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Preparation of polymer nanocomposites with cellulose and functional amino methacrylates
No full textKao i brojne druge svjetske industrije, kemijska industrija u novije doba napušta uporabu fosilnih sirovina kako zbog saznanja o njihovoj ograničenosti tako i zbog povećane svijesti o njihovom štetnom utjecaju na okoliš. Zbog toga je jedna od glavnih zadaća ,,zelene kemije'' pronalazak ,,zelenih alternativa'', no one moraju zadovoljavati svojstva koja su do tada imali materijali dobiveni iz fosilnih sirovina te pritom trebaju biti ekonomski isplativi kako bi se mogli koristiti u široj upotrebi. Također, trebaju se pronaći i povoljna zelena otapala koja će zamijenti štetna organska otapala. Općeniti cilj priprave ekološki prihvatljivih polimera i kompozita je zamijeniti udio fosilnog sintetskog dijela nanokompozita s obnovljivom sastavnicom koja je povoljnija za okoliš, a u ovom radu pokušat će se zamijeniti čak
50 mas. % fosilnog sintetskog polimera obnovljivim biopunilom - celulozom. Celulozni nanokristali osim svojeg bio-podrijetla, imaju veliku specifičnu površinu i udio kristalnosti, male su mase te su nanometarskih veličina što ih čini vrlo poželjnim u primjeni prilikom pripreme polimernih nanokompozita.
U radu su ispitana svojstva čistih kopolimera metil-metakrilata (MMA) s 2-(diizopropil-amino)etil metakrilatom (DPA) ili 2-(dimetilamino)etil metakrilatom (DMAEMA) ili 2-N-morfolinoetil metakrilatom (NMPEM) u udjelima od 10 mol. % kao i njihovih nanokompozita s celuloznim nanokristalima u udjelima od 1, 5, 10, 15, 20 i 50 mas.%. Kopolimerizacije su provedene u zelenom otapalu, dihidrolevoglukozenonu poznatijem pod nazivom Cyrene™. Obzirom da je Cyrene™ dobiven pirolizom iz biomase celuloze, kao punilo odabrala se upravo celuloza zbog očekivane dobre disperzije u matrici. Ispitana su toplinska i mehanička svojstva polimernih nanokompozita te raspodjela molekulskih masa kopolimera. Sinteze kopolimera i kompozita uspješno su provedene do visokih konverzija monomera, te su dobiveni uzorci velike molekulske mase kopolimera, osobito za kopolimere s DPA i NMPEM. Za ove sustave rezultirale su i široke raspodjele molekulskih masa koje nisu potpuno unimodalne, vjerojatno zbog izraženog gel efekta tijekom polimerizacije. Utvrđeno je da se temperature staklastog prijelaza povećavaju s udjelom celuloznih nanokristala kod kompozita s DMAEMA, dok se kod drugih smanjuju, vjerojatno zbog nepovoljnih molekulskih međudjelovanja, osim za najveće udjele nanoceluloze od 20 i 50 mas. %. Dodatkom celuloznih nanokristala kopolimeru s NMPEM mehanička svojstva se blago poboljšavaju, dok za one s DPA i DMAEMA vrijedi suprotno, osim za najmanje udjele nanoceluloze.Like many other global industries, the chemical industry in recent times is moving away from the use of fossil resources due to their limited availability and the increased awareness of their harmful impact on the environment. Therefore, one of the main tasks of "green chemistry" is to find "green alternatives," but these alternatives must meet the properties that materials obtained from fossil resouces had so far and must also be economically viable for broader use. Additionally, it is necessary to find favorable green solvents to replace harmful organic solvents. The general goal of preparing environmentally friendly polymers and composites is to replace the portion of fossil synthetic components in nanocomposites with a more environmentally friendly renewable component. In this work, an attempt will be made to replace as much as 50% by weight of fossil synthetic polymer with renewable bioreinforcement - cellulose. Cellulose nanocrystals, in addition to their bio-origin, have a large specific surface area and crystallinity, low weight, and nanometer-sized dimensions, making them highly desirable for use in the preparation of polymeric nanocomposites.
The properties of pure copolymers of methyl methacrylate (MMA) with 2-(diisopropylamino)ethyl methacrylate (DPA) or 2-(dimethylamino)ethyl methacrylate (DMAEMA) or 2-N-morpholinoethyl methacrylate (NMPEM) at 10 mol.% were investigated, as well as their nanocomposites with cellulose nanocrystals at 1, 5, 10, 15, 20, and 50 wt.%. The copolymerizations were carried out in a green solvent, dihydrolevoglucosenone, better known as Cyrene™. Since Cyrene™ is derived from biomass cellulose through pyrolysis, cellulose was chosen as the filler due to the expected good dispersion in the matrix.
The thermal and mechanical properties of polymeric nanocomposites were examined, as well as the molecular weight distribution of the copolymers. The synthesis of copolymers and composites was successfully carried out to high monomer conversions, and samples of high molecular weight copolymers were obtained, especially for copolymers with DPA and NMPEM. For these systems, broad molecular weight distributions that were not entirely unimodal were observed, likely due to the pronounced gel effect during polymerization. It was found that the glass transition temperatures increase with the cellulose nanocrystal content in the DMAEMA composites, while they decrease in other cases, probably due to unfavorable molecular interactions, except for the highest cellulose nanocrystal content of 20 and 50 wt.%.
The addition of cellulose nanocrystals to the NMPEM copolymer slightly improves the mechanical properties, while the opposite is true for DPA and DMAEMA, except for the lowest cellulose nanocrystal content
Disinfection processes of water treatment
No full textU ovom radu opisani su dezinfekcijski procesi obrade voda pomoću klora, kloramina, ozona, klorovog dioksida i ultraljubičastog (UV) zračenja. Dezinfekcija voda provodi se u svrhu uklanjanja onečišćivala poput bioloških, mineralnih i organskih nečistoća, radioaktivnosti, induciranog zagađenja, te smanjenja koncentracija elemenata poput Fe, Mn i H2S koji premašuju dogovorenu granicu normi. Cilj dezinfekcije pitke vode i vode za kućnu upotrebu je uspostavljanje nacionalnih standarda koje je preporučila Svjetska zdravstvena organizacija (SZO). Prilikom dezinfekcije vode nastaju nusprodukti koji mogu biti štetni za zdravlje ljudi, te je iz tog razloga potrebno poboljšati metode dezinfekcije voda.This paper describes the disinfection processes of water treatment using chlorine, chloramines, ozone, chlorine dioxide and ultraviolet (UV) radiation. Water disinfection is carried out for the purpose of removing pollutants such as biological, mineral and organic impurities, radioactivity, induced pollution and reducing the concentration of elements such as Fe, Mn and H2S that exceed the agreed upon norms. The goal for disinfecting drinking water and water for domestic use is to establish national standards recommended by the World Health Organization (WHO). By-products are created during the disinfection process and they can be harmful for people and so for that reason it is necessary to improve the methods of water disinfection
Vibrational analysis of amino acids
No full textOvaj rad bavi se vibracijskom analizom aminokiselina pomoću infracrvene (IR) spektroskopije i teorijskih proračuna u programu Gaussian 09. Cilj istraživanja bio je usporediti teorijske IR spektre s eksperimentalnim podacima iz literature kako bi se identificirali ključni vibracijski modovi i utvrdio utjecaj okoline na vibracijska svojstva molekula. Analizirane su tri aminokiseline – glicin, histidin i asparaginska kiselina. Uočene su značajne razlike između spektara snimljenih u različitim uvjetima, posebno između teorijskih spektara izračunatih u vakuumu i eksperimentalnih spektara dobivenih u vodenoj otopini ili čvrstom stanju. Rezultati su pokazali da interakcije s molekulama vode putem vodikovih veza značajno utječu na pomake i intenzitet vibracijskih vrpci, posebno u području stretching vibracija O-H, N-H i C=O veza. Usporedba eksperimentalnih i teorijskih spektara pokazala je da Gaussian 09 precizno modelira vibracijske modove, iako teorijske frekvencije često odstupaju od eksperimentalnih zbog idealiziranih uvjeta modeliranja. Unatoč tome, skaliranjem frekvencija moguće je postići bolje slaganje s eksperimentalnim podacima. Zaključno, ovaj rad potvrđuje važnost kombinacije teorijskih i eksperimentalnih metoda u karakterizaciji aminokiselina te naglašava značaj okoline u određivanju njihovih spektroskopskih svojstava.This paper focuses on the vibrational analysis of amino acids using infrared (IR) spectroscopy and theoretical calculations performed with the Gaussian 09 program. The aim of the study was to compare theoretical IR spectra with experimental data from the literature to identify key vibrational modes and determine the influence of the environment on the vibrational properties of molecules. Three amino acids—glycine, histidine, and aspartic acid—were analyzed. Significant differences were observed between spectra recorded under different conditions, particularly between theoretical spectra calculated in a vacuum and experimental spectra obtained in aqueous solution or solid-state form. The results showed that interactions with water molecules through hydrogen bonding significantly affect shifts and intensities of vibrational bands, especially in the region of stretching vibrations of O-H, N-H, and C=O bonds. The comparison of experimental and theoretical spectra demonstrated that Gaussian 09 accurately models vibrational modes, although theoretical frequencies often deviate from experimental ones due to the idealized modeling conditions. Nevertheless, frequency scaling can improve agreement with experimental data. In conclusion, this study confirms the importance of combining theoretical and experimental methods in the characterization of amino acids and highlights the significance of the environment in determining their spectroscopic properties
Starenje baterija: empirijski pristup i pristup tehnikama strojnog učenja
No full textSuccessful prediction of lithium-ion battery ageing could help address numerous safety, environmental, and economic challenges. This master’s thesis develops and compares three different machine learning models for predicting charging profiles and battery health (State of Health, SoH, defined as the relative reduction of maximum capacity compared to the capacity recorded during the first charge) throughout ageing cycles. The machine learning models employed are Long Short-Term Memory (LSTM) model, a tree-based model XGBoost, and a transformer model. The models were trained using data from commercial Kokam SLPB 533459H lithium-ion pouch cells (LCO-NCO cathode, graphite anode) cycled under Artemis driving profiles at 40 °C. A hyperparameter tuning approach was applied to each model to ensure optimal performance, and performance was evaluated using several metrics, including mean squared error (MSE), root mean squared error (RMSE), coefficient of determination (R²), Pearson correlation coefficient, and mean absolute error (MAE). All models demonstrated excellent predictive capability on the test portion of Cell1 dataset (R² > 0,99), with XGBoost achieving the highest accuracy (R² > 0,999). When the developed models were applied to a new cell (Cell2) exhibiting a different capacity degradation trend toward the end of cell life (after SoH ≈ 80 %), model performance significantly decreased, with the LSTM model showing the smallest deterioration in results (154 % increase in MSE; in comparison, MSE increased 184 % for the transformer model and 1755 % for the XGBoost model). This indicates that models trained on cells with gradual, consistent degradation fail to generalize to cells exhibiting different degradation patterns. The study demonstrates the capability of machine learning methods to predict charging profiles and battery health during typical ageing conditions. It also highlights the need for training on diverse datasets that include various degradation patterns, especially at the end of life, in order to develop more robust models capable of predicting irregular capacity changes.Uspješno predviđanje starenja litij-ionskih baterija može značajno doprinijeti rješavanju brojnih sigurnosnih, ekoloških i ekonomskih izazova. U ovom diplomskom radu razvijena su i međusobno uspoređena tri različita modela strojnog učenja u svrhu predviđanja profila punjenja i zdravlja baterije (eng. State of Health, SoH), definiranog kao relativno smanjenje maksimalnog kapaciteta u n-tom ciklusu punjenja u odnosu na početni maksimalni kapacitet. Razvijeni su modeli duge kratkoročne memorije (LSTM), model temeljen na stablima odlučivanja (XGBoost) te transformer model. Modeli su trenirani koristeći podatke komercijalnih Kokam SLPB 533459H litij-ionskih vrećastih ćelija (LCO-NCO katoda, grafitna anoda) punjenih i pražnjenih pod Artemis voznim profilima pri temperaturi od 40 °C. Za svaki model proveden je postupak podešavanja hiperparametara, a učinkovitost modela je procijenjena pomoću više evaluacijskih metrika: srednje kvadratne pogreške (MSE), korijena srednje kvadratne pogreške (RMSE), koeficijenta determinacije (R²), Pearsonove korelacije i srednje apsolutne pogreške (MAE). Svi razvijeni modeli pokazali su izvrsnu prediktivnu sposobnost na testnom dijelu podataka ćelije 1 (Cell1) (R² > 0,99), pri čemu je XGBoost postigao najveću točnost (R² > 0,999). Međutim, kada su razvijeni modeli primijenjeni na novu ćeliju (Cell2) koja je pri kraju životnog vijeka pokazivala izraženiji i drugačiji trend starenja (nakon SoH ≈ 80 %), učinkovitost svih modela značajno se smanjila. Najmanje pogoršanje rezultata pokazao je LSTM model (povećanje MSE od 154 %; za usporedbu, pogoršanje MSE kod transformer modela bilo je 184 %, te kod XGBoost modela 1755 %) što ukazuje na njegovu bolju sposobnost generalizacije na nestandardne obrasce degradacije. Modeli trenirani na ćelijama s postupnom i konzistentnom degradacijom nisu se u potpunosti uspješno generalizirali na ćelije s drugačijim obrascima starenja. U radu je potvrđena sposobnost strojnog učenja za predviđanje profila punjenja te praćenje zdravlja baterija tijekom uobičajenog procesa starenja. Također je istaknuta potreba za treniranjem modela na raznolikim skupovima podataka koji obuhvaćaju različite obrasce degradacije, posebice one karakteristične za kraj životnog vijeka kako bi se razvili robusniji modeli sposobni predviđati nepravilne i ubrzane promjene kapaciteta
Decorating of nanostructured zincite films with CdSe quantum dots
No full textMogućnost manipulacije svojstava materijala pomoću nanotehnologije na jako maloj skali otvara brojne prilike. Nanostrukturirani ZnO posjeduje odlična kemijska, električna i optička svojstva zbog čega svoju primjenu pronalazi u optoelektroničkim uređajima, solarnim ćelijama, senzorima i još mnogim novim tehnologijama. Također, njegova svojstva se mogu poboljšati dopiranjem ili dekoriranjem česticama poluvodiča nano veličina odnosno kvantnim točkama što dodatno proširuje njegovu primjenu. Cilj ovog rada bio je pripremiti tanke cinkitne (ZnO) filmove te ih dekorirati CdSe kvantnim točkama. ZnO filmovi pripremljeni su metodom oblaganja rotiranjem. CdSe kvantne točke su sintetizirane iz prekusorskih otopina te su nanesene na prethodno pripremljene ZnO filmove metodom drop casting-a i metodom oblaganja rotiranjem. Za detaljnu analizu uzoraka korištene su mikroskopija atomskih sila, rendgenska difrakcija i UV/Vis spektrometrija. Dobiveni rezultati pružaju uvid u primjenjivost korištenih metoda i materijala u sintezi filmova koji se mogu koristiti u solarnim ćelijama.The ability of nanotechnology to manipulate materials on a very small scale opens up numerous opportunities. Nanostructured ZnO has excellent chemical, electrical and optical properties, which is why it finds its application in optoelectronic devices, solar cells, sensors and many other advanced technologies. In addition, its properties can be improved by doping or decorating it with nano-sized semiconductor particles or quantum dots, which further expands its application. The aim of this work was to prepare thin zincite (ZnO) films and decorate them with CdSe quantum dots. ZnO films were prepared by the spin coating method. CdSe quantum dots were synthesized from precursor solutions and were applied to previously prepared ZnO films by drop casting and spin coating methods. Atomic force microscopy, X-ray diffraction and UV/Vis spectrometry were used for detailed analysis of the samples. The obtained results provide insight into the applicability of the used methods and materials in the synthesis of films that can be used in solar cells
Design and 3D printing of a microreactor with integrated FTIR probe for fatty acid methyl ester production
No full textAditivna proizvodnja, poznata i kao 3D-ispis, predstavlja suvremenu tehnologiju izrade trodimenzionalnih objekata sloj po sloj. U ovom radu korištena je tehnologija proizvodnje rastaljenim filamentom (FFF), kojom su izrađeni mikroreaktori od PET-G materijala. Cilj rada bio je dizajnirati i ispisati mikroreaktore, ispitati njihovu učinkovitost te integrirati FTIR sondu u sustav radi praćenja kemijske reakcije u stvarnom vremenu. U ovom radu uspješno je provedena sinteza biodizela reakcijom transesterifikacije. Ispitana je i kemijska stabilnost
PET-G materijala putem testa bubrenja u suncokretovom ulju, metanolu, smjesi metanola i KOH te biodizelu. Najveća stabilnost zabilježena je u suncokretovom ulju, dok je u smjesi metanola i KOH došlo do potpunog otapanja uzoraka pri 50 i 60 °C već nakon 15 minuta. Sinteza biodizela provedena je šaržno i u četiri različita mikroreaktora: ravnom cijevnom te cijevnim s 4, 8 i 12 koljena. Konverzija reakcije praćena je FTIR sondom integriranom u sustav, snimanjem spektara svakih 5 minuta. Izrađen je baždarni dijagram na temelju karakteristične vrpce pri 1099 cm⁻¹, koji je omogućio kvantitativno određivanje konverzije. Rezultati su pokazali da su mikroreaktori s 0, 8 i 12 koljena postigli slične vrijednosti konverzije, dok su se u reaktoru s 4 koljena ostvarile niske konverzije, čime je on pokazao i najslabiju učinkovitost. FTIR analiza provedena je pomoću FTIR sonde i dvaju spektrofotometara (PerkinElmer i Shimadzu). Usporedbom spektara utvrđeno je da su svi pouzdano detektirali karakteristične vrpce reaktanata i produkata, iako je sonda pokazala nešto slabiji intenzitet vrpci i lošiji odnos signala i šuma. FTIR sonda uspješno je integrirana te je omogućila kontinuirano praćenje reakcije u stvarnom vremenu.Additive manufacturing, also known as 3D printing, is a modern technology for creating threedimensional objects layer by layer. In this work, fused filament fabrication (FFF) was used to produce microreactors made from PET-G material. The aim of the study was to design and print microreactors, to evaluate their efficiency, and integrate an FTIR probe into the system for realtime monitoring of the chemical reaction. The synthesis of biodiesel via transesterification was successfully performed in this study. The chemical stability of PET-G was examined by swelling tests in sunflower oil, methanol, a methanol-KOH mixture, and biodiesel. The highest stability was observed in sunflower oil, while samples immersed in the methanol-KOH mixture completely dissolved after only 15 minutes at 50 and 60 °C. The biodiesel synthesis was conducted in batch mode and in four different microreactors: a straight tubular one and three tubular with 4, 8, and 12 elbows. The conversion was monitored using an integrated FTIR probe by recording spectra every 5 minutes. A calibration curve was created based on the characteristic band at 1099 cm⁻¹, which enabled quantitative determination of conversion. The results showed that the microreactors with 0, 8, and 12 elbows achieved similar conversion values, whereas the reactor with 4 elbows exhibited low conversion and therefore showed the lowest efficiency. FTIR analysis was performed using the FTIR probe and two spectrophotometers (PerkinElmer and Shimadzu). Spectral comparison confirmed that all devices reliably detected the characteristic bands of reactants and products, although the probe showed slightly lower band intensity and a lower signal-to-noise ratio. The FTIR probe was successfully integrated and allowed continuous, real-time monitoring of the reaction
Synthesis and characterization of mesoporous zinc oxide doped with copper and nickel
No full textCinkov oksid (ZnO) je materijal poznat po izvrsnim fotokatalitičkim svojstvima, netoksičnosti i ekološkoj prihvatljivosti, zbog čega se intenzivno istražuje kao potencijalni fotokatalizator za primjenu u pročišćavanju otpadnih voda. Glavni nedostatak cinkovog oksida kao fotokatalizatora je njegova ograničena apsorpcija svjetlosti u vidljivom spektralnom području, što je posljedica njegove široke zabranjene zone. Kako bi se poboljšala optička i fotokatalitička svojstva, uvode se ioni prijelaznih metala poput bakra i nikla u kristalnu rešetku ZnO, koji formiraju nove energetske razine i poboljšavaju prijenos naboja. U ovom radu sintetizirani su i karakterizirani uzorci čistog cinkovog oksida (ZnO), cinkovog oksida dopiranog bakrom (Cu/ZnO), niklom (Ni/ZnO) te istovremeno bakrom i niklom (Cu·Ni/ZnO). Sinteza je provedena metodom mekog predloška koja se temelji na upotrebi surfaktanata ili polimera, koji služe kao predložak na kojem se precipitira cinkov oksid, a nakon termičke obrade dobiva se mezoporozni materijal. Dobiveni uzorci su karakterizirani UV-Vis difuznom refleksijskom spektroskopijom (UV-Vis DRS) kako bi se odredila energija zabranjene zone uzoraka. Infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR) je ispitana uspješnost uklanjanja polimernog predloška. Metodom rendgenske difrakcijske analize (XRD) određena je kristalna struktura te parametri jedinične ćelije. Analizom pretražnim elektronskim mikroskopom (SEM) i energijski razlučujućom rendgenskom spektroskopijom (EDS), proučavana je morfologija uzoraka i raspored elemenata na površini uzorka. Rezultati navedenih analiza potvrđuju da dopiranje ZnO ionima bakra i nikla dovodi do smanjenja energije zabranjene zone, što omogućava apsorpciju svjetla u vidljivom spektralnom području. XRD i SEM analizom kod dopiranih uzoraka potvrđena je prisutnost sekundarnih faza, ali ne dolazi do značajnog narušavanja osnovne kristalne strukture. Fotokatalitička svojstva uzoraka ispitana su fotokatalitičkom razgradnjom otopine bojila rodamina B (c0 = 10 mg/L) pod UV zračenjem. Rezultati fotokatalitičke razgradnje pokazuju zadovoljavajuću fotokatalitičku aktivnost svih pripremljenih uzoraka, među kojima se ističe uzorak Cu·Ni/ZnO kao najučinkovitiji fotokatalizator koji razgrađuje 99,2 % rodamina B unutar 10 minuta.Zinc oxide (ZnO) is a material known for its exceptional photocatalytic properties, non-toxicity and environmental friendliness, making it the subject of intensive research as a potential photocatalyst for applications in wastewater treatment. The main limitation of ZnO as a photocatalyst lies in its restricted ability to absorb light in the visible spectrum due to its wide band gap. To improve the optical and photocatalytic properties, transition metal ions such copper and nickel ions are introduced in the crystal structure of ZnO, because they can form new energy levels within the band gap and enhance charge transfer. In this work, pure ZnO, copper-doped ZnO (Cu/ZnO), nickel-doped ZnO (Ni/ZnO), and ZnO co-doped with copper and nickel (Cu·Ni/ZnO) were synthesized and characterized. The synthesis was conducted using a soft-template method based on the use of surfactants or polymers as templates, on which zinc oxide precipitates and after thermal treatment, a mesoporous material is obtained. The prepared samples were characterized using UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) to determine the band gap energies, while Fourier transform infrared spectroscopy (FTIR) was used to verify the removal of the polymer template. X-ray diffraction (XRD) was used to determine the crystal structure and unit cell parameters. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to examine the morphology and elemental distribution on the sample surface. The obtained results confirmed that doping ZnO with Cu and Ni ions reduces the band gap energy, enabling absorption in the visible light spectrum. XRD and SEM analyses indicated the presence of secondary phases in doped samples, although the basic hexagonal ZnO structure remains mostly intact. The photocatalytic properties were evaluated through the degradation of rhodamine B dye solution (c₀ = 10 mg/L) under UV light. The photocatalytic degradation results demonstrated satisfactory performance for all prepared samples, with the Cu·Ni/ZnO sample standing out as the most efficient photocatalyst, degrading 99.2% of rhodamine B within 10 minutes
Uses and health hazards of food coloring
No full textBojila za hranu su aditivi koji se dodaju kako bi se prehrambenim proizvodima zadržao ili promijenio izgled u svrhu privlačnosti potrošačima. Na tržištu su većinom proizvodi koji sadrže umjetna bojila za hranu, zbog raznih prednosti koje donose kao što su cijena, stabilnost te intenzitet obojenja koji daju hrani. Umjetna bojila mogu imati štetan učinak na zdravlje ljudi, naročito djece, zbog svojih komponenata koje u velikim količinama mogu dovesti do ozbiljnih posljedica. Zahvaljujući regulatornim tijelima, korištenje umjetnih bojila je sve ograničenije, a raširenost prirodnih bojila postaje sve poželjnija. Prijelaz prema zdravijim, prirodnim varijantama bojila postao je globalni pokret koji se proširio unatoč brojnim ograničavajućim čimbenicima. Osim čimbenika koji sintetička bojila čine povoljnima, uključuju povećanje proizvodnih procesa prirodnih bojila te manjak prirodnih sirovina. U radu su provedena istraživanja različitih vrsta bojila za hranu. Određena je količina suhe tvari pojedinog bojila te su na suhim uzorcima bojila provedene strukturna analiza, primjenom FTIR-ATR spektroskopije te su određena toplinska svojstva bojila primjenom razlikovne pretražne kalorimetrije (DSC) i termogravimetrijske analize (TGA).Food colorants are additives incorporated into food products to alter their appearance to enhance consumer appeal. The majority of products available on the food marker contain synthetic food colorants, adding various advantages such as lower cost, higher stability, and the intense coloration of the product. Synthetic colorants may have harmful effects on human health, particularly in children, due to specific components that, in high concentration, can cause serious adverse effects. Thanks to regulatory authorities, the use of synthetic colorants is increasingly restricted and the prevalence of natural alternatives has gotten considerable interest. The transition toward healthier, natural variants has become a global movement, which has spread despite numerous limiting factors which include, aside from the factors that make synthetic colorants advantageous, scaling up the production processes of natural colorants and the limited availability of raw materials. Different types of food colours were examined in the study. The amount of dry matter was determined for each colourant. Structural analysis were carried out on dry colourant samples using FTIR-ATR spectroscopy, and the thermal properties of the colourants were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)
Production and application of sophorolipids
No full textDanas se u industriji i proizvodnji sve više primjenjuje zelena kemija. Time se izbjegava upotreba kemijskih proizvoda i toksičnih otapala, te je veći naglasak na zaštitu okoliša i održivi razvoj. Biokataliza se može smatrati "zelenom kemijom" stoga se sve više primjenjuju biokatalitički procesi u industriji. U ovom radu, osim same biokatalize, opisani su i enzimi, njihova klasifikacija te primjena. U skladu sa zelenom kemijom predstavljeni su i soforolipidi, kao poznati biosurfaktanati koji se koriste zbog svoje minimalne ekotoksičnosti, visoke biorazgradivosti te dobre biokompatibilnosti. Soforolipidi pronalaze primjenu u raznim područjima industrije (farmaceutska, kemijska, prehrambena, kozmetička, poljoprivredna), u medici u liječenju raka, kao imunomodulatori i antivirusi, te u nanotehnologiji. U radu su predstavljene njihove prednosti i nedostaci, struktura te mogućnosti modifikacija. Također se opisuje i primjer dobivanja soforolipida procesom izolacije i pročišćivanja.Today, "green chemistry" has been increasingly applied in industry and manufacturing, which avoids chemical products and toxic solvents, emphasizing environmental protection and sustainable development. Biocatalysis is considered "green chemistry"; therefore, biocatalytic processes are increasingly applied in industry. In addition to biocatalysis, enzymes are also discussed in this work, along with their classification and where they are mainly used. Under the process of "green chemistry", sophorolipids (also known as biosurfactants), used due to their minimal ecotoxicity, high biodegradability, and good biocompatibility, are also described. Sophorolipids are utilized in various ways: industry (pharmaceutical, chemical, food, cosmetic, agricultural), cancer treatments (acting as immunomodulators and antivirals), and nanotechnology. This work explains advantages and disadvantages, structure, and modification of sophorolipids. Also, the method of obtaining sophorolipids by undergoing the process of isolation and purification is described
Immobilization of halohydrin dehalogenase and application in the rotating bed reactor
No full textBiokataliza predstavlja upotrebu enzima za ubrzavanje kemijske reakcije iz koje sami enzimi izlaze nepromijenjeni. Enzimi su izrazito važne molekule u farmaceutskoj industriji, jer posjeduju značajnu regio-, kemo- i stereoselektivnost te omogućuju dobivanje čistih aktivnih farmaceutskih komponenti. Jedni od zanimljivijih enzima u području dobivanja ovih komponenti su halogenhidrin-dehalogenaze (HHDH). Ovi enzimi pripadaju skupini liaza i izrazito su važni industrijski enzimi koji se mogu primijeniti kod sinteze optički aktivnih epoksida, β-supstituiranih alkohola, kao i kiralnih tercijarnih alkohola. U današnje vrijeme ovi se enzimi uglavnom dobivaju prekomjernom ekspresijom u rekombinatnim stanicama Escherichia coli. Kako bi se poboljšala svojstva enzima, oni se podvrgavaju procesu imobilizacije na nosiocu ili bez nosioca umrežavanjem. Imobilizirani enzimi pokazali su se izrazito učinkoviti za komercijalnu upotrebu zbog ekonomičnosti procesa u kojem se koriste, veće stabilnosti i mogućnosti recikliranja enzima. Jedna od dostupnih metoda uključuje imobilizaciju enzima ili cijele stanice u polimernu maticu kalcijeva alginata, koja posjeduje različite prednosti poput blagih uvjeta polimeriziranja, netoksičnosti, biokompatibilnosti, ekonomičnosti i otpornosti na kontaminaciju različitim mikroorganizmima. Organski fluorirani spojevi izrazito su važne građevne molekule u farmaceutskoj, agronomskoj i industriji funkcijskih materijala. Oni pokazuju različita jedinstvena fizikalna, kemijska i biološka svojstva u odnosu na nefluorirane spojeve, međutim njihova dostupnost proizlazi gotovo u potpunosti iz umjetne sinteze. Zbog ove potrebe, kao i zbog potrebe za zelenim pristupom ovom problemu, u njihovo dobivanje uključeni su enzimi, čija upotreba dovodi do uštede energije, pridonosi zaštiti okoliša, sigurnosti, visokoj selektivnosti procesa itd. U ovom radu uspješno je provedena imobilizacija rekombinantnih stanica E. coli koje sadrže HheC-ISM4 enzim na alginatnim zrnima, te je s istima potom uspješno provedena reakcija sinteze
(S)-2-(4-fluorfenil)-3-hidroksipropanonitrila u reaktoru s rotirajućim slojem. Pritom je dobiveno izrazito visoko iskorištenje na produktu, 98,87 %, visoka konverzija supstrata, 75,61 %, kao i visoka optička čistoća koja je bila izražena preko enantiomernog suviška supstrata i iznosila je 87,61 %.Biocatalysis represents the application of enzymes to accelerate a chemical reaction from which the enzymes themselves exit unchanged. Enzymes are extremely important biological molecules in the pharmaceutical industry, because they possess significant regio-, chemo- and stereoselectivity and allow obtaining pure active pharmaceutical components. Halohydrin-dehalogenase (HHDH) is one of the more interesting enzymes in the field of obtaining these components. These enzymes, which belong to the group of lyases, are extremely important industrial enzymes that can be used in the synthesis of optically active epoxides, β-substituted alcohols, as well as chiral tertiary alcohols, and nowadays are mostly obtained by overexpression in recombinant Escherichia coli cells. In order to improve properties of the enzymes, enzymes are subjected to the process of immobilization on a carrier or without a carrier by cross-linking. Immobilized enzymes have proven to be extremely effective for commercial use due to lower costs of the process, greater stability and the possibility of recycling the enzyme. One of the available immobilization methods is the immobilization of enzymes or whole cells in a polymer matrix of calcium alginate, which has various advantages such as mild polymerization conditions, non-toxicity, biocompatibility, economical advantages and resistance to contamination by various microorganisms. Organic fluorinated compounds are extremely important building molecules in the pharmaceutical, agronomic and functional materials industry. They show different unique physical, chemical and biological properties compared to non-fluorinated compounds, however their availability results almost entirely from artificial synthesis. Due to this, as well as due to the need for development of green industry, enzymes are included in their production, the use of which leads to energy savings, contributes to environmental protection, safety, high process selectivity, etc. In this work, the process of immobilization of recombinant Escherichia coli cells containing the HheC-ISM4 enzyme on alginate beads was successfully carried out, with which the synthesis reaction of (S)-2-(4-fluorophenyl)-3-hydroxypropanonitrile was successfully carried out in a rotating bed reactor. High product yield was obtained, 98.87%, as well as high conversion of the substrate, 75.61%, and high optical purity expressed through the enantiomeric residue of the substrate, 87.61%