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Extraction of pharmaceuticals mixture from water
No full textZbog široke primjene i velike potrošnje farmaceutici su češće zastupljeni u okolišu te dospijevaju u slojeve tla, podzemne i površinske vode. Ugrožavaju živote organizama i negativno utječu na cjelokupni ekosustav. Nužno je razvijati metode za otkrivanje prisutnosti farmaceutika u okolišu kako bi se pospješila kvaliteta ljudskog života. U ovom radu je razvijena metoda za analizu dvanaest farmaceutika (amoksicilin, atenolol, prokain, ofloksacin, sulfametazin, sulfametoksazol, torasemid, karbamazepin, deksametazon, ß-estradiol, diazepam, diklofenak) s različitim fizikalnim i kemijskim svojstvima iz otpadnih voda. Kao metoda pripreme uzorka ispitivanih farmaceutika iz vode odabrana je ekstrakcija čvrstom fazom čija je učinkovitost određena tekućinskom kromatografijom visoke djelotvornosti s DAD detektorom. Najbolja iskorištenja su polučena korištenjem 100 mL izvorske vode pri pH 8, uz metanol kao otapalo za eluiranje u dva obroka od po 2 mL. Po završetku optimiranja parametara za ekstrakciju, metoda je validirana. Prethodno razvijena metoda je nakon validacije primijenjena na stvarnim uzorcima otpadnih voda iz bolnice.Due to their widespread use and high consumption, pharmaceuticals are increasingly present in the environment and enter in soil layers, groundwater and surface water. They threaten the life of organisms and negatively affect the entire ecosystem. It is necessary to develop methods for detecting the presence of pharmaceuticals in the environment to improve the quality of human life. In this study, a method was developed for the analysis of twelve pharmaceuticals (amoxicillin, atenolol, procaine ofloxacin, sulfamethazine, sulfamethoxazole, torasemide, carbamazepine, dexamethasone, β-estradiol, diazepam, diclofenac) with different physical and chemical properties from wastewater. Solid phase extraction was chosen as the method for preparing the sample of tested pharmaceuticals from water, and its efficiency was determined by high-performance liquid chromatography using a DAD detector. The best efficiency was obtained using 100 mL of spring water at pH 8, with methanol as eluent in two portions of 2 mL each. After completing the optimization of the extraction parameters, the method was validated. After validation, the previously developed method was applied to real hospital wastewater samples
Application of the Full Factorial Plan and Response Surface Methodology to determine the ecotoxic effects of xenobiotics on Daphnia magna
No full textOnečišćenje vodenog ekosustava ksenobioticima, mikroplastikom (MP) i farmaceuticima, je u sve većem porastu zbog antropogenih utjecaja, poput prekomjernog korištenja plastične ambalaže, razvoja industrije i konzumiranja lijekova, što posljedično dovodi do njihovih ispuštanja u okoliš. MP se smatra onečišćujućom tvari jer je postala globalna prijetnja zbog svoje sveprisutnosti, bioinertnosti, opasnosti za vodene organizme i utjecaja na ljudsko zdravlje. Farmaceutici poput antibiotika i antivirotika čine skupinu onečišćujućih tvari koje mogu ozbiljno ugroziti zdravlje neciljanih organizama. Onečišćenje vodenog ekosustava postalo je svjetski problem, a znanstvenici, u suradnji sa zakonodavnim tijelima, traže rješenja kako spriječiti daljnje onečišćenje okoliša. U svrhu procjene toksičnosti MP-a, antibiotika i antivirotika te njihovih smjesa u vodi, u ovom radu proveli su se laboratorijski testovi toksičnosti s vodenbuhom Daphnia magna, uobičajenim slatkovodnim zooplanktonskim račićem. Daphnia magna izlagala se četirima vrstama MP-a, polistirena (PS), poli(etilen-tereftalat)a (PET), poli(vinil-klorid)a (PVC) i polietilena (PE) veličine čestica 100 – 300, 300 – 500 i 500 – 700 μm, čime se potvrdilo da ove veličine čestica su prevelike za unos u organizam i ne dovode do toksičnog učinka. Zbog toga se ispitao utjecaj manjih čestica PS-a od 0,5 i 2 μm, koje su primijenjene u koncentracijama 0,1; 0,5; 1; 2 i 10 mg/L.
S obzirom da odgovara veličini hrane vodenbuha, potvrđen je toksični učinak čestica veličine 2 μm, koji raste s porastom koncentracije, a učinak na 50 % vodenbuha izračunat kao EC50 vrijednost iznosi 0,02 mg/L. Antivirotici korišteni u pokusu su atazanavir (ATA) koncentracije 0,003 mmol/L te emtricitabin (EMT), nirmatrelvir (NIR), oselfamivir (OSE), ribavirin (RIB) i sofosbuvir (SOF) koncentracije 0,1 mmol/L, koji pri ovim okolišnim koncentracijama nisu imali toksičan učinak. Korišteni antibiotik azitromicin (AZ) ispitivao se u pet koncentracija 0,001; 0,01; 0,1; 0,25 i 0,5 mmol/L, a prema dobivenim rezultatima toksičnost je rasla s porastom koncentracije i učinak na 50 % vodenbuha izračunat kao EC50 vrijednost iznosi 0,6 mmol/L. U binarnim i ternarnim kombinacijama najznačajniji toksični učinak uočen je pri koncentraciji 0,5 mmol/L AZ s PE, odnosno PET, koji je rezultirao samo s 20 % pokretnih vodenbuha. Dobiveni eksperimentalni rezultati obrađeni su korištenjem statističke analize varijance (ANOVA), čime je također potvrđeno da toksični učinak ksenobiotika na Daphnia magna ovisi o koncentraciji i veličina čestica.Pollution of the aquatic ecosystem with xenobiotics, microplastics (MP) and pharmaceuticals is increasing due to anthropogenic influences, such as the excessive use of plastic packaging, industrial development and the consumption of medicines, which consequently leads to their release into the environment. MP is considered a pollutant because it has become a global threat due to its ubiquity, bioinertness, hazard to aquatic organisms, and impact on human health. Pharmaceuticals such as antibiotics and antivirals form a group of pollutants that can seriously threaten the health of non-target organisms. Pollution of the aquatic ecosystem has become a worldwide problem, and scientists, in cooperation with legislative bodies, are looking for solutions to prevent further pollution of the environment. In order to assess the toxicity of MP, antibiotics and antivirals and their mixtures in water, in this work laboratory toxicity tests were conducted with the water flea Daphnia magna, a common freshwater zooplankton crustacean. Daphnia magna was exposed to four types of MP, polystyrene (PS), poly(ethylene-terephthalate) (PET), poly(vinyl-chloride) (PVC) and polyethylene (PE) with particle sizes of 100 – 300, 300 – 500 and 500 – 700 μm, and toxicity testing confirmed that these particle sizes are too large to be taken into the body and cause toxic effect. For this reason, the tocix effect of smaller PS particles of 0,5 and 2 μm, which were applied in concentrations of 0,1; 0,5; 1; 2 and 10 mg/L were estimated. Given that it corresponds to the size of the water flea's food, the toxic effect of particles with a size of 2 μm has been confirmed, which increases with increasing concentration, and the effect on 50 % of water fleas calculated as an EC50 value is 0,02 mg/L. The antivirals used in the experiment are atazanavir (ATA) at a concentration of 0,003 mmol/L and emtricitabine (EMT), nirmatrelvir (NIR), oselfamivir (OSE), ribavirin (RIB) and sofosbuvir (SOF) at a concentration of 0,1 mmol/L, which at these environmental concentrations did not have a toxic effect. The antibiotic azithromycin (AZ) used was tested in five concentrations of 0,001; 0,01; 0,1; 0,25 and 0,5 mmol/L, and according to the obtained results, toxicity increased with increasing concentration and the effect on 50 % of water fleas calculated as EC50 value is 0,6 mmol/L. In binary and ternary combinations, the most significant toxic effect was observed at a concentration of 0,5 mmol/L AZ with PE, or PET, which resulted in only 20 % of motile water fleas. The obtained experimental results were processed using statistical analysis of variance (ANOVA), which also confirmed that toxicity of xenobiotics to Daphnia magna depends on the concentration and particle size
Optimization of photoelectrochemical water splitting performance in the presence of ascorbic acid
No full textCilj ovog rada bio je ispitati fotoelektrokemijski proces dobivanja vodika upotrebom TiO2 i SnS2 elektroda uz askorbinsku kiselinu kao žrtvujuće sredstvo. Sva mjerenja provedena su u otopini 0,1 M NaCl sa i bez askorbinske kiseline. Ispitivanje elektroda provodilo se metodom linearne promjene potencijala (LSV), elektrokemijskom impedancijskom spektroskopijom (EIS), kronoamperometrijom (CA) i mjerenjem potencijala otvorenog kruga (OCP). Adsorpcija askorbinske kiseline na fotokatalitički materijal praćena je metodom UV/VIS spektrofotometrije dok je plinskom kromatografijom određena količina vodika koja se razvija u procesu. Dobivanje vodika se provodilo metodom kronoamperometrije u trajanju od dva sata u atmosferi argona. Vodik je uspješno dobiven, a veće količine dobivene su na SnS2 elektrodi nego na TiO2 elektrodi. Uspoređujući odzive linearne polarizacije osvijetljene i neosvijetljene elektrode, uočava se kako pod djelovanjem svjetla struja raste što znači da su obje elektrode fotoaktivne. Upotrebom askorbinske kiseline dolazi do povećanja fotostruja što je dokaz da askorbinska kiselina djeluje kao žrtvujuće sredstvo. Osim fotostruja, pri potencijalima većim od 0,5 V uočavaju se značajan porast struje koji je posljedica elektrokemijske oksidacije askorbinske kiseline.The aim of this work was to study the photoelectrochemical process of hydrogen production using TiO2 and SnS2 electrodes with ascorbic acid as a sacrificial agent. All measurments were performed in 0.1 M NaCl solution with and without ascorbic acid. The electrodes were tested using linear sweep voltametry (LSV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA) and open circuit potential (OCP) monitoring. The adsorption of ascorbic acid on the photocatalytic material was monitored by using UV/VIS spectrophotometry, while the amount of hydrogen generated in the process was determined by gas chromatograpy. Hydrogen was produced using the chronoamperometry method during two hours in an argon atmosphere. Hydrogen was successfully obtained, and larger amounts were produced in the process involving SnS2 photoelectrode than in the process involving TiO2 photoelectrode. The linear voltammetry responses of illuminated and non-illuminated electrodes indicate that illumination results in a current increase which is the evidence that both electrodes are photoactive. The ascorbic acid addition increases the photocurrent value. The significant current increase in ascorbic acid solution, observed at potentials more positive than 0.5 V, is the result of electrochemical reaction
Application the Full Factorial Plan and Response Surface Methodology to determine the effect of microplastics on healthy and tumor cell lines
No full textPretjerana uporaba plastičnih materijala i loše gospodarenje plastičnim otpadom stvorili su rastući problem u pogledu onečišćenja okoliša te utjecaja na žive organizme koji u njemu žive, pa tako i čovjeka. Poseban naglasak se u sklopu novijih znanstvenih istraživanja stavlja na mikroplastiku, koja nastaje kao posljedica fragmentacije plastičnog otpada uslijed izlaganja okolišnih uvjetima. Ova vrsta plastike predstavlja specifičnu opasnost, budući da se zbog svoje veličine olakšano kreće kroz ekosustave, uklapa u hranidbene lance i akumulira u živim jedinkama na koje potom ima potencijalno štetne učinke. U ovome radu provedeno je ispitivanje učinka mikročestica polistirena na relativno preživljenje humanih plućnih staničnih linija zdravog (WI-38) i tumorskog porijekla (H1299 i A549) u ovisnosti o rasponu veličina čestica mikroplastike, koncentraciji otopina mikroplastike kojim su stanice tretirane i vremenu izlaganja. Kako bi se ustanovilo relativno preživljenje testnih staničnih kultura proveden je MTT test, a programom Desing Expert 7.1.5. određeni su eksperimentalni uvjeti kojima je postignut najštetniji učinak mikroplastike na ispitne stanične linije, odnosno uvjeti pri kojima je relativno preživljenje stanica bilo najniže. Za staničnu liniju WI-38 minimalno preživljenje ustanovljeno je pri: 157,01 μm (veličina čestica PS-a), 0,50 μg/mL (koncentracija otopina PS-a) i 39,74 sata (vrijeme izlaganja), a značajni procesni parametri bili su koncentracija i veličina čestica. Za H1299 najniže preživljenje ostvarilo se pri: 103,11 μm (veličina čestica PS-a), 1,00 μg/mL (koncentracija otopina PS-a) i 24 sata (vrijeme izlaganja), pri čemu su značajni procesni parametri bili koncentracija i vrijeme izlaganja. Stanična linija A549 najmanje preživljenje imala je pri: 200 μm (veličina čestica PS-a), 2,00 μg/mL (koncentracija otopina PS-a) i 51,17 sata (vrijeme izlaganja), dok je značajni procesni parametar bio isključivo vrijeme. Prema dobivenim rezultatima zaključeno je da štetan učinak mikroplastike PS-a u pogledu smanjenja relativnog preživljenja postoji, te da s obzirom na vrstu ispitne stanične linije može ovisiti o veličini čestica PS-a, koncentraciji otopina i vremenu izlaganja.Excessive use of plastic materials and poor management of plastic waste in modern times have created a growing problem in terms of environmental pollution and impact on living organisms that live in it, including humans. As part of recent scientific research, special emphasis is placed on microplastics, which are formed as a result of the fragmentation of plastic waste due to exposure to environmental conditions. This type of plastic represents a specific danger, since due to its size it can easily move through ecosystems, fit into food chains and accumulate in living organisms, on which it can have potentially harmful effects. In this work, the effect of polystyrene microparticles on the relative survival of human lung cell lines of healthy origin (WI-38) and tumor origin (H1299 and A549) was investigated. The dependence of survival on the size range of the microplastic particle, the concentration of the microplastic solution with which the cells were treated and the exposure time was observed. In order to establish the relative survival of the test cell cultures, the MTT test was performed. Program Desing Expert 7.1.5. was used to determine the experimental conditions under which the most harmful effect of microplastics on the test cell lines was achieved. In other words, those were the conditions under which relative cell survival was the lowest. For the WI-38 cell line, minimum survival was found at: 157.01 μm (PS particle size), 0.50 μg/mL (PS solution concentration) and 39.74 hours (exposure time), a significant process parameters were concentration and particle size. For H1299, the lowest survival was achieved at: 103.11 μm (PS particle size), 1.00 μg/mL (PS solution concentration) and 24 hours (exposure time), where the significant process parameters were concentration and exposure time. The A549 cell line had the lowest survival at: 200 μm (PS particle size), 2.00 μg/mL (PS solution concentration) and 51.17 hours (exposure time), while the only significant process parameter was time. According to the obtained results, it was concluded that the harmful effect of PS microplastics in terms of reducing relative survival exists. Also, depending on the test cell culture type, the decrease in survival depends on the size of the PS particle, the concentration of the solution and the exposure time
Prediction of fouling formation in an industrial heat exchanger using machine learning methods
No full textNastajanje naslaga u industrijskim izmjenjivačima topline smanjuje učinkovitost izmjenjivača, povećava operativne troškove, dovodi do veće potrošnje energenata i posljedično povećane emisije CO2. Naslage predstavljaju jedan od najvećih problema u rafinerijskim postrojenjima, a njihovo nastajanje posebno je izraženo u sekciji za predgrijavanje sirove nafte. Kako bi se optimiziralo održavanje izmjenjivača topline i postigle financijske uštede, potrebno je kontinuirano pratiti nastajanje naslaga u izmjenjivačima topline. Zbog složenog sastava sirove nafte, nepoznatog mehanizma nastajanja naslaga i promjenjivih procesnih uvjeta ne postoji opće prihvaćeni empirijski ili polu-emipirijski model za praćenje nastajanja naslaga u izmjenjivačima topline u sekciji za predgrijavanje. Stoga se sve češće koriste modeli temeljeni na podacima. U ovom diplomskom radu, razvijeni su modeli umjetnih neuronskih mreža i modeli ekstremnog gradijentnog pojačavanja za predviđanje izlazne temperature tople i hladne struje čistog izmjenjivača topline. Modeli su razvijeni koristeći fizikalno-kemijska svojstva sirove nafte i kontinuirane praćene procesne varijable iz rafinerijskog postrojenja. Postupna razlika između predviđenih i stvarnih temperatura ukazuje na smanjenje učinkovitosti izmjenjivača topline zbog prisutnosti naslaga. Najbolji modeli detaljnije su analizirani, a njihove izlazne temperature korištene su za izračun fouling faktora, koji pruža kvantitativan uvid u proces nastajanja naslaga. Koristeći ovu metodologiju može se dobiti uvid u trend nastajanja naslaga. Primjena razvijenih modela na rafinerijskom postrojenju omogućila bi kontinuirano praćenje nastajanja naslaga u izmjenjivačima topline, čime bi se postigle značajne financijske uštede i osiguralo pravovremeno čišćenje izmjenjivača.Fouling formation in industrial heat exchangers reduces their efficiency, increases operational costs, leads to higher energy consumption which consequently raises CO2 emissions. Fouling is one of the biggest problems in refineries, particularly pronounced in crude oil preheating plant. To optimize the maintenance of heat exchangers and achieve financial savings, it is essential to continuously monitor fouling formation in heat exchangers. Due to the complex composition of crude oil, the unknown mechanisms of fouling formation, and variable process conditions, there is no generally accepted empirical or semi-empirical model for monitoring fouling in heat exchangers within the preheat train. Therefore, it has become a common practice to use data-driven models. In this master's thesis, artificial neural network and Extreme Gradient Boosting models have been developed to predict the outlet temperatures of the hot and cold streams of the clean heat exchanger. These models were developed using the physicochemical properties of crude oil and continuously monitored process variables from the refinery. The gradual difference between the predicted and actual temperatures indicates a reduction in the efficiency of the heat exchanger due to the presence of fouling. The best models were analyzed in detail, and their outlet temperatures where used to calculate the fouling factor, which provides quantitative insight into the fouling formation process. Using this methodology, it is possible to gain insight into the trend of fouling formation. The application of the developed models in the refinery would enable continuous monitoring of fouling in heat exchangers, resulting in significant financial savings and ensuring timely cleaning of the exchangers
Korozijska i mikrobiološka otpornost modificirane epoksidne prevlake za zaštitu cijevi
No full textOne of the leading issues in industry and municipal infrastructure is the occurrence of corrosion damage, which poses a serious challenge due to its ability to cause significant financial losses and operational disruptions. This process not only reduces the lifespan of metal structures but also increases the costs of maintenance, repairs, and replacements, thereby directly impacting on the economic sustainability of projects. In response to this challenge, various surface protection methods have been developed that are based on isolating the metal surface from the aggressive environment through protective layers, which can be in the form of coatings, linings, or surface treatments. This work focuses on corrosion protection of underground pipes, which are particularly exposed to aggressive conditions such as seawater and wastewater, microbiological environments, high humidity, and cyclic temperature changes. For this purpose, a multi-layer coating system made from chemically inert high-molecular polymeric materials containing epoxy groups is commonly used.
Over the time, damage occurs to the epoxy coating, leading to the formation of micropores, microcracks, and swelling, making it necessary to further modify such organic coatings to extend the lifespan of the protection they provide. To expand existing knowledge, this doctoral thesis investigates an active nanocomposite coating for the corrosion protection of drainage pipes. The examined system includes an epoxy matrix and fillers in the form of metal nanoparticles, whose role is to improve the coating's corrosion and microbiological resistance. The experimental work is based on a series of input variables, which include the testing of different types and concentrations of metal nanoparticles, methods of their incorporation into the epoxy coating, and the interaction between the nanoparticles and the epoxy paint or pure epoxy resin. The effectiveness of the developed coatings was tested on a grey cast iron substrate. The addition of nanoparticles improved some of the key properties of the epoxy coating. The structural and morphological characteristics of the nanoparticles, unmodified epoxy coating, and nanocomposite coatings were determined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Based on the tested physical properties, it was found that the addition of nanoparticles improves one of the most critical parameters for coating durability, namely, the adhesion of the coating to the metal surface. Special attention was given to enhancing the anticorrosion and antibacterial properties of the modified coatings. For this purpose, three types of metal nanoparticles were used: aluminum, silver, and nickel. By using the electrochemical impedance spectroscopy, it was found that the nanocomposite coating containing 1% silver nanoparticles exhibits the best anticorrosive properties, followed by the nanocomposite coatings with nickel and aluminum. Additionally, the antibacterial properties of the epoxy coating and nanocomposite coatings were determined, revealing that the nanocomposite coatings with aluminum and silver yielded the best results, while the nanocomposite coating with nickel had minimal antibacterial activity. The nanocomposite with 1% aluminum nanoparticles showed significant migration, while the nanocomposites with silver and nickel nanoparticles exhibited the lowest migration values from the epoxy coating into wastewater. The amount of migrated aluminum nanoparticles initially increased gradually but reached a constant concentration of aluminum (1 mg/L) after 10 days of exposure to wastewater.
The surface of the nanocomposite coating with 1% aluminum nanoparticles was analyzed by using the scanning electrochemical microscopy, and it was found that only these nanoparticles were capable of forming a passive oxide film on their surface, thus preventing the degradation of the coating. Therefore, samples modified with aluminum nanoparticles were tested in accelerated corrosion tests, including salt spray tests, high humidity conditions, and in a climate chamber. Based on the conducted research, a nanocomposite coating containing aluminum nanoparticles was developed. These nanoparticles can migrate and oxidize in the event of corrosion or bacterial attack, thereby improving the corrosion and microbiological stability of the epoxy coating, with potential commercialization that could ultimately contribute to a longer lifespan of buried pipes.Jedan od vodećih problema u industriji i komunalnoj infrastrukturi je pojava korozijskog oštećenja koje predstavlja ozbiljan izazov jer uzrokuje velike financijske gubitke i prekide u radu. Ovaj proces ne samo da smanjuje vijek trajanja metalnih konstrukcija, već i povećava troškove održavanja, popravaka i zamjene, čime direktno utječe na ekonomsku održivost projekata. Kao odgovor na ovaj izazov, razvile su se različite metode površinske zaštite koje se baziraju na odvajanju površine metala od agresivne okoline pomoću zaštitnih slojeva, koji mogu biti u obliku prevlaka, obloga ili tretmana površine. U fokusu ovog rada je korozijska zaštita podzemnih cijevi koje su posebno izložene agresivnim uvjetima, poput morske i otpadne vode, mikrobiološke atmosfere, visoke vlage, te cikličkih promjena temperature.
U tu svrhu uobičajeno se koristi višeslojni sustav prevlaka napravljen od kemijskih inertnih visokomolekulskih polimernih materijala koji sadrže epoksidne skupine. Tijekom vremena eksploatacije dolazi do oštećenja epoksidne prevlake i nastanka mikropora, mikropukotina i bubrenja, zbog čega je potrebno dodatno modificirati takvu organsku prevlaku kako bi se produljio vijek zaštite koju pruža. U cilju proširenja dosadašnjih saznanja, u ovom doktorskom radu istraživana je aktivna nanokompozitna prevlaka za zaštitu odvodnih cijevi od korozije. Ispitivani sustav uključuje epoksidnu matricu i punila u obliku metalnih nanočestica čija je uloga poboljšanje korozijske i mikrobiološke otpornosti prevlake Eksperimentalni rad počiva na nizu ulaznih varijabli koje podrazumijevaju ispitivanje različitih vrsta i koncentracija metalnih nanočestica, te metode njihove ugradnje unutar epoksidne prevlake, kao i međudjelovanje između nanočestica i epoksidne boje ili čiste epoksidne smole.
Učinkovitost zaštite razvijenih prevlaka ispitana je na podlozi od sivog lijeva. Dodavanje nanočestica poboljšalo je neka od ključnih svojstava epoksidne prevlake. Strukturne i morfološke karakteristike nanočestica, nemodificirane epoksidne prevlake i nanokompozitnih prevlaka određene su primjenom pretražne elektronske mikroskopije (SEM) i disperzivne rendgenske spektroskopije (EDS). Na temelju ispitanih fizikalnih svojstava, utvrđeno je da s dodatkom nanočestica poboljšava se jedan od najvažnijih parametara za trajnost prevlake, tj. povećava se prionjivost prevlake uz metalnu površinu. Posebna pozornost posvećena je poboljšanju antikorozijskih i antibakterijskih svojstava modificiranih prevlaka. U tu svrhu korištene su tri vrste metalnih nanočestica: aluminij, srebro i nikal. Pomoću elektrokemijske impedancijske spektroskopije, utvrđeno je da nanokompozitna prevlaka koja sadrži 1% nanočestica srebra pokazuje najbolja antikorozivna svojstva, nakon čega slijedne nanokompozitne prevlake s niklom i aluminijem. Osim toga, određena su i antibakterijska svojstva epoksidne prevlake i nanokompozitnih prevlaka, te je ustanovljeno da nanokompozitna prevlaka s aluminijem i srebrom daju najbolje rezultate, dok nanokompozitna prevlaka s niklom ima vrlo malo antibakterijsko djelovanje. Nanokompozit s 1% aluminijevih nanočestica pokazao je značajnu migraciju, dok su nanokompoziti s nanočesticama srebra i nikla pokazali najmanju vrijednost migracije iz epoksidnog premaza u otpadnu vodu. Količina migriranih nanočestica aluminija u početku je postupno rasla, ali nakon 10 dana izloženosti u otpadnoj vodi poprimila je konstantnu vrijednost koncentracije aluminija (1 mg/L). Pomoću pretražne elektrokemijske mikroskopije analizirana je površina nanokompozitne prevlake s 1% aluminijevih nanočestica, te je ustanovljeno da su jedino ove nanočestice bile sposobne stvoriti pasivni oksidni film na svojoj površini i na taj način spriječiti degradaciju prevlake. Stoga su uzorci modificirani aluminijevim nanočesticama ispitani u ubrzanim korozijskim testovima, uključujući ispitivanja u slanoj magli, uvjetima visoke vlažnosti i u klima komori.
Na temelju provedenih istraživanja razvijena je nanokompozitna prevlaka koja sadrži nanočestice aluminija, koje mogu migrirati i oksidirati u slučaju korozijskog i bakterijskog napada i tako poboljšati korozijsku i mikrobiološku stabilnost epoksidne prevlake, a čija bi potencijalna komercijalizacija u konačnici mogla pridonijeti dužem životnom vijeku ukopanih cijevi
Persistent organic pollutants in freshwater: spatial distribution and risk analysis
No full textOvaj diplomski rad usredotočen je na proučavanje postojanih organskih ončišćivala (engl. persistent organic pollutants, POPs), stavljajući naglasak na njihove osnovne karakteristike te ekotoksikološke rizike koje predstavljaju. U radu su detaljno analizirani poliklorirani bifenili (PCB), organoklorni pesticidi (OCP) i policiklički aromatski ugljikovodici (PAH) kao primjeri POPs-ova. Inovativni aspekt ovog rada je primjena in silico modeliranja, uključujući prediktivnu toksikologiju i napredne statističke analize, kako bi se poboljšalo razumijevanje i predviđanje toksikoloških svojstava ovih onečišćujućih tvari. Upotrebom VEGA QSAR modela analizirana je toksičnost, postojanost i bioakumulacija u sedimentima Hrvatske, koja je zbog svojih bogatih vodnih resursa idealna za proučavanje utjecaja POPs-ova. Sedimenti služe kao indikator za procjenu onečišćenja zahvaljujući svojoj sposobnosti akumulacije tvari.
Iako postoje određena mjerenja, podaci o rasprostranjenosti i koncentracijama PCB-ova i OCP-ova su ograničeni, što ističe potrebu za daljnjim istraživanjima. Napredak ovog rada leži u primjeni sofisticiranih analitičkih metoda, uključujući kemometrijske pristupe, kao što su analiza glavnih komponenata (PCA) i hijerarhijska klaster analiza (HCA), koje omogućuju detaljnu obradu i interpretaciju prikupljenih podataka. Ovi pristupi omogućavaju ne samo identifikaciju i kvantifikaciju prisutnosti spojeva u sedimentima, već i dubinsko razumijevanje njihove distribucije, transporta i ekotoksikološkog utjecaja na akvatične ekosustave.
Kroz temeljitu analizu uzoraka sedimenta prikupljenih iz različitih dijelova Hrvatske,
rad istražuje regionalne razlike u koncentracijama i potencijalnim izvorima promatranih onečišćujućih tvari, te evaluira rizike koje one predstavljaju za okoliš i zdravlje ljudi. Zaključno, rad pridonosi značajnom napretku u razumijevanju ekotoksikoloških rizika povezanih s postojanim organskim onečišćujućim tvarima u hrvatskim slatkovodnim ekosustavima, naglašavajući potrebu za daljnjim istraživanjima i implementacijom adekvatnih mjera zaštite.This thesis is focused on the study of persistent organic pollutants (POPs), emphasizing their basic characteristics and the ecotoxicological risks they pose. It provides a detailed analysis of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons (PAHs) as examples of POPs. An innovative aspect of this work is the application of „in silico“ modeling, including predictive toxicology and advanced statistical analyses, to enhance the understanding and prediction of the toxicological properties of these pollutants. The toxicity, persistence, and bioaccumulation in Croatian sediments, which are ideal for studying the impact of POPs due to the country's rich water resources, were analyzed using the VEGA QSAR model. Sediments serve as an indicator for pollution assessment thanks to their ability to accumulate substances. While certain measurements exist, data on the prevalence and concentrations of PCBs and OCPs are limited, highlighting the need for further research. This work advances by applying sophisticated analytical methods, including chemometric approaches such as principal component analysis (PCA) and hierarchical cluster analysis (HCA), which allow for a detailed processing and interpretation of collected data. These approaches enable not only the identification and quantification of compounds in sediments but also a deep understanding of their distribution, transport and ecotoxicological impact on aquatic ecosystems. Through a thorough analysis of sediment samples collected from various parts of Croatia, the study explores regional differences in concentrations and potential sources of the observed pollutants and evaluates the risks they pose to the environment and human health. In conclusion, this work contributes significantly to the understanding of the ecotoxicological risks associated with persistent organic pollutants in Croatian freshwater ecosystems, underscoring the need for further research and the implementation of adequate protection measures
Preparation and properties of chitosan-based hydrophobic coatings
No full textNapredak u razvoju prirodnih vlakana i kompozitnom inženjerstvu pruža značajnu priliku za dobivanje novih materijale iz obnovljivih izvora, koji su u prirodi biorazgradivi. Dostupnost plastike u okolišu, niska prostor odlagališta , emisije iz spaljivanja i opasnosti od gutanja ovih materijala potaknuo razvoj biorazgradive plastike. Razgradivim polimernim biomaterijalima se daje prednost jer ti materijali imaju specifična fizikalna, kemijska, biološka,biomehanička i razgradna svojstva. Širok raspon prirodnih ili sintetskih biopolimera, koji se mogu podvrgnuti hidrolitičkoj ili enzimskoj razgradnji, su istraživani za mnoge primjene. Područje sve većeg interesa je priprema antimikrobnih jestivih filmova i premaza gdje hitozan ima važnu ulogu zbog svojih dobro dokumentiranih antimikrobnih svojstava. Hitozan je prirodni polimer dobiven deacetilacijom hitina, koji je drugi najzastupljeniji biopolimer u prirodi nakon celuloze. Kao kombinacija svojstava hitozana kao što su sposobnost vezanja vode, sposobnost vezanja masti, bioaktivnost, biorazgradivost, netoksičnost, biokompatibilnost, ubrzanje cijeljenja rana i antifungalnog djelovanja, hitozan i njegovi modificirani analozi pokazali su mnoge primjene u medicini, kozmetici, poljoprivredi, sustavima za biokemijske separacije, biomaterijalima i sustavima za kontrolirano otpuštanja lijeka. U ovom radu pripravljene su prevlake hitozana pomoću otopine 1N octene kiseline. Provedena su ispitivanja površinskih karakteristika primjenom tehnike kontaktnog kuta. Toplinska svojstva ispitivana su primjenom diferencijalne pretražne kalorimetrije i termogravimetrijske analize. Provedena je infracrvena spektroskopija s Fourievom transformacijom te mjerenje propusnosti vodene pare.Recent advances in natural fiber production and composite engineering provide a significant possibility for novel materials made from renewable resources that are biodegradable in nature. The availability of plastics in the environment, limited landfill space, emissions from incineration, and the dangers of ingestion from these materials have all prompted the creation of biodegradable polymers. Polymeric biomaterials that degrade are desirable because they have certain physical, chemical, biological, biomechanical, and degrading features. Many applications are being researched for a wide spectrum of natural or synthetic biopolymers capable of hydrolytic or enzymatic breakdown. Another developing area of interest is the development of antimicrobial edible films and coatings, in which chitosan plays an essential role due to its well-documented antibacterial characteristics. Chitosan and its modified analogs have many applications in medicine, cosmetics, agriculture, biochemical separation systems, biomaterials, and drug controlled release systems due to their combination of properties such as water binding capacity, fat binding capacity, bioactivity, biodegradability, nontoxicity, biocompatibility, wound healing acceleration, and antifungal activity. In this work, chitosan coatings were prepared from 1N-acetic acid solution. The composite coatings were investigated for their surface properties by applying the contact angle technique. The thermal properties were determined by differential scanning calorimetry and thermal conductivity. Infrared spectroscopy with Fourier transformation and measurement of water vapor permeability were performed
The comparison of graphite and lithium titanate as intercalating anode materials for Li-ion batteries
No full textSvrha ovog rada bila je pripraviti elektrode od grafita i litijeva titanata (LTO) te ih testirati za primjenu u litij ionskim galvanskim člancima. Elektrode su dobivene prevlačenjem paste od aktivnih materijala, veziva i aditiva na strujni kolektor od bakrene folije s tankim slojem vodljivog ugljika. Litij ionski galvanski članci priređeni su kao dugmasti članci u kućištu od nehrđajućeg čelika i u komercijalnoj El-Cell ćeliji. Elektrokemijska testiranja provedena su u dvo-elektrodnom i tro-elektrodnom sustavu elektrokemijskim metodama cikličke voltametrije, pražnjenja/punjenja članka i elektrokemijske impedancijske spektroskopije. Za određivanje veličine čestica korišteno je dinamičko raspršenje svjetlosti. Ciklički voltamogram za LTO pokazuje jasne strujne vrhove bez difuzijskog repa što znači da je brzina interkalacije litijevih iona veća od brzine izmjene elektrona. Za grafit se može vidjeti da je proces interkalacije stupnjevit jer se on mora strukturno reorganizirati što nije slučaj kod LTO-a, a odvija se pri mnogo nižim potencijalima od LTO što pogoduje stvaranju SEI sloja koji uzrokuje značajan pad kapaciteta u prvom ciklusu punjenja/pražnjenja. Kod LTO je pad kapaciteta u prvom ciklusu znatno manje izražen. Naponi punjenja/pražnjenja za LTO su relativno stabilni u cijelom području rada sve dok se materijal u potpunosti ne potroši, dok su kod grafita u stalnom porastu prilikom punjenja i padu prilikom pražnjenja. S brojem ciklusa punjenja i pražnjenja, kulonske učinkovitosti teže jedinici. Spektri elektrokemijske impedancijske spektroskopije opisali su ponašanje elektroda prije i poslije cikličke voltametrije i dokazali povećanje polarizacijskog otpora i smanjenje brzine difuzije litijevih kationa kod LTO elektrode, a kod grafitne elektrode je rastao otpor SEI sloja i polarizacijski otpor. Testiranja u tro-elektrodnim sustavima omogućila su istovremeno praćenje potencijala radne elektrode i protuelektrode (Li) uz pomoć litijeve referentne elektrode. Dobiveni rezultati naponskih profila i specifičnih kapaciteta nisu pokazali značajna odstupanja u odnosu na dvo-elektrodne sustave. Dinamičko raspršenje svjetlosti pokazalo je nešto veću uniformnost i veličinu čestica kod LTO nego grafita.The purpose of this work was to prepare graphite and lithium titanate (LTO) electrodes and test them for their use in Li-ion batteries. Electrodes were obtained by coating a paste consisting of active material, binder and a conductive additive on a current collector made of copper foil with a thin layer of conductive carbon. Li-ion cells were prepared as coin cells in a stainless steel case and in a commercial El-Cell. Electrochemical tests were performed in a two-electrode and three-electrode systems using cyclic voltammetry, constant current discharge/charge and electrochemical impedance spectroscopy. Dynamic light scattering was used to determine the particle size. The cyclic voltammogram for LTO shows current peaks without a diffusion tail, which means that the rate of intercalation of lithium ions is higher than the rate of charge transfer. For graphite, it can be seen that the intercalation process is gradual due to the structural reorganization of the active material. It also takes place at much lower potentials than that of LTO, which favours the SEI formation. The formations of SEI layer at graphite electrode is highly pronounced in the first charging/discharging cycle, leading to the deterioration of capacity. With LTO, the drop in capacity is much less pronounced. Stable discharge profiles were observed for LTO, while for graphite the voltages were continuously rising (charging) and falling (discharging). Coulombic efficiencies approached a value of 1 with every successive charging/discharging cycle. Electrochemical impedance spectroscopy spectra described the behavior of the electrode before and after cyclic voltammetry and proved an increase in polarization resistance and a decrease of diffusion rate of lithium cations in the case of the LTO electrode, while the resistance of the SEI and polarization resistance increased in the case of the graphite electrode. Three-electrode systems enabled simultaneous monitoring of the working electrode and the counter electrode (Li) with the help of a lithium reference electrode.
The obtained results of voltage profiles and specific capacities did not show significant deviations in relation to two-electrode systems. Dynamic light scattering showed slightly higher uniformity and bigger particle size in LTO than graphite
Selection of a system for spherical crystallization
No full textKristalizacija je jedan od najvažnijih procesa u farmaceutskoj industriji budući da se većina djelatnih tvari proizvodi u kristalnom obliku. Sferičnom kristalizacijom omogućava se istodobno odvijanje kristalizacije i aglomeracije što rezultira formiranjem kristalnih sfernih oblika koji se mogu direktno tabletirati što pogoduje smanjenju broja koraka pri formulaciji lijeka. Ceritinib je djelatna tvar lijeka Zykadia® koji se koristi za liječenje odraslih osoba s metastatskim karcinomom pluća te prema BCS klasifikaciji djelatnih tvari spada u IV. skupinu. Svrha ovoga rada bila je pronaći optimalan sustav otapala i metodu za dobivanje sferičnih kristala ceritiniba te ispitat njihov utjecaj na oblik i strukturu kristala. Preliminarnim istraživanjima određeno je s kojim otapalima, antiotapalima, kapljevinama za premošćivanje i aditivima te u kojim omjerima će se provoditi sferična kristalizacija. Provedene su tri metode sferične kristalizacije, osim klasične sferične aglomeracije i kvazi-emulzijske difuzije otapala isprobana je i kombinacija ovih dvaju metoda. Kao najuspješniji sustav za provedbu sferične aglomeracije pokazao se THF-voda-heptan, za provedbu QESD-a THF-voda-PVP, a za kombiniranu metodu sustav THF-voda-heptan-PVP. Dobivenim sferičnim kristalima ispitana je morfologija putem optičkog mikroskopa kao i njihova struktura metodom rendgenske difrakcije.Crystallization is one of the most important processes in the pharmaceutical industry since most active substances are produced in crystalline form. Spherical crystallization allows for the simultaneous development of crystallization and agglomeration, resulting in the generation of crystalline spherical forms that can be directly tableted, minimizing the number of steps in the drug formulation process. Ceritinib is the active substance of the drug Zykadia®, which is used for the treatment of adults with metastatic lung cancer. According to the BCS classification of active substances, it belongs to the IV. group. The purpose of this work was to find an optimal solvent system and method for obtaining ceritinib spherical crystals and to examine their influence on the size, shape, and structure of the crystals. Preliminary research has determined with which solvents, antisolvents, bridging liquids, and additives and in what proportions spherical crystallization will be carried out. Three methods were implemented, in addition to classical spherical agglomeration and quasi-emulsion diffusion of solvents. A combination of these two methods was also tried.
The THF-water-heptane system has been shown to be the most successful for spherical aglomeration, the THF-water-PVP for QESD, and the THF-water-heptane-PVP for a combination of methods. The obtained spherical crystals were examined for their morphology using an optical microscope as well as their structure using the X-ray diffraction method