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Synthesis and application of mesoporous cadmium doped SBA-15 for photodegradation of neonicotinoid insecticide imidacloprid
No full textPesticidi su otrovne kemikalije koje se namjerno puštaju u okoliš te onečišćuju zrak, tlo i vodu. Svaki je pesticid namijenjen uništavanju određenih nametnika, no vrlo veliki postotak dospije na neciljano odredište. Iako postoje različiti postupci za uklanjanje pesticida iz okoliša, najviše se ističu napredni oksidacijski procesi odnosno heterogena fotokataliza. Razvoj naprednih materijala za primjenu u heterogenoj fotokatalizi zahtijeva kontrolu nad sintezom i strukturnim parametrima aktivnog mjesta. Najveću pozornost, kao jedni od naprednih materijala, privukli su mezoporozni materijali od silicijevog dioksida. Oni se smatraju bitnom skupinom nanostrukturiranih potpornih materijala u heterogenoj fotokatalizi. Općenito, mezoporozni silicijev dioksid, SBA-15, ima široku primjenjivost u fotokatalizi zbog svojih relativno debljih stijenki, morfologije, kemijske stabilnosti i poroznosti što dovodi do veće toplinske i mehaničke stabilnosti. U ovom radu provedena je sinteza, karakterizacija i testiranje fotokatalitičke aktivnosti hibridnih fotokatalizatora (-SBA-15, Cd/SBA-15 i CdS/SBA-15) s ciljem smanjenja širine zabranjene zone i brzine rekombinacije parova elektron – šupljina (e-/h+) te postizanje zadovoljavajuće aktivnosti tako pripremljenih uzoraka za fotokatalitičku razgradnju imidakloprida uz primjenu UVA zračenja te provedbom reakcije u šaržnom fotoreaktoru.Pesticides are toxic chemicals that are deliberately released into the environment and pollute the air, soil, and water. Each pesticide is intended to destroy certain pests, but an exceptionally large percentage arrives at an unintended destination. Although there are different procedures for removing pesticides from the environment, advanced oxidation processes stand out the most especially heterogeneous photocatalysis. Development of advanced materials for application in heterogeneous photocatalysis requires control over synthesis and structural parameters of the active site. The greatest attention, as one of the advanced materials, have mesoporous silica materials. They are considered an essential class of nanostructured support materials in heterogeneous photocatalysis. In general, mesoporous silica, SBA – 15, has wide applicability in photocatalysis due to its relatively thicker walls, morphology, chemical stability, and porosity which leads to greater thermal and mechanical stability. In this paper, the synthesis, characterization and testing of photocatalytic activity of hybrid photocatalysts (-SBA-15, Cd/SBA-15 and CdS/SBA-15) were carried out with the aim of reducing the band gap and the rate of recombination of electron-cavity pairs (e-/h+) and achieving satisfactory activity of the thus prepared samples for the photocatalytic degradation of imidacloprid with the application of UVA radiation and by carrying out the reaction in a batch photoreactor
Extraction of piperine from different types of peppers: green solvent screening
No full textKako bi se postigli ciljevi održivog razvoja, razvoj novih zelenih otapala trenutno je u žarištu istraživanja. Zbog lakog procesa pripreme, niske cijene, potencijalne biorazgradivosti i zanemarive toksičnosti niskotemperaturna eutektička otapala (engl. Deep Eutentic Solvents (DES)) prepoznata su kao dobra zamjena organskim otapalima. Zahvaljujući sve većem interesu i razvoju niskotemperaturnih eutektičkih otapala sve se više primjenjuju kao mediji za ekstrakciju, kromatografiju te u biomedicinske svrhe u proteklih nekoliko godina. Cilj ovog rada bio je utvrditi koje niskotemperaturno eutektičko otapalo je najpogodnije za ekstrakciju piperina iz bijelog i zelenog papra. Zrna papra usitnjena su i prosijana te su dobivene tri veličinske frakcije. Piperin je nepolarna molekula te su zbog toga za ekstrakciju su pripravljena četiri hidrofobna otapala, od kojih su dva na bazi timola te dva na bazi mentola. Modelom COSMO-RS predviđena je topljivost piperina u pripremljenim otapalima te je provedena ekstrakcija sa svim veličinskim frakcijama papra. Koncentracija piperina u dobivenim uzorcima utvrđena je UV/Vis spektroskopijom, bez prethodne obrade ekstrakata. Također, disk-difuzijskim testom ispitano je antimikrobno djelovanje ekstrakata, a test toksičnosti čistih otapala proveden je pomoću bioluminiscentne bakterije Vibrio fischeri.In order to achieve the goals of sustainable development, the development of new green solvents is currently in the focus of research. Due to the easy preparation process, low price, potential biodegradability and negligible toxicity, Deep Eutentic Solvents (DES) are recognized as a good substitute for organic solvents. Thanks to the increasing interest and development of deep eutentic solvents, it is increasingly used as a medium for extraction, chromatography and for biomedical purposes in the past few years. The aim of this work was to determine which deep eutentic solvent is most suitable for the extraction of piperine from white and green pepper. The peppercorns were crushed and sieved, and three size fractions were obtained. Piperine is a non-polar molecule, which is why four hydrophobic solvents are prepared for extraction, two of them are thymol-based and two are menthol-based. The solubility of piperine in the prepared solvents was predicted by the COSMO-RS model, and extraction was performed with all size fractions of pepper. The concentration of piperine in the obtained samples was determined by UV/Vis spectroscopy, without prior processing of the extracts. Also, the antimicrobial activity of the extracts was tested with the disk diffusion test, and the toxicity test of pure solvents was performed using the bioluminescent bacterium Vibrio fischeri
Mechanochemical preparation of solid dispersions with improved drug solubility
No full textLurasidon-hidroklorid je antipsihotik koji se koristi za liječenje shizofrenije i bipolarnog poremećanja. Karakterizira ga slaba topljivost u intestinalnim fluidima, a time i slaba apsorpcija djelatne tvari u organizmu. Povećanje topljivosti lurasidon-hidroklorida, te samim time i bioraspoloživosti lijeka, znači bolje farmakološko djelovanje u liječenju psihičkih bolesti. Stoga, u ovom istraživanju, nastoji se mehanokemijski aktivirati ova djelatna tvar. Obećavajući pristup povećanju topljivosti slabo topljivih djelatnih tvari je priprava amorfnih čvrstih disperzija. U ovom radu, čvrste disperzije hidrofobnog lurasidon-hidroklorida u hidrofilnom, polimernom nosaču hidroksipropil-metil-celulozi pripravljaju se u različitim omjerima principima mehanokemije. Dobivene čvrste disperzije karakterizirane su diferencijalnom pretražnom kalorimetrijom, rendgenskom difrakcijskom analizom praha i infracrvenom spektroskopijom. U pripravi minitableta promjera 8 mm korištene su čvrste disperzije i granulirane mješavine pomoćnih tvari: manitol, natrijeva kroskarmeloza te mikrokristalna celuloza. Karakterizacija tableta uključivala je ispitivanje ujednačenosti masa te testiranje njihove raspadljivosti. Profili oslobađanja ukazuju na poboljšanu topljivost i brže oslobađanje djelatne tvari iz tableta pripravljenih iz mehanokemijskih tretiranih uzoraka u odnosu na one koje sadrže čisti netretirani lurasidon-hidroklorid.Lurasidone hydrochloride is an antipsychotic drug used for the treatment of shizophrenia and bipolar disorder. It is characterized by low solubility in intestinal fluids and thus poor absorption of drug in the organism. Solubility improvement of lurasidone hydrochloride and thus the bioavaliability of drug, means its better pharmacological response in the treatment of psychotic disorders. Therefore, in this research, there is an effort to mechanochemically activate this drug. Promising approach for solubility enhacement of poorly soluble drugs is preparation of amorphous solid dispersions. In this research, solid dispersions of hydrophobic lurasidone-hydrochloride in a hydrophilic polymer carrier hydroxypropyl methylcellulose, are to be made, in different ratios, by using principles of mechanochemistry. Obtained solid dispersions were characterized by differential scanning calorimetry, X-ray powder difraction analysis and infrared spectroscopy. Solid dispersions and granulated mixtures of excipients: mannitol, sodium croscarmellose and microcrystalline cellulose were used in the preparation of tablets with 8 mm in diameter. Characterization of tablets involved testing the mass uniforimity and its disintegration. Release profiles indicate improved solubility and faster drug release from tablets prepared from mechanochemically treated samples in comparison to those containing pure untreated lurasidone hydrochloride
Synthesis and structural characterization of 2-aryl-6-fluorobenzothiazole
No full textU ovom radu opisana je sinteza novih derivata benztiazola i njihova strukturna karakterizacija 1H-NMR i FTIR spektroskopijom. Reakcijom 2-aminotiofenola (1) i 2-amino-5-fluorotiofenola (3) s 3-fluor-4-hidroksibenzaldehidom pripravljeni su 2-(4-hidroksi-3-fluorfenil)benztiazol (4) i 2-fluor-4-(6-fluorbenzo[d]tiazol-2-il)fenol (5) koji su potom mikrovalovima potpomognutim O-alkiliranjem prevedeni u odgovarajuće derivate benztiazola (6-10). Propargiliranjem benztiazolnih derivata (4 i 5) s propargil-bromidom uz natrijev hidrid kao bazu sintetizirani su O-propargilirani derivati benztiazola 12 i 13 koji klik reakcijom kataliziranom bakrom s N-azidoetilmorfolinom (14) nisu dali ciljane 1,2,3-triazolne derivate benztiazola. Strukture svih novopripravljenih spojeva potvrđene su 1H-NMR i FTIR spektroskopijom.This paper describes the synthesis of new benzothiazole derivatives and their structural characterization by 1H-NMR and FTIR spectroscopy.
2-(4-hydroxy-3-fluorophenyl)benzothiazole (4) and
2-fluoro-4-(6-fluorobenzo[d]thiazol-2-yl)phenol (5) were prepared by reaction of 2-aminothiophenol (1) and 2-amino-5-fluorothiophenol (3) with
3-fluoro-4-hydroxybenzaldehyde, which were then converted under microwave irradiation into the corresponding benzothiazole derivatives (6-10). Propargylation of benztohiazole derivatives (4 and 5) with propargyl bromide using sodium hydride as a base gave O-propargylated benzothiazole derivatives 12 and 13, which didn't give by copper catalysed click reaction with ethylmorpholine azide (14) desired 1,2,3-triazole derivatives of benzothiazole 15 and 16. The structures of all newly prepared compounds were confirmed by 1H-NMR and FTIR spectroscopy
Preparation of ceramic monolithic catalyst for catalytic oxidation of BTEX
No full textZbog sve većih i učestalijih emisija iz brojnih industrijskih, ali i ostalih izvora emisija, zagađenje zraka postaje sve veći problem koji se prioritetno razmatra u okviru ukupne strategije zaštite okoliša. Hlapljivi organski spojevi koji pri normalnim uvjetima tlaka i temperature vrlo lako isparavaju predstavljaju jednu od najznačajnijih skupina spojeva koji uzrokuju onečišćenje atmosfere. Najznačajniji predstavnici aromatskih hlapljivih organskih spojeva su benzen, toluen, etilbenzen te izomeri ksilena (o-ksilen, m-ksilen i p-ksilen), koji uobičajeno dolaze pod zajedničkim nazivom BTEX. S obzirom na to da su lako hlapljivi, a sastavni su dio brojnih proizvoda koji su svakodnevno u upotrebi, sve se više istražuje njihov učinak na ljudsko zdravlje. Postoje brojne metode kojima se nastoji spriječiti emisija BTEX spojeva u okoliš, pri čemu se katalitička oksidacija pokazala vrlo učinkovitim načinom razgradnje navedenih spojeva. Cilj ovog diplomskog rada je priprema keramičkih monolitnih katalizatora za katalitičku oksidaciju BTEX spojeva. Ispitana je mogućnost primjene cirkonijeva dioksida (ZrO2) kao filamenta za izradu 3D-ispisanih keramičkih monolitnih nosača, pri čemu je primijenjena proizvodnja rastaljenim filamentom koja pripada tehnikama aditivne proizvodnje. Također, korištene su dostupne metode karakterizacije cirkonijeva dioksida u svrhu dobivanja što boljeg uvida u svojstva materijala. Kao katalitički aktivan sloj korišten je miješani oksid mangana i željeza, odnosno MnFeOx, a njegovo nanošenje na monolitni nosač provedeno je metodom mokre impregnacije. Zbog nepravilne i kompleksne geometrije, određena je približna geometrijska površina dobivenog nosača koja iznosi
53,4 cm^2, dok je masa nanesenog katalitički aktivnog sloja 50,3 mg. Aktivnost pripremljenih monolitnih katalizatora za oksidaciju BTEX-a ispitana je pri različitim temperaturama i prostornim vremenima. Dobiveni rezultati uspoređeni su s rezultatima dobivenim primjenom keramičkih kordijeritnih monolitnih katalizatora s različitim dimenzijama kanala te s monolitnim katalizatorima izrađenim postupkom stereolitografije. U završnom dijelu rada provedena je kinetička analiza i modeliranje monolitnog reaktora, pri čemu su eksperimentalni rezultati uspoređeni s teorijskim rezultatima dobivenim primjenom 1D pseudohomogenog i
1D heterogenog modela, pri čemu su izvedeni odgovarajući zaključci.Due to increasing and more frequent emissions from numerous industrial and other sources, air pollution is becoming a growing problem, which is given priority in the overall environmental protection strategy. Volatile organic compounds, which easily evaporate under normal pressure and temperature conditions, represent one of the most significant groups of compounds causing atmospheric pollution. The most significant representatives of aromatic volatile organic compounds are benzene, toluene, ethylbenzene, and xylenes isomers
(o-xylene, m-xylene, and p-xylene), commonly referred to as BTEX. Since they are highly volatile and are part of numerous products used daily, their impact on human health is being increasingly investigated. There are various methods aimed at preventing the emission of BTEX compounds into the environment, with catalytic oxidation proving to be a highly effective way of degrading these compounds. The aim of this work is to prepare ceramic monolithic catalysts for the catalytic oxidation of BTEX compounds. The possibility of using zirconium dioxide (ZrO2) as a filament for the production of 3D-printed ceramic monolithic supports was examined, employing the production with the molten filament, which belongs to additive manufacturing techniques. Additionally, available characterization methods of zirconium dioxide were used to gain a better insight into the material's properties. The catalytically active layer used was a mixed manganese and iron oxide, MnFeOx, and its application to the monolithic support was carried out by the impregnation method. Due to the irregular and complex geometry, the approximate geometric surface area of the obtained support was determined to be 53.4 cm^2, while the mass of the applied catalytically active layer was 50.3 mg. The activity of the prepared monolithic catalysts for the oxidation of BTEX was tested at different temperatures and space times. The obtained results were compared with the results obtained using ceramic cordierite monolithic catalysts with different channel dimensions, as well as with monolithic catalysts made by stereolithography. In the last part of the work, a kinetic analysis and modeling of the monolithic reactor were carried out, comparing the experimental results with the theoretical results obtained with the
1D pseudohomogeneous and 1D heterogeneous models, and drawing appropriate conclusions
The influence of multiple extrusion on the crystal structure of polypropylene
No full textPlastični se otpad radi povećanja proizvodnje i potrebe za plastikom sve češće može pronaći u okolišu. Njegovom degradacijom dolazi i do formiranja mikroplastike (MP), plastičnih fragmenata manjih od pet milimetara. Ona se lako prenosi kroz prirodu putem vjetra i voda, ali i kroz hranidbeni lanac pa tako predstavlja opasnost za neživi dio okoliša, floru, faunu te, naposlijetku, ljude. Cilj ovog rada bio je proučiti utjecaj višestrukog ekstrudiranja na uzroke polipropilena, termoplastičnog polimernog materijala. Mehaničko recikliranje polipropilena provedeno je na dvopužnom laboratorijskom ekstruderu, a granule su ekstrudirane pri temperaturnom profilu ekstrudera T = 170/190/190/195/200/200 °C pri brzini vrtnje pužnog vijka od 50 rpm u četiri ciklusa. Uzorci dobiveni ekstrudiranjem karakterizirani su infracrvenom spektroskopijom te rentgenskom difrakcijom (XRD). Infracrvena spektroskopija (FTIR) daje informacije o razgradnji uzorka, odnosno pojavi i/ili nestanku karakterističnih funkcionalnih skupina molekule polipropilena, a rentgenskom difrakcijom se utvrđuje strukturna uređenost kristala (homogenost, kristalnost). Višestrukim recikliranjem uzoraka polipropilena dolazi do pojave novih degradacijskih skupina koje sadrže kisik, a s povećanjem broja ciklusa ekstrudiranja one se rekombiniraju i/ili nestaju. Također, s povećanjem broja ciklusa ekstrudiranja, smanjuje se koncentracija degradacijskih skupina i kristalnost uzoraka, koji su u procesu ostali homogeni.Plastic waste is increasingly found in the environment due to the growing production and demand for plastics. Its degradation leads to the formation of microplastics (MPs), plastic fragments smaller than five millimeters. Microplastics are easily transported through nature via wind and water, and they can also enter the food chain, posing a threat to the non-living environment, flora, fauna, and ultimately, humans. The aim of this study was to investigate the impact of multiple extrusion processes on the properties of polypropylene, a thermoplastic polymer material. Mechanical recycling of polypropylene was carried out using a twin-screw laboratory extruder, and the pellets were extruded at an extruder temperature profile of T = 170/190/190/195/200/200 °C with a screw rotation speed of 50 rpm in four cycles. Samples obtained through extrusion were characterized using infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Infrared spectroscopy provided information about the degradation of the samples, including the appearance and/or disappearance of characteristic functional groups in the polypropylene molecule. X-ray diffraction was used to determine the structural and the fraction of crystallinity (homogeneity, crystallinity). Multiple recycling cycles of polypropylene samples resulted in the emergence of new oxygen-containing degradation groups, which combined and/or disappeared with an increasing number of extrusion cycles. Additionally, as the number of extrusion cycles increased, the concentration of degradation groups and the crystallinity of the samples that remained homogeneous during the process decreased
Thermodynamic aspects of natural gas liquefaction and regasification processes at the LNG terminal
No full textZemni plin, poznatiji pod nazivom prirodni plin, plinska je smjesa ugljikovodika koja se pretežito sastoji od metana (CH4) s manjim udjelima etana (C2H6), propana (C3H8) i viših ugljikovodika. Često u svojem sastavu posjeduje i male količine ugljikovog dioksida (CO2), dušika (N2), vode (H2O) i sumporovodika (H2S), a ponekad i helij (He). Zemni plin je plin bez boje i mirisa, zapaljiv je i netoksičan te se svrstava u primarne oblike energije. Također je i konvencionalan neobnovljiv energent koji nastaje raspadom slojeva organske tvari unutar stijena pri određenim dubinama Zemljine kore u anaerobnim uvjetima što rezultira porastom tlaka i temperature te iste. Ovaj proces nije brz te se odvija milijunima godina. Energija koju su raspadnuti organizmi dobili od Sunca putem procesa fotosinteze pohranjuje se kao kemijska energija unutar molekula metana i drugih ugljikovodika čiji se potencijal iskorištava u druge svrhe. Kako bi zemni plin imao komercijalnu primjenu, on se mora podvrgnuti raznim procesima: od izvlačenja iz nalazišta, rafinerijske obrade i pročišćavanja pa do ukapljivanja, skladištenja, ponovnog uplinjavanja te transporta do potrošača. U ovom radu biti će dan kratak pregled sustava transporta prirodnog plina od nalazišta do potrošača. Također će se opisati i objasniti pojedini procesi ukapljivanja i ponovnog uplinjavanja prirodnog plina na LNG terminalima te će se usporediti procesi koji su danas najčešći u primjeni. Prikazat će se i analizirati pojedini podaci koji će upućivati na mogućnosti poboljšanja ovih procesa s ciljem povećanja ukupne energetske učinkovitosti. U nastavku rada će se za „zemni plin“ koristiti pojam „prirodni plin“ koji će posjedovati kraticu „PP“. Razlog tomu je što je naziv „prirodni plin“ češće primjenjivan u svakidašnjici.Natural gas is a gas mixture of hydrocarbons that mainly consists of methane (CH4) with smaller proportions of ethane (C2H6), propane (C3H8) and higher hydrocarbons. It often contains small amounts of carbon dioxide (CO2), nitrogen (N2), water (H2O) and hydrogen sulfide (H2S), and sometimes helium (He). Natural gas is a colourless and odourless gas, it is flammable and non-toxic, and it is classified as a primary form of energy. It is also a conventional non-renewable energy source that is created by the breakdown of layers of organic matter inside rocks at certain depths of the Earth's crust in anaerobic conditions, which results in an increase in pressure and temperature of the Earth's crust. This process is not fast and takes place over millions of years. The energy that decomposed organisms received from the Sun through the process of photosynthesis is stored as chemical energy within the molecules of methane and other hydrocarbons, the potential of which is used for other purposes. In order for natural gas to be used commercially, it must undergo various processes: from extraction from deposits, refinery processing and purification to liquefaction, storage, regasification and transport to consumers. In this paper, a brief overview of the natural gas transportation system from the gas field to the consumer will be given. It will also describe and explain individual processes of liquefaction and regasification of natural gas at LNG terminals, and compare the processes that are most commonly used today. Some data will be presented and analysed that will point to the possibilities of improving these processes with the aim of increasing overall energy efficiency
Radioactivity
No full textZračenje i radioaktivni materijali dio su okoliša. Zračenje u okolišu dolazi od kozmičkog zračenja koje potječe iz svemira i od radioaktivnih materijala koji se prirodno pojavljuju u zemlji i u ljudskim tijelima. Radioaktivnost se odnosi na čestice koje se emitiraju iz jezgri kao rezultat nuklearne nestabilnosti. Različite vrste radioaktivnosti dovode do različitih puteva raspada koji pretvaraju jezgre u druge kemijske elemente. Mnoge su dobrobiti, ali i opasnosti radioaktivnog zračenja. Opasnosti radioaktivnog zračenja najbolje prikazuje Černobilska katastrofa. Dana 26. travnja 1986., operateri u kontrolnoj sobi reaktora 4 u nuklearnoj elektrani Černobil počinili su kobnu seriju pogrešaka tijekom sigurnosnog testa, što je izazvalo topljenje reaktora koje je rezultiralo najvećom svjetskom nuklearnom nesrećom do danas.Radiation and radioactive materials are part of the environment. Radiation in the environment comes from cosmic radiation that originates in space and from radioactive materials that occur naturally in the earth and in human bodies. Radioactivity refers to particles emitted from nuclei as a result of nuclear instability. Different types of radioactivity lead to different decay pathways that convert nuclei into other chemical elements. There are many benefits, but also dangers of radioactive radiation. The dangers of radioactive radiation are best illustrated by the Chernobyl disaster. On April 26, 1986, operators in the control room of Reactor 4 at the Chernobyl nuclear power plant committed a fatal series of errors during a safety test, causing the reactor to meltdown resulting in the world's worst nuclear accident to date
Application of differential scanning calorimetry in the characterization of biogenic material
No full textPorast štetnih životnih navika uzrokuje sve veći broj jetrenih oboljenja što povećava potrebu za transplantacijom ili popravkom oštećenog tkiva. Decelularizacija prirodnih tkiva obećavajuća je metoda za dobivanje trodimenzionalne mreže za regeneraciju tkiva jer se zadržavaju prirodna struktura i komponente što predstavlja bitni čimbenik za preživljavanje stanica. Vrlo je bitno razviti metodu decelularizacije koja će dovoljno dobro ukloniti stanice, a opet sačuvati komponente izvanstanične matrice. Za decelularizaciju jetrenog tkiva korištena su dva detergenta, natrijev lauret sulfat (SLES) i natrijev lauril sulfat (SDS). U protokolima decelularizacije ispitan je utjecaj vremena izmjene medija i koncentracije detergenata te je uključena i dodatna obrada ultrazvukom u trajanju od 1, 2, 4 i 8 sati. U uzorcima su nakon decelularizacije kvantificirane biološke komponente: DNK, kolagen i glikozaminoglikani. Uzorci su nakon decelularizacije podvrgnuti digestiji te liofilizaciji. Razlikovna pretražna kalorimetrija provedena je na uzorcima nakon decelularizacije i digestije te su utvrđene vrijednosti normalizirane entalpije te početne i maksimalne temperature denaturacije. Dobiveni rezultati pokazuju da je uzorak SDS 1a, obrađen natrijevim lauril sulfatom koncentracije 1 % s vremenom izmjene medija 30 minuta, najpogodniji za daljnja ispitivanja primjene u 3D tisku. Unatoč literaturnim podacima koji ukazuju na povezanost entalpije i temperatura denaturacije s udjelom kolagena, u provedenim mjerenjima nije uočena direktna povezanost što može biti posljedica prisutnosti drugih tvari osim kolagena.The prevalence of unfavorable lifestyle habits is leading to a growing incidence of liver disease, increasing the need for transplantation or repair of damaged tissue. Decellularization of natural tissue is a promising method to maintain a three-dimensional network for tissue regeneration, as the natural structure and components are preserved, which is an essential factor for cell survival. It is of utmost importance to develop a decellularization method that removes the cells well enough and still preserves the components of the extracellular matrix. Two detergents have been used for decellularization of liver tissue – sodium laureth sulfate (SLES) and sodium lauryl sulfate (SDS). In the decellularization protocols, the influence of medium exchange time and detergent concentration was investigated and additional ultrasound treatment was included for 1, 2, 4, and 8 hours. After decellularization, the biological components in the samples were quantified: DNA, collagen, and glycosaminoglycans. After decellularization, the samples were subjected to a digestion process and freeze-dried. After decellularization and digestion, the samples were subjected to differential scanning calorimetry and the values of normalized enthalpy and initial and maximum denaturation temperatures were determined. The results obtained show that the sample SDS 1a, treated with sodium lauryl sulfate at a concentration of 1% with a medium change of 30 minutes, is the most suitable for further testing for application in 3D printing. Despite evidence of a relationship between enthalpy and denaturation temperatures with collagen content, no direct relationship was found in the measurements, which could be due to the presence of substances other than collagen
Biodegradation of TPS/PLA blends
No full textPrimjena polimernih materijala je danas postala nezaobilazna potreba u raznim sektorima industrije i poljoprivrede. Pretjerana potrošnja materijala na bazi nafte, koja dovodi do iscrpljivanja prirodnih resursa, potaknula je znanstvenike na istraživanje novih biorazgradljivih materijala koji se mogu koristiti za razne potrebe industrije. Biorazgradljivi materijali imaju sposobnost razgradnje u okolišu pod utjecajem mikroorganizama, vode, kisika i sunčeve svjetlosti. Osim pozitivnog utjecaja na okoliš, određeni biorazgradljivi materijali poput termoplastičnog škroba (TPS) su ekonomski povoljni zbog svoje pristupačnosti, dostupnosti i sposobnosti da smanje ovisnost tržišta o cijenama plastike koje diktira naftna industrija. U ovom je istraživanju ispitana biorazgradljivost polimernih mješavina koje se sastoje od termoplastičnog škroba i polilaktida (PLA), sa i bez dodatka limunske kiseline (LK). Ispitivanje je provedeno u skladu sa standardima ISO 14855 i ASTM D5338. Identifikacija i karakterizacija TPS/PLA mješavina koje su biorazgradljive temeljito su provedene korištenjem infracrvene spektrometrije s Fourierovim transformacijama
(FTIR-ATR). Morfologija polimernih mješavina analizirana je pomoću skenirajuće elektronske mikroskopije (SEM). Uzorci su promatrani prije i poslije procesa biorazgradnje svjetlosnim mikroskopom i optičkim mikroskopom s polarizacijom zbog uvida u površinsku strukturu materijala. Praćena je i promjena mase tijekom 56 dana procesa biorazgradnje.The application of polymeric materials has become an indispensable need in various sectors of industry and agriculture. Excessive consumption of petroleum-based materials, which leads to the depletion of natural resources, has prompted scientists to explore new biodegradable materials that can be used for the various needs of the industry. Biodegradable materials have the ability to decompose in the environment under the influence of microorganisms, water, oxygen and sunlight. In addition to the positive impact on the environment, certain biodegradable materials such as thermoplastic starch (TPS) are economically advantageous due to their affordability, availability and ability to reduce the market's dependence on plastic prices dictated by the oil industry. In this study, the biodegradability of polymer mixtures consisting of thermoplastic starch and polylactide (PLA), with and without the addition of citric acid (LK), was examined. The test was conducted in accordance with ISO 14855 and ASTM D5338 standards. The identification and characterization of TPS/PLA mixtures that are biodegradable was thoroughly carried out using Fourier transform infrared spectrometry (FTIR-ATR). The morphology of polymer mixtures was analyzed using scanning electron microscopy (SEM). Samples were observed before and after the biodegradation process by light microscope and optical microscope with polarization for insight into the surface structure of the material. A change in mass during the 56 days of the biodegradation process was also monitored