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New heterostilbenes as potential cholinesterase inhibitors or reactivators – synthesis and photochemistry
No full textU ovoj disertaciji, predložena je sinteza novih stilbenskih derivata koje u svojim strukturama sadrže heterocikličke jezgre furana, tiofena, triazola, tiazola i piranona. Sinteza je uspješno provedena koristeći Wittigovu reakciju, McMurryjevu reakciju i Buchwald-Hartwigovu reakciju aminiranja. Na sintetiziranim konjugiranim molekulama provedena su fotokemijska osvjetljavanja u svrhu dobivanja novih elektrociklizacijskih fotoprodukata. Na novim derivatima provedena su ispitivanja njihove biološke aktivnosti kao potencijalnih inhibitora enzima kolinesteraza s protuupalnim i antioksidacijskim djelovanjem ili kao reaktivatora kolinesteraza. Kao modelne molekule služile su poznati stilbenski derivati s izraženom biološkom aktivnošću kao što su rezveratrol, pterostilben i drugi. Heterostilbenski derivati sadrže i heterocikličke jezgre koje su ključne u metabolizmu živih stanica, a od iznimne su važnosti i za razvoj agenasa protiv neurodegenerativnih bolesti, kod kojih vodeću ulogu igraju upravo enzimi kolinesteraze. Kako se različiti heterostilbenski derivati već primjenjuju i u izradi nelinearnih optičkih materijala (NLO), detaljno su se uz fotokemijsku reaktivnost i nastajanje fotociklizacijskih produkata ispitivalo i fotofizičko ponašanje novih heterostilbena. Sinteza se provodila konvencionalnim pristupom, ali i suvremenim sintetskim pristupom, primjenom protočne kemije i protočne fotokemije, u cilju povećanja produktivnosti i ekonomičnosti procesa. Na temelju računalnih metoda ispitalo se potencijalno vezivanje novih struktura u aktivna mjesta enzima kolinesteraza, ali i elektronska struktura molekula. U velikom broju novih struktura istaknuo se određeni broj molekula koje su pokazale jako dobru inhibicijsku aktivnost prema enizimima kolinesterazama, ali i antioksidacijsku i protuupalnu aktivnost. Heterostilbenski derivati s najboljim preliminarnim rezultatima daju smjernice za daljnji tijek istraživanja u pronalaženju novih inhibitora ili reaktivatora enzima kolinesteraza s dodatnim antioksidacijskim i protuupalnim učinkom ili pogodnim fotofizičkim karakteristikama. Biološka ispitivanja su provedena u suradnji sa Sveučilištem u Mostaru i tvrtkom Selvita, a računalna ispitivanja i fotofizika, te spektroskopska mjerenja provedena su u suradnji s Institutom Ruđer Bošković. Ispitivanja na kompleksiranju novih spojeva s biometalima, te tumačenja fotokatalitičkih oksigenacija provedena su u suradnji sa Sveučilištem Pannonia u Veszprému. Biološka ispitivanja reaktivacije kolinesteraza ispitivana su u suradnji s kolegama s Instituta za medicinska istraživanja i medicinu rada. Računalna ispitivanja fotokemije i fotofizike pobuđenih molekula u korelaciji s eksperimentalnim LFP rezultatima provedena su u suradnji sa Sveučilištem u Yaleu. Analize spojeva i sinteza spojeva u protočnim reaktorima provedene su u suradnji s kolegama s Fakulteta kemijskog inženjerstva i tehnologije Sveučilišta u Zagrebu i iz tvrtke Pliva.In this dissertation, the synthesis of new stilbene derivatives containing in their structures het-erocyclic nuclei of furan, thiophene, triazole, thiazole and pyranone was designed, and success-fully carried out using the Wittig reaction, the McMurry reaction and the Buchwald-Hartwig amination reaction. Photochemical illumination was performed on the synthesized conjugated derivatives in order to obtain new electrocyclization photoproducts. New derivatives were tested for their biological activity as potential cholinesterase enzyme inhibitors with anti-in-flammatory and antioxidant activity or as cholinesterase reactivators. Known stilbene deriva-tive with pronounced biological activity such as resveratrol, pterostilbene and others served as model compounds. Heterostilbene molecules contain heterocyclic nuclei that are crucial in the metabolism of living cells, and are of exceptional importance for the development of agents against neurodegenerative diseases, in which enzymes cholinesterases play a leading role. As different heterostilbene derivatives are already used in the production of nonlinear optical ma-terials (NLO), photochemical reactivity and the formation of photocyclization products were also investigated in detail, as well as the photophysical behavior of the new heterostilbenes. The synthesis was carried out with a conventional approach, but also with a modern synthetic approach, using flow-chemistry and flow-photochemistry, in order to increase the productivity and economy of the process. On the basis of computer methods, the potential binding of new structures to the active sites of enzyme cholinesterases, as well as the electronic structure of the molecules, were examined. Among the large number of new structures, a certain number of molecules stood out with very good inhibitory activity towards enzyme cholinesterases, but also antioxidant and anti-inflammatory activity. Heterostilbene derivatives with the best pre-liminary results provide guidelines for further research in finding new enzyme cholinesterase inhibitors or reactivators with additional antioxidant and anti-inflammatory effects or suitable photophysical characteristics. Biological tests were carried out in cooperation with the University of Mostar and the company Selvita, while computational study, photophysics and spectroscopic measurements were carried out in cooperation with the Ruđer Bošković Institute. Tests on the complexation of compounds with biometals, and interpretations of the photocatalytic oxygenation were carried out in coop-eration with the Pannonia University in Veszprém. Biological tests of cholinesterase reactiva-tion were investigated in collaboration with colleagues from the Institute for Medical Research and Occupational Medicine. Computational study on the photochemistry and photophysics of excited molecules in correlation with experimental results were carried out in cooperation with Yale University. Analyzes of compounds and synthesis of compounds using flow-reactors were carried out in collaboration with colleagues from the Faculty of Chemical Engineering and Technology at University of Zagreb and from the Pliva company
Preparation of conductive and stretchable PEDOT-SEBS films
No full textElektrovodljive polimere karakteriziraju jedinstvena optička i električna svojstva, slična nekim polumetalima i metalima, čineći ih široko primjenjivim organskim materijalima. Mehanička fleksibilnost, prilagodljiva vodljivost, laka obradivost, biokompatibilnost samo su neke od karakteristika koje omogućuje njihovu primjenu u raznim područjima tehnologije, od uređaja za pohranu energije do fleksibilne nosive elektronike. Visoko vodljiv i kemijski stabilan PEDOT jedan je od najvažnijih predstavnika elektrovodljivih polimera koji stvarajući kopolimere i polimerne mješavine proširuje svoju primjenu u nosivoj elektronici. U ovome radu, izrađuju se istezljivi i vodljivi PEDOT-SEBS filmovi sintezom kopolimera koristeći EDOT monomer i ThBr monomer u omjeru 1:1 i termoplastični elastomer SEBS. Uspješnost sinteze kopolimera potvrđena je infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR), a toplinska stabilnost ispitana je termogravimetrijskom analizom (TGA) i diferencijalno pretražnom kalorimetrijom (DSC). Na staklenim supstratima izrađeni su filmovi čija je početna provodnost te provodnost prilikom cikličkog naprezanja ispitana metodom sonde s četiri točke (4PP), a morfologija je određena pretražnim elektronskim mikroskopom (SEM). Ispitana je stabilnost u otopini NaCl-a i mehanička svojstva filmova. Rezultati karakterizacija potvrdili su uspješnu sintezu i izradu polimernog filma PEDOT-Br:S-SEBS kopolimera koji je pokazao zadovoljavajuća mehanička svojstva i stabilnost. Potvrđena električna provodnost omogućava daljnjom optimizacijom uporabu polimernog filma u nosivoj elektronici.Electrically conductive polymers exhibit unique optical and electrical properties similar to those of some semimetals and metals, making them widely applicable organic materials. Mechanical flexibility, adaptable conductivity, ease of processing and biocompatibility are just some of the characteristics that enable their use in various technology fields, from energy storage devices to flexible wearable electronics. Highly conductive and chemically stable PEDOT is one of the most important representatives of electrically conductive polymers, which expands its application in wearable electronics by forming copolymers and polymer blends In this study, stretchable and conductive PEDOT-SEBS films are prepared by synthesising a copolymer of EDOT monomer and ThBr monomer in a 1:1 ratio, together with SEBS thermoplastic elastomer. The success of the copolymer synthesis was confirmed by Fourier transform infrared spectroscopy (FTIR) and the thermal stability was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The films were prepared on glass substrates, and their initial conductivity and conductivity under cyclic straining were investigated by a four-point probe (4PP) method, while the morphology was determined by scanning electron microscopy (SEM). The stability in NaCl solution and mechanical properties of the films were also assessed. The characterization results confirmed the successful synthesis and preparation of the PEDOT-Br:S-SEBS copolymer film, which exhibited satisfactory mechanical properties and stability. The confirmed electrical conductivity enables further optimization for the use of the polymer film in wearable electronics
Application of polymers with pharmaceutical molecular imprints in the preparation of water samples for chromatographic analysis
No full textNajčešće korišten postupak uklanjanja interferencija i izolacije analita je ekstrakcija čvrstom fazom. U odnosu na konvencionalne sorbense koji se koriste za pripremu uzorka, najvažnja značajka polimera s otiskom molekule je visoka selektivnost prema ciljanim analitima. Osim za ekstrakciju farmaceutika, polimeri s otiskom molekule primjenjuju se za ekstrakciju teških metala, industrijskih boja, patogenih organizama, raznih pesticida itd. Priprema uzorka primjenom polimera s otiskom molekule ima posebnu važnost prilikom analize mikroonečišćivala u uzorcima iz okoliša. Kao vodeće prednosti nad ostalim sorbensima, uz visoku selektivnost, mogu se izdvojiti visoka stabilnost te jednostavna i jeftina priprema. Ekstrakcija primjenom polimera s otiskom molekule može se provoditi u on-line ili off-line načinu rada. Za njenu učinkovitu provedbu, nužno je kontrolirati čimbenike koji mogu smanjiti učinkovitost ekstrakcije polimerom s otiskom molekule poput: utjecaja pH-vrijednosti, količine sorbensa, volumen uzorka, izbor otapala za eluiranje, brzine protoka uzorka te ionske jakosti.Solid phase extraction is the most commonly used procedure for the removal of interferences and isolation of analytes. Compared to conventional sorbents used for sample preparation, the most important feature of molecularly imprinted polymers is their high selectivity towards target analytes. In addition to the extraction of pharmaceuticals, molecularly imprinted polymers are used for the extraction of heavy metals, industrial dyes, pathogenic organisms, various pesticides, etc. Sample preparation using molecularly imprinted polymers is of particular importance when analyzing micropollutants in environmental samples. The leading advantages, in addition to gih selectivity, are high stability and simple and inexpensive preparation. Extraction using molecularly imprinted polymers can be performed in on-line or off-line mode. For its effective implementation, it is necessary to control factors that can reduce the efficiency of the extraction by molecularčy imprinted polymer, such as: the influence of the pH value, the amount of sorbent, sample volume, choice of washing solvent and elution solvent, sample flow rate and ionic strength
Application of TiO2 photocatalyst for the removal of cytostatic drugs from water
No full textZaštita i očuvanje vodenih resursa izazov je na globalnoj razini s kojim se današnjica susreće. Uz konvencionalne postupke obrade voda razvijaju se i napredni oksidacijski procesi koji su se zbog svog neselektivnog ponašanja pokazali učinkovitijim za uklanjanje malih organskih molekula poput farmaceutika čija prisutnost u okolišu više ne iznenađuje. Među raznim vrstama lijekova, svoj put u okolišu, ponajviše kroz otpadne vode pronašli su i lijekovi protiv raka (citostatici) koji zahtijevaju pažnju zbog povećane potrošnje i bioloških učinaka na organizme, već pri niskim koncentracijama. U ovome radu izabrana su dva citostatika, imatinib i krizotinib čija se mogućnost uklanjanja iz vode ispitala kroz sorpcijsku i fotokatalitičku aktivnost primjenom TiO2 fotokatalizatora. Prema mehanizmu fotokatalitičkog procesa, ispitivana komponenta podlijegat će razgradnji ako se prethodno sorbira na katalizator pa se sukladno tome, u prvom nizu eksperimenata proučavao sorpcijski afinitet citostatika prema različitim oblicima TiO2 fotokatalizatora, koristeći nekoliko modela sorpcijskih izotermi. Općenito se, na temelju određene količine sorbirane tvari, ispitala i primjenjivost sorpcije kao jednostavnije i jeftinije metode za uklanjanje imatiniba i krizotiniba iz vode ili kao preteča neke druge oksidacijske metode. Priroda procesa sorpcije, provedenog pri tri različite temperature opisana je promjenom početne koncentracije analita, pH-vrijednosti i ionske jakosti otopine te promjenom mase sorbensa. Visoke vrijednosti regresijskog koeficijenta, R2 upućuju na prikladnost linearne, Freundlichove i Langmuirove izoterme za opisivanje sorpcije citostatika na suspendirani i imobilizirani oblik TiO2. Oba analita pokazuju rastući trend koeficijenta sorpcije s porastom vrijednosti pH u rasponu od 5 do 9 s naglaskom na veću mobilnost imatiniba u slučaju imobiliziranog TiO2. Pozitivna korelacija određena je i između temperature, mase sorbensa i koeficijenta sorpcije, dok je porastom ionske jakosti otopine krizotinib pokazao suprotan trend. Termodinamika sorpcije opisana je kao spontan proces fizikalne prirode koji slijedi kinetiku pseudo-drugog reda. Što se tiče eksperimenata fotokatalize, prvo su se odredile vrijednosti početne koncentracije analita i pH otopine pri kojoj citostatici postižu optimalnu razgradnju, primjenom modeliranja odzivnih površina (RSM). Pri dobivenim uvjetima (pH 5 i 5 mg/L) ispitan je mehanizam fotokatalitičke reakcije, određivanjem radikalskih vrsta odgovornih za razgradnju. Vodeću ulogu u razgradnji imatiniba i krizotiniba pokazali su hidroksilni radikali i singletni kisik. U sljedećim eksperimentima pokazana je važnost provođenja fotokatalize u prisustvu raznih anorganskih i organskih tvari kao sastavnica matice vode koji su većinski usporili razgradnju. Kao i svaki drugi proces razgradnje, fotokataliza imatiniba i krizotiniba također je bila popraćena stvaranjem nusprodukata čije su strukture i putevi razgradnje predloženi korištenjem spektrometrije masa visokog razlučivanja. Potencijalna opasnost razgradnih produkata procijenjena je testom akutne toksičnosti prema morskoj bakteriji Vibrio fischeri, pri čemu je postignuta značajna inhibicija luminiscencije tijekom fotokatalitičke razgradnje krizotiniba u razdoblju od 90. do 180. minute. Kao fotokatalizator koristio se TiO2 imobiliziran na staklene mrežice koji je olakšao samu provedbu eksperimenata pritom misleći na filtriranje uzoraka.The protection and conservation of water resource is a global challenge facing humanity today. In addition to conventional water treatment, advanced oxidation processes are also being developed to non-selectively and efficiently remove small organic molecules such as pharmaceuticals, whose presence in the environment is no longer surprising. Among the different classes of pharmaceuticals, anti-cancer drugs (cytostatics) have also found their way into the environment, mostly through wastewater, which requires attention due to their increased consumption and biological effects, even at low concentrations. In this work, two cytostatics, imatinib and crizotinib, were selected and their ability to be removed from water was tested by sorption and photocatalytic activity with TiO2 photocatalysts. The prerequisite step of the photocatalytic process is the sorption of the tested component on the catalyst, so in the first series of experiments the sorption affinity of cytostatics to different forms of TiO2 was investigated. In addition, based on the studied sorption affinity, the applicability of sorption as a simpler and less expensive method for the removal of imatinib and crizotinib or as a complementary method to some oxidation processes was tested. The nature of the sorption process was described by changing the initial concentration of the analyte, the pH value and the ionic strength of the solution, and by performing experiments at three different ambient temperatures and different sorbent dosages. The suitability of the linear, Freundlich, and Langmuir isotherm models for describing the sorption of cytostatics on the suspended and immobilized forms of TiO2 was indicated by high values of the regression coefficient, R2. Both analytes showed an increasing trend in the sorption coefficient with increasing pH values in the range of 5 to 9, highlighting the greater mobility of imatinib in the case of immobilized TiO2. A positive correlation was also observed between temperature, sorbent mass and sorption coefficient, while the increase in ionic strength of crizotinib solution showed the opposite trend. The thermodynamics of sorption is described as a spontaneous process of physical nature that follows pseudo-second-order kinetics. In the first step of the photocatalytic experiments, the initial concentration of the analyte and the pH of the solution, at which the cytostatic reaches the optimal degradation, were tested using response surface modelling (RSM). Under the conditions obtained (pH 5 and 5 mg/L), the mechanism of the photocatalytic reaction was studied by determining the main radical species involved in the degradation. Hydroxy radicals and singlet oxygen played the main role in the degradation of imatinib and crizotinib. The importance of performing photocatalysis in the presence of various organic and inorganic substances as common components of the water matrix was also demonstrated, since most of them slow down the degradation. Like any other degradation process, photocatalysis of imatinib and crizotinib was accompanied by the formation of by-products, whose structures and degradation pathways were suggested by high-resolution mass spectrometry. The hazard potential of the degradation products was assessed by an acute toxicity assay with the marine bacterium Vibrio fischeri, with significant inhibition of luminescence during photocatalytic degradation of crizotinib over period of 90 to 180 minutes. TiO2 immobilized on glass meshes was used as the photocatalyst, which facilitated the performance of the experiments by avoiding filtering of the samples
Development and validation of a chromatographic method for the determination of selected carboxylic acids
No full textHalooctene kiseline su dezinfekcijski nusprodukti koji nastaju kada se sirova voda dezinficira klorom. Djelovanje i štetnost halooctenih kiselina za ljudsko zdravlje još uvijek nije sasvim istraženo i stoga se neprestano razvijaju i optimiraju analitičke metode kojima se nadzire njihova koncentracija u obrađenim vodama. Kroz ovaj rad analizirane su kloroctena, trikloroctena i bromoctena kiselina na način da su derivatizacijom prevedene u estere, nakon čega su snimljeni NMR i UV-Vis spektri derivata, te su potom analizirane kromatografskom HPLC-DAD metodom. Dodatno je provedena i GC-MS analiza trikloroctene i bromoctene kiseline. NMR analizom potvrđena je uspješna derivatizacija trikloroctene i bromoctene kiseline te djelomična derivatizacija kloroctene kiseline. UV-Vis analizom ustanovljeni su apsorpcijski maksimumi dobivenih derivata. Uz kvalitativnu kromatografsku analizu, razvijena je i validirana HPLC-DAD metoda za kvantitativno određivanje trikloroctene i bromoctene kiseline. Sve ispitane izvedbene karakteristike validacije zadovoljene su obzirom na postavljene kriterije. GC-MS analizom uspješno su detektirane trikloroctena i bromoctena kiselina.Haloacetic acids form as disinfection byproducts when raw water is disinfected with chlorine. Since the harmful and adverse effects of haloacetic acids on human health have not yet been fully investigated, analytical methods are constantly being developed and optimized to monitor their concentration levels in water. In this paper, chloroacetic, trichloroacetic and bromoacetic acids were analyzed in such a way that they were converted into esters by derivatization, after which the NMR and UV-Vis spectra of the derivatives were obtained, and then they were analyzed using the chromatographic HPLC-DAD method. Additionally, GC-MS analysis of trichloroacetic and bromoacetic acids was carried out. NMR analysis confirmed the successful derivatization of trichloroacetic and bromoacetic acids as well as the partial derivatization of chloroacetic acid. UV-Vis analysis was used to determine the absorption maxima of the derivatives. Along with the qualitative chromatographic analysis, a new method for quantitative analysis of trichloroacetic and bromoacetic acids was developed and validated. All validation characteristics that were examined have met the set criteria. Trichloroacetic and bromoacetic acid were successfully detected with GC-MS analysis
The influence of electrolyte on the results of electrochemical measurements
No full textU ovome radu istraživan je utjecaj izbora elektrolita na rezultate dobivene elektrokemijskim ispitivanjima, preciznije elektrokemijskom impedancijskom spektroskopijom, te polarizacijskim mjerenjima koja se baziraju na istosmjernoj struji. Koristile su se tri vrste elektrolita: jedan tekući – umjetna kiša, te dva hidrogel elektrolita – jedan na bazi agara i drugi na bazi poli(vinilalkohola). Ispitivanja s tekućim elektrolitom provođena su u klasičnoj elektrokemijskoj ćeliji s troelektrodnim sustavom – radnom elektrodom od ispitivanog materijala, referentnom zasićenom kalomel elektrodom (ZKE) i grafitnom protuelektrodom. Ispitivanja s hidrogel elektrolitima provođena su u elektrokemijskim ćelijama, gdje su kao referentna elektroda i protuelektroda korištene žice od nehrđajućeg čelika AISI 316L. Ispitivano je pet vrsta radnih elektroda – bakar, bronca, ugljični čelik, nitratna (zelena) patina, te sulfidna (crna) patina. Utvrđeno je da su rezultati dobiveni korištenjem agar i poli(vinil-alkohol) hidrogelova međusobno sličniji nego oni dobiveni korištenjem tekućeg elektrolita, iako sva tri elektrolita daju približne rezultate. Također se zaključuje da je otpor elektrolita uglavnom najvećeg iznosa prilikom korištenja tekućeg elektrolita, a najveći otpori prijenosu naboja i otpori oksida uglavnom se javljaju prilikom korištenja agar elektrolita. Najveći polarizacijski otpori dobivaju se također korištenjem agar elektrolita, a najvećih su iznosa na patinama kao radnim elektrodama. Najveći polarizacijski otpori, u sva tri elektrolita, javljaju se na nitratnoj (zelenoj) patini, a najniži na ugljičnom čeliku.This paper investigated the impact of electrolyte on the results obtained by electrochemical tests, more precisely by electrochemical impedance spectroscopy and polarization measurements that are based on direct current. Three types of electrolytes were used: one liquid – artificial rain, and two hydrogel electrolytes – one based on agar and the other based on poly(vinyl alcohol). Tests with liquid electrolyte were performed in a classical electrochemical cell with a three-electrode system – working electrode made of test material, a reference saturated calomel electrode (SCE) and a graphite counter electrode. Tests with hydrogel electrolytes were performed in electrochemical cells, with the reference electrode and counter-electrode AISI 316L stainless steel wires. Five types of working electrodes – copper, bronze, carbon steel, nitrate ( green ) patina, and sulfide ( black) patina were tested. The results obtained using agar and poly(vinylalcohol) hydrogels were found to be more similar than those obtained using liquid electrolytes, although all three electrolytes give comparable results. It is also concluded that electrolyte resistance is generally the highest when using a liquid electrolyte, while the greatest resistances to charge transfer and oxide resistance generally occur when using agar electrolytes. The greatest polarization resistances are also obtained by using agar electrolytes, and the largest are observed on patinas as working electrodes. The highest polarization resistances, in all three electrolytes, occur on nitrate (green) patina, and the lowest on carbon steel
Adsorption of organic contaminants on an adsorbent prepared from hazelnut shells
No full textAdsorpcija je proces nagomilavanja čestica iz tekuće ili plinske faze na površinu krute faze. Kao separacijski proces ima veliku važnost u industriji te se svakodnevno proučava. Koristi se za pročišćavanje plinova (uklanjanje SO2, CO2, NOx, itd.), a u pročišćavanju tekućina najvažniju primjenu ima za uklanjanje organskih tvari iz vode i za pročišćavanje vode za piće i otpadnih voda. U ovom radu uspoređivana je adsorpcija mravlje i octene kiseline te
1,4 – dioksana na granuliranom aktivnom ugljenu (komercijalnom) i ugljenu pripremljenom od ljusaka lješnjaka s metodom 1 (aktivacija sa sumpornom kiselinom) i metodom 2 (aktivacija s klorovodičnom kiselinom). Određena je specifična aktivna površina aktivnih ugljena snimanjem adsorpcijsko-desorpcijskih izotermi dušika. Ispitivanje je provedeno šaržnom adsorpcijom. Usporedbom dobivenih Freundlich-ovih izotermi, procijenjen je afinitet adsorpcije pojedinih organskih zagađivala na različitim vrstama aktivnog ugljena. Analizom rezultata, može se zaključiti da granulirani aktivni ugljen ima veću specifičnu površinu i volumen pora od ugljena od ljusaka lješnjaka pripremljenog metodom 1, dok je srednji promjer pora isti kod obje vrste ugljena. Najveću količinu karboksilnih kiselina može adsorbirati granulirani aktivni ugljen, zatim ugljen od ljusaka lješnjaka dobiven metodom 1, a najmanju ugljen od ljusaka lješnjaka dobiven metodom 2. Granulirani aktivni ugljen može adsorbirati veću količinu 1,4 – dioksana nego ugljen pripremljen od ljusaka lješnjaka metodom 1.Adsorption is the process of the accumulation of particles from the liquid or gas phase to the surface of the solid phase. As a separation process, it is of great importance in industry and is being studied on a daily basis. It is used for gas purification (removal of SO2, CO2, NOx, etc.), and its most important application in the purification of liquids is the removal of organic compounds from water and the purification of drinking water and wastewater. In this work, the adsorption of formic acid, acetic acid, and 1,4-dioxane on granular activated carbon (commercial) and on carbon prepared from hazelnut shells by Method 1 (activation with sulfuric acid) and Method 2 (activation with hydrochloric acid) was compared. The specific active surface area of the activated carbons was determined by recording the adsorption-desorption isotherms of nitrogen. The study was carried out by batch adsorption. By comparing the obtained Freundlich isotherms, the adsorption affinity of individual organic pollutants on different types of activated carbon was estimated. From the analysis of the results, it can be concluded that granular activated carbon has a larger specific surface area and pore volume than the activated carbon prepared from hazelnut shells by Method 1, while the average pore diameter is the same for both types of activated carbon. The largest amount of carboxylic acids can be adsorbed by granular activated carbon, then by carbon prepared from hazelnut shells by Method 1, and the smallest amount can be adsorbed by carbon prepared from hazelnut shells by Method 2. Granular activated carbon can adsorb a greater amount of 1,4-dioxane than the carbon prepared from hazelnut shells by Method 2
Influence of bioactive glass on properties of composite microspheres
No full textKitozan, linearni polisaharid koji se može dobiti djelomičnom deacetilacijom prirodnog polimera hitina, odlikuje se izuzetnim fizikalno-kemijskim svojstvima poput biorazgradljivosti i biokompatibilnosti. Osim proučavanja keliranja s metalnim ionima do danas je mali broj istraživanja proveden s ciljem povezivanja kitozana s drugim komponentama. Cilj ovoga rada je priprava kompozitnih mikrosfera na temelju kitozana, Cu2+ iona i bioaktivnog stakla metodom elektroštrcanja. Pretražnim optičkim fluorescentnim i pretražnim elektronskim mikroskopom, rendgenskom analizom i infracrvenom spektroskopijom ispitan je utjecaj različitog udjela bakrovih (II) iona i bioaktivnog stakla na veličinu, oblik, morfologiju te sastav kitozanskih mikrosfera. Nađeno je da je površina mikrosfera naborana, neporozna i uglavnom sferična za sve uzorke osim za one s najmanjim ispitanim udjelom Cu2+ iona. Dodatkom bioaktivnog stakla na površini kompozitnih mikrosfera uočene su izbočine za koje je detekcija atoma SEM-EDS metodom potvrdila da su čestice biostakla. Raspodjela veličina čestica seže od 38 μm do 60 μm i ovisi o sastavu. Povećanjem udjela Cu2+ iona i povećanjem udjela bioaktivnog stakla mikrosfere imaju sve uniformniju raspodjelu i interval raspodjele veličine čestica se znatno sužava. FTIR spektri pokazuju da dodatak metalnog iona dovodi do neznatne razlike u položaju vrpci koje odgovaraju vibracijama O-H i N-H veza, iz čega se zaključuje kako na tim skupinama dolazi do povezivanja kitozana i bakra. Dodatkom bioaktivnog stakla ne uočavaju se značajnije razlike. Difrakcijska slika kitozana ne mijenja se uz Cu2+ ione, što potvrđuje stvaranje kompleksa, a pojavljuje se novi difrakcijski maksimum karakterističan za bioaktivno staklo. Primjenom metode elektroštrcanja uz kontroliranu promjenu udjela bakra i bioaktivnog stakla može se utjecati na morfologiju i raspodjelu veličine kompozitnih mikrosfera na temelju kitozana.Chitosan, a linear polysaccharide that can be obtained by partial deacetylation of the natural polymer chitin, possesses exceptional physicochemical properties, including biodegradability and biocompatibility. Apart from the study of chelation with metal ions, there is a small amount of research based on chitosan's connection to other components. The aim of this work is to prepare composite microspheres based on chitosan, Cu2+ ions and bioactive glass using an electrospraying method. The influence of different proportions of copper (II) ions and bioactive glass on the size, shape, morphology and composition of chitosan microspheres was investigated using scanning optical fluorescence and scanning electron microscopy, X-ray analysis and infrared spectroscopy. The surface of the microspheres is wrinkled, non-porous and mostly spherical for all samples except those with the smallest investigated proportion of Cu2+ ions. Upon introducing bioactive glass, noticeable protrusions are observed on the surface of the composite microspheres, which are confirmed by SEM-EDS atomic detection to be bioglass particles. The distribution of particle sizes ranges from 38 μm to 60 μm depending on the composition of each sample. With the increase of Cu2+ ion and bioglass content, the microspheres have a more uniform size distribution and the interval of particle size distribution narrows significantl. FTIR spectra show that the addition of the metal ion leads to a minor difference in the position of the bands corresponding to the O-H and N-H bond vibrations, indicating the interaction between chitosan and copper in these functional groups. Conversely, no significant differences are observed with the addition of bioactive glass. Likewise, the diffraction pattern of chitosan does not change with Cu2+ ions, which confirms the formation of a complex, while a new diffraction maximum characteristic for bioactive glass appears. The morphology and size distribution of composite chitosan-based microspheres obtained by electrospraying method can be controlled with the amount of cupric ions and bioactive glass
Synthesis, analysis of physico-chemical properties and biological activity of new heteroaromatic derivatives of resveratrol
No full textTijekom izrade završnog rada provedena je sinteza novih heteroaromatskih derivata rezveratrola kao potencijalnih antioksidansa. Spojevi 2-6 sintetizirani su Wittigovom reakcijom odgovarajućeg aldehida i fosfonijeve soli kao smjese izomera, iz kojih su kasnije tankoslojnom, kolonskom i preparativnom kolonskom kromatografijom izdvojeni čisti izomeri. Spojevi 3 i 4 uspješno su dobiveni u cis- i trans-konfiguraciji, dok je kod ostalih nastajao uglavnom samo trans-izomer. Svi su spojevi spektroskopski okarakterizirani tehnikama UV te 1H i 13C NMR. Ispitivanja biološke aktivnosti provedena su u smislu istraživanja njihove antioksidacijske aktivnosti na stabilizaciju DPPH radikala i mogućnost inhibicije acetilkolinesteraze i butirilkolinesteraze.During the preparation of the final thesis, the synthesis of new heteroaromatic derivatives of resveratrol as potential antioxidants was conducted. Compounds 2-6 were synthesized through the Wittig reaction of the corresponding aldehyde and phosphonium salt as mixtures of isomers, from which pure isomers were later separated using thin-layer, column and preparative column chromatography. Compounds 3 and 4 were successfully obtained in cis- and trans-configurations, while the others were obtained in the reaction mainly as trans-isomers. All compounds were spectroscopically characterized using UV and 1H and 13C NMR techniques. Biological activity testing was conducted to explore their antioxidant activity in stabilizing DPPH radicals and the potential inhibition of acetylcholinesterase and butyrylcholinesterase
Mathematical modeling of biocatalytic reactions
No full textKombinacijom prirodnih znanosti poput matematike i kemije omogućava se primjena metoda koje pristupaju znanosti na jedan novi, „zeleniji“ način. Društvo, kao i sama industrija nastoje težiti primjeni ekonomičnih, održivih i prirodnih tvari koje neće štetiti okolišu. Primjenom biokatalitičkih procesa to je moguće i ostvariti. U ovom radu opisani su enzimi, njihova klasifikacija, prednosti i mane kao katalizatora te njihova primjena. Također, dan je prikaz matematičkog modeliranja biokatalitičkih reakcija. Govori se o bilancnim jednadžbama i reaktorima u kojima se odvijaju biokatalitički procesi. Matematičkim modeliranjem povezuju se bilancne i kinetičke jednadžbe u kemijskim procesima. Primjena matematičkih modela olakšava odabir pogodnog reaktora za pojedinu reakciju, a također omogućava i ubrzava optimizaciju procesa.The combination of natural sciences such as mathematics and chemistry enables the application of methods that approach science in a new, "greener" way. Society, as well as the industry itself, strives to use more economical, sustainable and natural substances that will not harm the environment. Such an approach can be achieved by using biocatalytic processes. This thesis describes enzymes, their classification, advantages and disadvantages as catalysts, and their application as well as mathematical modeling of biocatalytic reactions. Mass balance equations and reactors in which the biocatalytic processes take place are described. The application of mathematical modeling enables the selection of adequate reactors for a specific reaction and also aids and speeds up optimization of the process