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Adsorption of cobalt ions on pistachio shells : diploma thesis
No full textU ovom je diplomskom radu ispitana adsorpcija kobaltovih iona na ljuskama pistacija u ovisnosti o različitim početnim koncentracijama otopina kobaltovih iona (3,543; 7,028; 10,061; 17,138 te 24,452 mmol dm -3 ) pri stalnoj temperaturi od 303 K, brzini miješanja od 200 okr min -1 , u trajanju od 96 h. Uočava se, na temelju dobivenih rezultata, eksponencijalan porast količine adsorbiranih kobaltovih iona na ljuskama pistacija ( qe ) s porastom početne koncentracije kobaltovih iona u otopini ( c0 ). Pri najvišoj odabranoj koncentraciji postignute su i maksimalna vrijednost količine adsorbiranih kobaltovih iona koja iznosi qe = 0,529 mmol g -1 i najviša učinkovitost adsorpcije kobaltovih iona koja iznosi 10,826%. Uzimajući u obzir izračunate vrijednosti za koeficijent korelacije R 2 može se zaključiti kako Langmuirov adsorpcijski model bolje opisuje adsorpciju kobaltovih iona na ljuskama pistacija od Freundlichovog adsorpcijskog modela.In this diploma thesis, the adsorption of cobalt ions on pistachio shells was studied depending on different initial concentrations of cobalt ions solutions (3.543, 7.028, 10.061, 17.138 and 24.452 mmol dm -3 ) at a constant temperature of 303 K, a stirring speed of 200 rpm -1 for 96 h. Based on the results obtained, an exponential increase in the amount of adsorbed cobalt ions on pistachio shells ( qe ) with an increase in the initial concentration of cobalt ions in solution ( c0 ) was observed. At the highest selected concentration, the maximum value of the amount of adsorbed cobalt ions, with the value of qe = 0.529 mmol g -1 , and the highest adsorption efficiency of cobalt ions, with the value of 10.826%, were achieved. Taking the calculated values for the correlation coefficient R 2 into account, it can be concluded that the Langmuir adsorption model better describes the adsorption of cobalt ions on pistachio shells unlike the Freundlich adsorption model
Adsorption and adsorption isotherm models : bachelor thesis
No full textAdsorpcija je široko primjenjiv postupak odvajanja, posebno u sanaciji okoliša, zbog svojih niskih troškova i visoke učinkovitosti. Mehanizam adsorpcije uglavnom uključuje kemijsku adsorpciju koja nastaje stvaranjem kemijskih veza, fizikalnu adsorpciju povezanu s van der Waalsovom silom i ionsku izmjenu. Jednadžbe adsorpcijskih izotermi koje se koriste za opisivanje eksperimentalnih podataka i termodinamičke pretpostavke modela često daju uvid u mehanizam adsorpcije, površinska svojstva i afinitet adsorbensa, što je važno za projektiranje adsorpcijskog sustava. Pregledom literature vidljivo je da su različiti adsorpcijski izotermi modeli predstavljeni na temelju dva, tri, četiri i pet parametara.Adsorption is widely applied separation process, especially in environmental remediation, due to its low cost and high efficiency. The adsorption mechanism mainly includes chemical adsorption corrsponding to the formation of chemical bonds, physical adsorption related to the van der Waals force, and the ion exchange. The adsorption isotherm equations used to describe the experimental data and the thermodynamic assumptions of the models often provide some insight into the adsorption mechanism, the surface properties and affinity of the adsorbent, which is important for the design of adsorption system. It is evident from the literature survey that various adsorption isotherm models have been presented on the basis of two, three, four and five parameters respectively
Life cycle assessment of municipal waste menagement systems: a case study of the city of Dubrovnik : diploma thesis
No full textU ovom diplomskom radu analizirano je integralno gospodarenje komunalnim otpadom primjenom aplikacijske programske podrške za procjenu životnog ciklusa Integrated Waste Management Model. Integralno gospodarenje otpadom podrazumijeva cjelovito sagledavanje životnog vijeka otpada i njegovo kruženje (kretanje) u okolišu zbog optimalnog upravljanja otpadom uz visok stupanj zaštite zdravlja i očuvanje okoliša. Procjena životnog ciklusa sustava gospodarenja komunalnim otpadom promatrana je na primjeru Grada Dubrovnika. Na temelju podataka o otpadu za 2019. godinu za Grad Dubrovnik razmatrana su četiri scenarija gospodarenja komunalnim otpadom u skladu s ciljevima EU Direktive o otpadu. Analizom i usporedbom utjecaja na okoliš svih scenarija gospodarenja otpadom ukazalo se na ključne razlike u postupanju s otpadom. Predložene su smjernice razvoja budućeg učinkovitijeg sustava gospodarenja komunalnim otpadom koji bi imao najmanje štetnih posljedica na okoliš i kvalitetu života.The life cycle assessment software Integrated Waste Management Model is used to study integrated municipal waste management in this diploma thesis. Integral waste management entails a holistic perspective of wastes’ life cycle and movement (circulation) in the environment in order to achieve optimal waste management with a high level of health and environmental protection. On the example of the City of Dubrovnik, the assessment of the life cycle of the municipal waste management system was observed. Based on 2019 waste data for the City of Dubrovnik, four municipal waste management scenarios were explored in compliance with the EU Waste Directive's objectives. The environmental impact of all waste management scenarios was analyzed and compared, revealing significant disparities in waste management. Guidelines for the construction of a future efficient municipal waste management system with the fewest negative environmental and quality-of-life effects have been offered
Mechanical recycling of single-use face masks : master thesis
No full textU ovom radu ispitan je utjecaj mehaničkog recikliranja na svojstva jednokratnih maski za lice. Jednokratne maske za lice su mehanički reciklirane koristeći jednopužni ekstruder. FTIR, TG i DSC korišteni su kako bi se odredila struktura i toplinska svojstva svakog sloja jednokratne maske za lice, jednokratne maske za lice prije i nakon recikliranja. FTIR analiza je potvrdila da je polipropilen glavni polimer sadržan u svakom sloju jednokratne maske za lice. Utjecaj recikliranja jednokratnih maski za lice na toplinska svojstva istražen je diferencijalnom pretražnom kalorimetrijom i termogravimetrijskom analizom. Neizotermnom termogravimetrijom utvrđeno je da recikliranje jednokratnih maski za lice nema utjecaj na toplinsku stabilnost. Primjenom diferencijalne pretražne kalorimetrije utvrđeno je da recikliranje utječe na kristalnost jednokratnih maski za lice.In this paper, influence of mechanical recycling on the properties of a single-use face masks was examined. Single-use face masks were mechanically recycled by using a laboratory single-screw extruder. FTIR, TG and DSC were used to determine the structure and thermal properties of each layer of the single-use face mask, single-use face mask before and after recycling. FTIR analysis confirmed that polypropylene is the main polymer that composes each layer of the single-use face mask. The influence of recycling of a single-use face mask on its thermal properties was investigated by differential scanning calorimetry and non-isothermal thermogravimetric analysis. It was found by non-isothermal thermogravimetry that recycling does not affect thermal stability of single-use face masks. By using differential scanning calorimetry, it was determined that recycling affects the crystallinity of single-use face masks
Biochar preparation from pistachio shells : master thesis
No full textPripremljeni su uzorci biougljena karbonizacijom ljuski pistacija pri tri različite temperature (350°C, 450°C i 550°C). Na pripremljenim uzorcima biougljena provedena je djelomična analiza s ciljem određivanja udjela vlage, pepela te isparljive i stalne tvari te su ispitana njihova adsorpcijska svojstva. Porast temperature je doveo do smanjenja prinosa na uzorcima biougljena te je sukladno tome najmanji prinos na uzorku biougljena pripremljenom pri temperaturi karbonizacije od 550°C. Također, udio isparljivih tvari se smanjuje s porastom temperature. Sadržaj stalne tvari raste s porastom temperature karbonizacije, kao i udio pepela i vlage. Najzastupljenije čestice su one koje pripadaju frakciji 90-100 µm kod svih pripremljenih uzoraka biougljena. U uzorcima biougljena pripremljenim pri dvije više temperature (450°C i 550°C) uočavaju se sitne svjetlije čestice koje bi mogle pripadati ostatcima sagorene organske tvari. Količina adsorbiranih bakrovih iona, kao i učinak adsorpcije rastu porastom temperature pri kojoj je pripremljen biougljen.Biochar samples were prepared by carbonizing pistachio shells at three different temperatures (350°C, 450°C and 550°C). Proximate analysis was performed on the prepared biochar samples in order to determine moisture content, ash, and mobile and resident matter, and their adsorption properties were tested as well. The increase in temperature led to a decrease in the yield of the biochar samples and, accordingly, the lowest yield was on the biochar sample prepared at a carbonization temperature of 550°C. Also, the content of volatile substances decreases with the temperature increase. The content of resident matter increases with the increase in carbonization temperature, as well as the content of ash and moisture. The most abundant particles fall into the 90-100 µm fraction in all prepared biochar samples. In the biochar samples prepared at two higher temperatures (450°C and 550°C), tiny light-pale particles can be observed, which could be the remains of burned organic matter. The amount of adsorbed copper ions, as well as the adsorption efficiency, increase with the temperature at which the biochar was prepared
Volatile compounds of flavoured cheeses : diploma thesis
No full textU ovom diplomskom radu analiziran je sastav i sadržaj hlapljivih spojeva punomasnog tvrdog sira od kravljeg mlijeka i istih sireva kojima su dodani ekstrakti aromatičnog bilja (lavanda, smilje i vrisak) te aromatično bilje u suhoj tvari (lavanda). Izolacija hlapljivih spojeva izvršena je mikroekstrakcijom vršnih para na krutoj fazi korištenjem vlakna sastava divinilbenzen/karboksen/polidimetilsiloksan (DVB/CAR/PDMS) pri temperaturi od 60 ℃. Svi uzorci analizirani su vezanim sustavom plinska kromatografija-spektrometrija masa na nepolarnoj koloni, a dobiveni rezultati su raspravljeni i uspoređeni. U većini uzoraka najzastupljenije su karboksilne kiseline, posebno masne kiseline heksanska, butanska, oktanska te octena kiselina. Izuzetak je sir bez dodataka gdje je najzastupljeniji spoj metilketon nonan-2-on. U ispitanim sirevima s dodatkom ekstrakta aromatičnog bilja te suhog biljnog materijala (lavanda) identificirani su i terpeni, dok u siru bez dodataka nije identificiran ni jedan terpen. Za sireve s dodatkom ekstrakta vrijedi: što je udio pojedinog ekstrakta aromatičnog bilja u siru veći, veći je i udio terpena.In this diploma thesis, the composition and content of volatile compounds in full-fat hard cheese made from cow's milk were analysed, including those cheeses to which extracts of aromatic herbs (lavender, immortelle and savory) and aromatic herbs in dry matter (lavender) were added. Isolation of volatile compounds was performed by headspace solid phase microextraction using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber at a temperature of 60 ℃. All samples were analysed using a gas chromatography- mass spectrometry system with a non-polar column, and the obtained results were discussed and compared. In almost all samples, carboxylic acids were the most prevalent, particularly hexanoic, butanoic, octanoic and acetic acid. The exception was cheese without additives, where the most abundant compound was the methyl ketone 2-nonanone. In the tested cheeses with the addition of aromatic herb extracts and dry plant material (lavender), terpenes were also identified, while no terpenes were identified in the cheese without additives. For cheeses with added extracts, the trend was observed: the higher the proportion of a particular aromatic herb extract in the cheese, the higher the proportion of terpenes
Isolation and identification of volatile compounds of jasmine : bachelor thesis
No full textU ovom završnom radu izolirani su i identificirani hlapljivi spojevi cvijeta jasmina kao i hlapljivi spojevi apsoluta i konkreta, mirisnih pripravaka dobivenih iz cvijeta jasmina. Izolacija hlapljivih spojeva izvršena je mikroekstrakcijom vršnih para na krutoj fazi (HS-SPME) korištenjem dva vlakna različitog sastava (sivog i rozog). Svi uzorci analizirani su vezanim sustavom plinska kromatografija-spektrometrija masa na HP-5MS koloni, a dobiveni rezultati su uspoređeni. U uzorcima cvijeta najzastupljeniji spoj je linalol a u uzorcima konkreta kavikol. U uzorcima apsoluta na sivom vlaknu je najzastupljeniji spoj linalol a na rozom vlaknu D-limonen.In this bachelor thesis, the volatile compounds of the jasmine flower were isolated and identified, as well as the volatile compounds of the concrete and absolute, fragrant preparations obtained from the jasmine flower. The isolation of volatile compounds was performed by solid phase microextraction (HS-SPME) using two fibres of different composition (grey and pink). All samples were analysed with a coupled gas chromatography-mass spectrometry system on a HP-5MS column, and the results were compared. In the flower samples the most abundant compound is linalool and in the concrete samples cavicol. In the absolute samples, the most abundant compound is linalool on the grey fibre and D-limonene on the pink fibre
Heat of hydration of portland cement with the addition of natural zeolite saturated with iron ions : diploma thesis
No full textU radu je određivana toplina hidratacije industrijskog portland cementa (CEM I 42,5 R) s dodatkom prirodnog zeolita zasićenog željezovim ionima i bez dodatka zeolita. Kalorimetrija je provedena tijekom prvih 48 h hidratacije diferencijalnim mikrokalorimetrom pri temperaturi od 20 °C, s omjerom voda/cement V/C = 0,5 tj. omjerom voda/kruto V/K = 0,5, a udjeli zasićenog zeolita bili su 5, 10, 20, 30 mas. %. Koristeći se računalnim programom „Hidratacija cementa“ napravljen je izračun topline hidratacije, brzine kojom se ona oslobađa te stupanj proreagiranosti uzoraka cementnog kompozita s dodatkom zasićenog zeolita i bez njega. Povećanjem udjela zasićenog zeolita smanjuju se vrijednosti topline hidratacije, smanjuje se stupanj proreagiranosti kao i brzina oslobađanja topline. Istovremeno, što je udio zasićenog zeolita veći to će se pojava pika brzine hidratacije pomaknuti prema ranijim vremenima hidratacije. Utvrđene su funkcijske ovisnosti između udjela zasićenog zeolita i ukupno oslobođene topline i vremena pojave maksimalne hidratacije.In this paper the heat of hydration of industrial Portland cement (CEM I 42.5 R) with the addition of natural zeolite saturated with iron ions and without the addition of zeolite was determined. Calorimetry was performed during the first 48 h of hydration with a differential microcalorimeter at a temperature of 20 °C, with a water/cement ratio V/C = 0.5, i.e. a water/solid ratio V/K = 0.5, and the proportion of saturated zeolite was 5, 10, 20, 30 wt. %. Using the computer program "Cement Hydration", the calculation of the heat of hydration, the rate at which it is released, and the degree of overreaction of the cement composite samples with and without the addition of saturated zeolite was made. By increasing the proportion of saturated zeolite, lower values of the heat of hydration and the degree of overreaction were registered, as well as the rate of heat release. At the same time, the higher the proportion of saturated zeolite, the more the appearance of the hydration rate peak will shift towards earlier hydration times. Functional dependencies between the proportion of saturated zeolite and the total released heat and the time of occurrence of maximum hydration were determined
THE MECHANISM OF FORMATION AND EVOLUTION OF COPPER PATINA IN DIFFERENT ENVIRONMENT : bachelor thesis
No full textU ovom radu opisuju se teorijske osnove atmosferske korozije s naglaskom na atmosfersku koroziju bakra i bakrenih legura izloženih različitom okruženju. Također, detaljno je objašnjen mehanizam i evolucija stvaranja patine kao i raznoliki kemijski sastav patine koji je povezan s parametrima iz atmosfere. Bakrene patine su kemijski i metalurški složene strukture koje se mogu prirodno ili umjetno formirati na bakru i bakrenim legurama. Osim što su estetski ugodne, izuzetno su stabilne i sprečavaju daljnju koroziju. Opisan je pregled raznih analitičkih tehnika koje su se koristile za istraživanje kemijskih, strukturnih i morfoloških svojstava patine bitnih za razumijevanje procesa korozije te za očuvanje umjetničkih i arheoloških artefakata.This paper describes the theoretical basis of atmospheric corrosion, focusing on the atmospheric corrosion of copper and copper alloys exposed to different environments. The mechanism and evolution of patina formation and the different chemical composition of the patina, which depends on the atmospheric parameters, are also explained in detail. Copper patinas are chemically and metallurgically complex structures that can form naturally or artificially on copper and copper alloys. They are not only aesthetically pleasing, but also extremely stable and prevent further corrosion. An overview is given of various analytical techniques that have been used to study the chemical, structural and morphological properties of patinas, which are important for understanding the corrosion process and for the conservation of artistic and archaeological artefacts
Influence of cadmium of glucosinolate profile in Lepidium sativum L. : master thesis
No full textGlukozinolati su sekundarni metaboliti koji se sintetiziraju iz aminokiselina. Identificirani su u preko 16 biljnih porodica, a najznačajnija je porodica Brassicaceae u koju se ubraja biljka Lepidium sativum L. Glukozinolati su kemijski i biološki neaktivni spojevi te im je zajedničko da su po kemijskoj strukturi β- tioglukozidni-N-hidroksisulfati s varijabilnim bočnim lancem. Kres salata (Lepidium sativum L.) je jednogodišnja kultura koja sadrži mnoge ljekovite tvari, ali je u ljudskoj prehrani slabo rasprostranjena. Navodi se da je kres salata dobar hiperakumulator teških metala. Biljke nemaju potrebu za kadmijem i uglavnom ne podnose koncentracije veće od 1 ppm, no navedena biljka može akumulirati kadmij u tkivima i tolerirati koncentraciju do 100 ppm. U ovom radu opisan je uzgoj biljke Lepidium sativum L. koji je zalijevan s otopinama kadmija različitih koncentracija od 1 do 50 ppm. Razvoj klica praćen je tijekom 7 dana i jedino pri koncentraciji od 50 ppm došlo je do propadanja biljke. Izolacija glukozinolata se vršila ekstrakcijom uz pomoć 70%-tnog metanola uz desulfataciju, dok se analiza vršila vezanom tehnikom UHPLC-DAD-MS/MS. Identificirani su sljedeći glukozinolati: glukotropeolin koji se nalazi u svim uzorcima i 4-metoksiglukobrasicin koji nije pronađen jedino u sjemenu. Glukotropeolin spada u skupinu arilalifatskih, dok 4-metoksiglukobrasicin pripada skupinu heterocikličnih (indolnih) glukozinolata. Sadržaj glukozinolata, s obzirom na to da su se uzorci zalijevali otopinama kadmija različitih koncentracija, nije se značajno mijenjao. U radu je također opisana priprema biljnog materijala za analizu atomskom apsorpcijskom spektroskopijom. Prije početka analiziranja potrebno je napraviti krivulju umjeravanja, zato što se preko nje iščitavaju koncentracije kadmija u biljnom materijalnu. Na temelju dobivenih rezultata izvodi se zaključak da li se biljka Lepidium sativum L. može koristiti kao hiperakumulator kadmija.Glucosinolates are secondary metabolites that are synthesized from amino acids. They were found in over 16 plant families, the most important being the Brassicaceae family, which includes the plant Lepidium sativum L. Glucosinolates are chemically and biologically inactive compounds and have in common that they are chemically β-thioglucoside-N-hydroxysulfates with a variable side chain. The Lepidium sativum L. plant is an annual crop that contains many medicinal substances, but is poorly used in the human diet. Cress salad is known to be a good hyperaccumulator of heavy metals. Plants do not need cadmium and generally do not tolerate concentrations higher than 1 ppm, but this plant can accumulate cadmium in tissues and tolerate concentrations up to 100 ppm. This thesis describes the cultivation of the plant Lepidium sativum L., which was watered with cadmium solutions of different concentrations from 1 to 50 ppm. Sprouts development was monitored for 7 days and only at a concentration of 50 ppm did the plant decay. Isolation of glucosinolate was performed by extraction with 70% methanol with desulfation, while the analysis was performed using UHPLC-DAD- MS/MS. The following glucosinolates were identified: glucotropeolin was found in all samples and 4- methoxyglucobrasicin which was not found only in seeds. Glucotropeolin belongs to the group of arylaliphatic, while 4-methoxyglucobrasicin belongs to the group of heterocyclic (indole) glucosinolates. The glucosinolate content, since the samples were watered with cadmium solutions of different concentrations, did not change significantly. The thesis also describes the preparation of plant material for analysis by atomic absorption spectroscopy. Before starting the analysis, it is necessary to make a calibration curve because the cadmium concentrations in the plant material are read through it. Based on the obtained results, it was concluded that the plant Lepidium sativum L. can be used as a hyperaccumulator of cadmium