio optimalni omjer biljnog materijala i otapala. Sve voće bilo je iznimne čistoće, bez primjesa i onečišćenja koji bi mogli utjecati na rezultate ispitivanja. Istraživanje je pokazalo kako se suho koštuničavo voće, u najvećoj mjeri šljiva, višnja i trešnja, može uspješno koristiti kao prirodni kiselo-bazni indikator.The term stone fruit refers to a number of fruit that are widespread throughout the world. It refers to fruit which has a stone in the middle of the fruit. The most famous representatives are plums, peaches, sour cherries, sweet cherries, etc. Many species of this type of fruit contain pigments that change colour depending on the pH of the medium. Because of this fact, such plant material is appropriate as an alternative acid-base indicator. The aim of this study was to examine whether dry stone fruit could serve as an acid-base indicator. Dried sour cherries, sweet cherries, plums, peaches, apricots, nectarines, cherry plums, Japanese cherries and Cornelian cherries have been used. Acetone, ethanol and methanol were used as solvents for indicator preparation. The preliminary research was performed on cherries in order to determine optimal ratio of plant material and solvent. All used fruit were pure, with no additives or impurities that could impact results in any way. Research has shown that dry stone fruit, mainly plums and cherries, can be successfully used as a natural acid-base indicator
New quaternary ammonium salt as an antimicrobial agent and an active ingredient of hte potentiometric sensor for tenzides
No full textNova kvarterna amonijeva sol (QAC) - kationski tenzid 2-metil-1,3-dioktadecil-benzo[d]imidazol (MDBI) korišten je kao protu-ion u ionoforu za izradu i testiranje potenciometrijskog senzora za tenzide i kao antimikrobni agens. Kationski tenzidi često imaju antimikrobna svojstva i primjenjuju se kao antiseptici i dezinficijensi. Najnoviji primjer su dezinficijensi za suzbijanje širenja SARS-CoV-2 virusa na bazi QAC-ova ili alkohola. Ionofor za senzor za tenzide na bazi PVC tekuće mambrane bio je MDBI s terefenilborat (TPB) protu-ionom. Senzor je uspješno izrađen i okarakteriziran te testiran na modelnim sustavima i realnim sustavima otpadnih voda i komercijalnih proizvoda. Antimikrobno djelovanje MDBI uspoređeno je s komercijalnim sredstvom za čišćenje kupaonica koji sadrži kationski tenzid (Cilit BANG®) na 5 sojeva mikroorganizama gdje je kao hranjiva podloga za bakterije korišten Mueller - Hinton agar, a za kvasce i plijesni Sabouraud agar. Ispitivani mikroorganizmi su: Pseudomonas aeruginosa, Staphylococcus aureus, Aspergillus niger, Escherichia coli te Candida albicans. Izmjerene su njihove zone inhibicije. Usporedbom zona inhibicije za MDBI i Cilit BANG®, MDBI je pokazao superiornost u inhibiciji Pseudomonas aeruginosa koji je rezistentan na uobičajne antimikrobne agense.A new quaternary ammonium salt (QAC) - cationic surfactant 2-methyl-1,3-dioctadecyl-benzo[d]imidazole (MDBI) was used as a counterion in an ionophore for making and testing a potentiometric sensor for surfactants and as an antimicrobial agent. Cationic surfactants often have antimicrobial properties so they are used as antiseptics and disinfectants. The most recent example are disinfectants based on QACs or alcohol which are used for controlling the spread of the SARS-CoV-2 virus. The ionophore for the surfactant sensor based on PVC liquid membrane was MDBI with terephenylborate (TPB) as the counterion. The sensor was successfully manufactured, characterized, and tested on model systems, real wastewater systems, and commercial products. The antimicrobial activity of MDBI was tested and compared with a commercial bathroom cleaner containing a cationic surfactant (Cilit BANG®) on 5 strains of microorganisms, where Mueller-Hinton agar was used as a growth medium for bacteria, and Sabouraud agar was used for yeasts and molds. The observed microorganisms were: Pseudomonas aeruginosa, Staphylococcus aureus, Aspergillus niger, Escherichia coli, and Candida albicans. Their zones of inhibition were measured. By comparing the zones of inhibition for MDBI and Cilit BANG®, MDBI showed superiority in the inhibition of Pseudomonas aeruginosa, which is resistant to common antimicrobial agents