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Synthesis of different carbon nanostructures by controlling the deposition parameters using the spark ablation method
No full textAblacija iskrom postaje sve popularnija tehnika za sintezu ugljikovih nanostruktura zbog niza prednosti koje pruža, uključujući jednostavnost, ekonomičnost te visoku kontrolu procesa proizvodnje. Ova tehnika, koja se temelji na aerosolnoj ablaciji materijala u prisutnosti inertnog plina, omogućuje dobivanje raznovrsnih ugljikovih nanostruktura kontrolom parametara depozicije. U okviru ovog rada, provedena je sinteza dva uzorka ugljikovih nanostruktura, pri čemu je jedini promjenjivi parametar bio odabir vrste plina prisutnog tijekom procesa ablacije. Prvi uzorak sintetiziran je u atmosferi argona, dok je drugi uzorak sintetiziran u atmosferi dušika. Nakon sinteze, dobiveni uzorci detaljno su karakterizirani primjenom metoda analize površinskih svojstava kao što su AFM (eng. Atomic Force Microscopy), SEM (eng. Scanning Electron Microscopy) i BET (Brunauer-Emmett-Teller) analiza.Spark ablation is becoming an increasingly popular technique for synthesis carbon nanostructures due to a range of advantages it offers, including simplicity, cost-effectiveness, and high control over the production process. This technique, based on aerosol ablation of materials in the presence of an inert gas, enables the production of diverse carbon nanostructures by controlling deposition parameters. In the context of this study, synthesis of two samples of carbon nanostructures was conducted, where the only variable parameter was selection of the gas type during the ablation process. The first sample was synthesized in an argon atmosphere, while the second sample was synthesized in a nitrogen atmosphere. After the synthesis, the obtained samples were thoroughly characterized using surface analysis methods such as AFM (Atomic Force Microscopy), SEM (Scanning Electron Microscopy), and BET (Brunauer-Emmett-Teller) analysis
Testing of biodegradability of papers with cellulosic pulps of cereal straws
No full textPrekomjerna uporaba sintetičkih materijala i posljedice njihove trajnosti u okolišu potaknula je razvoj novih, održivih materijala dobivenih iz lignocelulozne biomase. Celulozna vlakna dobivena iz slame žitarica imaju potencijal za različite primjene, uključujući proizvodnju papira i tekstila. Cilj ovog istraživanja bio je ispitati biorazgradivosti i ekotoksičnost neotisnutih i otisnutih papira s celuloznom pulpom slame žitarica. Pokus biorazgradnje papira proveden je u uzorku vrtnog tla s dodatkom suspenzije mješovite kulture bakterije Pseudomonas aeruginosa i plijesni Trichoderma sp., pri čemu su praćeni gubitci u masi te promjene u strukturi papira optičkim mikroskopom. Dobiveni rezultati ukazuju da se papir na koji nije otisnuta boja bolje biorazgradio od otisnutog papira. Otisnuti i neotisnuti papiri nisu se pokazali ekotoksičnim prema vodenoj leći Lemna minor.The excessive use of synthetic materials and their long-term impact on the environment have spurred the development of new, sustainable materials sourced from lignocellulosic biomass. Cellulose fibers obtained from cereal straw have emerged as a promising candidate for various applications, including paper and textile manufacturing. This study aimed to assess the biodegradability and ecotoxicity of papers with cereal straw pulp, both printed and unprinted. Biodegradation experiments were conducted using a garden soil sample supplemented with a mixed culture of bacteria Pseudomonas aeruginosa and fungi Trichoderma sp. The experiments monitored mass losses and structural changes in the paper using a light microscope. The results indicate that unprinted paper exhibited better biodegradability compared to printed paper. Moreover, neither printed nor unprinted paper showed ecotoxic effects on Lemna minor
Development of methods for immobilization of photocatalysts on various solid supports
No full textIdealni pesticidi bi trebali biti štetni samo za ciljane organizme, biorazgradivi, u odgovarajućoj mjeri ekološki prihvatljivi te ne bi smjeli dospijevati u podzemne vode. Međutim, to je rijetko slučaj te široka upotreba pesticida u modernoj poljoprivredi izaziva sve veću zabrinutost. Otpadne vode, koje često sadrže tragove pesticida, podvrgavaju se različitim metodama pročišćavanja. No, uklanjanje pesticida iz otpadnih voda konvencionalnim metodama predstavlja izazov radi njihove visoke stabilnosti. Zbog toga se kao alternativa konvencionalnim metodama sve češće koriste napredni oksidacijski procesi, posebice heterogena fotokataliza. Cilj ovog rada bio je istražiti fotokatalitičku razgradnju neonikotinoidnog insekticida imidakloprida u vodenoj otopini primjenom TiO2 fotokatalizatora vezanih za perlitni nosač. Kao modelna komponenta korišten je imidakloprid, a eksperiment je proveden u čaši koja simulira kotlasti (šaržni) reaktor s recirkulacijom reakcijske smjese.
U eksperimentima je korišten heterogeni fokatalizator, a radi se o UV-C modificiranom TiO2 koji je imobiliziran na granulama perlita. Statistički plan eksperimenta dobiven je pomoću softverskog paketa Design Expert, a ispitan je utjecaj pH, intenziteta zračenja i tipa katalizatora na učinkovitost reakcije. Proces razgradnje imidakloprida bio je praćen primjenom visokoefikasne tekućinske kromatografije. Na temelju prikupljenih eksperimentalnih podataka, izračunate su konverzije fotokatalitičke razgradnje i konstante brzine reakcije, koristeći se Langmuir-Hinshelwoodovim kinetičkim modelom reakcije. Rezultati istraživanja pokazali su da vrsta katalizatora ima značajan utjecaj na konverziju reakcije. Najveća konverzija postignuta je koristeći heterogeni katalizator s perlitnim nosačem veličine čestica 2,5 mm koji je bio podvrgnut metodi impregnacije dvaput, uz najveći intenzitet zračenja te pri teorijski najoptimalnijem pH za fotokatalitičke reakcije.Ideal pesticides should be harmful only to the target organisms, biodegradable, environmentally acceptable to the appropriate extent, and should not reach groundwater. However, this is rarely the case and the widespread use of pesticides in modern agriculture is causing increasing concern. Wastewater, which often contains traces of pesticides, is subjected to various purification methods. However, the removal of pesticides from wastewater using conventional methods is a challenge due to their high stability. This is why advanced oxidation processes, especially heterogeneous photocatalysis, are increasingly being used as an alternative to conventional methods. The aim of this study was to investigate the photocatalytic degradation of the neonicotinoid insecticide imidacloprid in an aqueous solution using a TiO2 photocatalyst attached to a pearlite carrier. Imidacloprid was used as a model component, and the experiment was conducted in a beaker simulating a boiler (batch) reactor with recirculation of the reaction mixture. A heterogeneous focal catalyst was used in the experiments, namely UV-C modified TiO2 immobilized on pearlite granules. Statistical experiment plan obtained using the Design Expert software package, and the influence of pH, radiation intensity and catalyst type on reaction efficiency was tested. The degradation process of imidacloprid was monitored using high-performance liquid chromatography. Based on the collected experimental data, photocatalytic degradation conversions and reaction rate constants were calculated using the Langmuir-Hinshelwood reaction kinetic model. The research results showed that the type of catalyst has a significant influence on the conversion of the reaction. The highest conversion was achieved using a heterogeneous catalyst with a pearlite support with a particle size of 2,5 mm that was subjected to the impregnation method twice, with the highest radiation intensity and at the theoretically most optimal pH for photocatalytic reactions
Optimization of the sample preparation procedure for chromatographic analysis of N-nitrosamine
No full textN-nitrozamini su spojevi opće kemijske strukture R1N(-R2)-N=O, a nastaju reakcijama oksidacije sekundarnih ili tercijarnih amina uz pomoć nitrozacijskog sredstva. Pokazujući mutageno i kancerogeno djelovanje na različite organe i tkiva kod ljudi, posljednjih godina postaju predmetom brojnih analitičkih ispitivanja. Upravo provođenje analitičkih ispitivanja predstavlja ključ za sprječavanje nastanka N-nitrozamina i njihova uklanjanja iz vode. U ovome radu ispitivano je sedam N-nitrozamina: N, N-dibutilnitrozni amid (NDBA), N, N-dietilnitrozni amid (NDEA), N, N-dimetilnitrozni amid (NDMA), N, N-dipropilnitrozni amid (NDPA), 4-nitrozomorfolin (NMOR), 1-nitrozopiperidin (NPIP) te 1-nitrozopirolidin (NPYR). Kako bi se zadovoljio cilj rada u vidu optimizacije postupka pripreme uzorka za kromatografsku analizu N-nitrozamina primijenjen je Box-Behnkenov dizajn eksperimenata s tri numeričke varijable na tri razine u kombinaciji s metodom odzivnih površina (RSM). Uzorci vode pripremljeni su ekstrakcijom čvrstom fazom (SPE) uz upotrebu kokosova ugljena kao sorbensa. Nakon provedbe numeričke optimizacije kao optimalni uvjeti ekstrakcije čvrstom fazom primijenjeni su volumen uzorka od 300 ml, volumen eluensa od 12 ml te vrijeme sušenja sorbensa od 10 min. Provedena su dva eksperimenta pri optimalnim uvjetima, pri čemu je jedan uključivao uparavanje otapala iz uzorka na rotacijskom uparivaču, a drugi uparavanje otapala iz uzorka u struji dušika. Prisutnost N-nitrozamina u dobivenim ekstraktima u oba slučaja potvrđena je tekućinskom kromatografijom visoke djelotvornosti uz detektor s nizom dioda (HPLC-DAD) gdje je primjenom gradijentnog eluiranja uz protok od 0,5 ml/min provedena uspješna separacija svih sedam N-nitrozamina na kromatografskoj koloni Kinetex C18 uz korištenje MilliQ vode i acetonitrila kao pokretnih faza. Uspoređujući dobivene odzive odnosno vrijednosti učinkovitosti ekstrakcije moguće je zaključiti kako uparavanje u struji dušika biva učinkovitije za NDMA, NDEA, NDPA i NDBA u odnosu na uparavanje na rotacijskom uparivaču. Gledano s ekonomskog aspekta optimizacijom SPE postupka osigurava se ušteda reagensa i potrošnog materijala, ali i utrošenog vremena samoga znanstvenika.N-nitrosamines are compounds with the general chemical structure R1N(-R2)-N=O that are formed by oxidation reactions of secondary or tertiary amines with the help of a nitrosating agent. Showing mutagenic and carcinogenic effects on various organs and tissues in humans they have become the subject of numerous analytical tests in recent years. Analytical testing is essential to prevent the formation of N-nitrosamines and their removal from water. In this study, seven N-nitrosamines were analysed: N, N-dibutylnitrous amide (NDBA), N, N-diethylnitrous amide (NDEA), N, N-dimethylnitrous amide (NDMA), N, N-dipropylnitrous amide (NDPA), 4-nitrosomorpholine (NMOR), 1-nitrosopiperidine (NPIP) and 1-nitrosopyrrolidine (NPYR). In order to meet the goal of the study in the form of optimization of the sample preparation procedure for the chromatographic analysis of N-nitrosamines, the Box-Behnken design of experiments with three numerical variables at three levels in combination with the response surface methodology (RSM) was applied. Water samples were prepared by solid phase extraction (SPE) using coconut charcoal as a sorbent. After numerical optimization, a sample volume of 300 ml, an eluent volume of 12 ml and a sorbent drying time of 10 min were used as the optimal conditions for solid phase extraction. Two experiments were performed at optimal conditions, one involving the evaporation of the solvent from the sample on a rotary evaporator, and the other the evaporation of the solvent from the sample in a stream of nitrogen. The presence of N-nitrosamines in the obtained extracts in both cases was confirmed by high-performance liquid chromatography with diode array detector (HPLC-DAD) by applying gradient elution at a flow rate of 0,5 ml/min. A successful separation of all seven N-nitrosamines was carried out on the Kinetex C18 chromatographic column using MilliQ water and acetonitrile as mobile phases. By comparing the obtained responses and extraction efficiency values, it is possible to conclude that evaporation in a nitrogen stream is more efficient for NDMA, NDEA, NDPA and NDBA compared to evaporation on a rotary evaporator. From an economic point of view, the optimization of the SPE procedure ensures the saving of reagents and consumables, as well as the time spent by the scientist
Influence investigation of different parameters on photocatalytic degradation of procaine
No full textFarmaceutici su sveprisutni u našem svakodnevnom životu i time vrlo lako dospijevaju u okoliš. Primarni put njihovog ulaska u okoliš je kroz izvore otpadnih voda. Farmaceutici i njihovi metaboliti koji se prenose otpadnom vodom u rijeke i potoke uzrokuju velike probleme u cijelom ekosustavu i vrlo ju je važno prije ispuštanja u vodotokove adekvatno obraditi. Konvencionalni biološki i kemijski postupci obrade otpadnih voda su neučinkoviti zbog bio-nerazgradive prirode mnogih farmaceutika pa se stoga istražuju napredni oksidacijski procesi. Kao jedan od naprednih oksidacijskih procesa u ovom se radu provodi fotokataliza uz katalizator koji je napravljen nanošenjem TiO2 filma na Al2O3 keramičku, pjenastu podlogu pri čemu je kao izvor zračenja korištena UV lampa. U ovom radu ispitan je utjecaj različitih parametara na fotokatalitičku razgradnju prokaina. Prvo je provedena validacija metode za praćenje prokaina u vodi. Nakon toga proveli su se preliminarni eksperimenti kojima se potvrdilo da smanjenje koncentracije prokaina u otopini nije povezano s njegovom hidrolitičkom razgradnjom niti njegovom adsorpcijom na fotokatalizator. Također, određena je i kinetika fotokatalitičke razgradnje prokaina koja se može opisati reakcijom razgradnje prvog reda. Nadalje, provođenjem eksperimenata kojima se ispitao utjecaj pH vrijednosti otopine i koncentracije prokaina određeni su optimalni uvjeti za provođenje fotokatalitičke razgradnje pri čemu koncentracija prokaina iznosi 10 mg/L, a pH vrijednost otopine 10. Ispitivanjem utjecaja slobodnih radikala na mehanizam razgradnje pokazalo se da šupljine imaju značajnu ulogu. Prilikom ispitivanja utjecaja matice vode utvrđeno je da nitrati i kloridi blago usporavaju fotokatalitičku reakciju razgradnje prokaina, a hidrogenkarbonati povećavaju brzinu razgradnje, ali sama promjena koncentracije navedenih tvari u otopini ne utječe na brzinu razgradnje. S druge strane, povećanjem koncentracije huminske kiseline smanjuje se brzina fotokatalitičke razgradnje. Razgradni produkti određeni nakon provođenja eksperimenta pri optimalnih uvjetima su RP-1 s m/z 120 i RP-2 s m/z 138. Na kraju se provela i procjena razvojne toksičnosti, mutagenosti i bioakumulacijskog faktora prokaina i nastalih razgradnih produkata računalnim programom TEST.Pharmaceuticals are ubiquitois in our daily lives and therefore easily enter the environment. They enter the environment primarly through wastewater. Pharmaceuticals and their metabolites that enter rivers and streams with wastewater are a major problem for the entire ecosystem, and it is very important to treat them properly before they enter waterways. Conventional biological and chemical wastewater treatment methods are ineffective due to the biodegradability of many pharmaceuticals, so advanced oxidation methods are being researched. As one of the advanced oxidation methods, photocatalysis is carried out in this work with a catalyst prepared by depositing a TiO2 film on an Al2O3 ceramic foam substrate, using a UV lamp as a radiation source. In this work, the influence of various parameters on the photocatalytic degradation of procaine was investigated. First, the validation of the method for monitoring procaine in water was carried out. Then, preliminary experiments were performed, which confirmed that the decrease of procaine concentration in solution was not related to its hydrolytic degradation or adsorption to the photocatalyst. Moreover, the kinetics of the photocatalytic decomposition of procaine was determined, which can be described by a first-order decomposition reaction. In addition, experiments that investigated the influence of solution pH value and the procaine concentration, the optimal conditions for carrying out photocatalytic decomposition, where the procaine concentration is 10 mg/L and the solution pH is 10. When studying the influence of free radicals on the decomposition mechanism, it was found that the holes played an important role. When the influence of water matrix was studied, it was found that nitrates and chlorides slightly slow down the photocatalytic reaction of procaine decomposition and hydrogen carbonates increase the rate of decomposition, but the mere change of the concentration of the mentioned substances in the solution does not affect the rate of decomposition. Increasing the concentration of humic acid, on the other hand, decreases the photocatalytic degradation rate. The degradation products determined after performing the experiment under optimal conditions are RP-1 with m/z 120 and RP-2 with m/z 138. Finally, an evaluation of the developmental toxicity, mutagenicity, and bioaccumulation factor of procaine and the resulting degradation products was performed using the computer program TEST
Adsorption of the antiozonant by-product of from automobile tires on microplastics in water
No full textAntiozonanti dodaju se automobilskim gumama tijekom vulkanizacije, radi sprječavanja i usporavanja degradacije gume uzrokovane ozonom, čime se pruža zaštita i sigurnost vozača i putnika tijekom vožnje automobilom. 6PPD standardni je antiozonant u automobilskim gumama, ali kada reagira s ozonom nastaje njegov transformacijski produkt
N-(1,3-dimetilbutil)-N'-fenil-p-fenilendiamin-kinon (6PPD-Q). 6PPD kinon ispire se s automobilskih guma i cesta tijekom svakog hidrološkog ciklusa, što dovodi do njegove migracije u prirodne vode. Kada se nalazi u vodenome okolišu pokazuje toksičan utjecaj na razne ribice, račiće i mikroalge, ali uzrokuje i ugibanje određenih vrsta lososa. Mikroplastika pronalazi se u svakodnevno korištenim proizvodima, a zbog neadekvatnog zbrinjavanja njezinog otpada nakon uporabe, migrira u okoliš gdje također onečišćuje prirodne vode. Određeni vodeni organizmi, poput ribica i račića, neselektivno konzumiraju mikroplastiku što uzrokuje kratkotrajne i dugotrajne posljedice na njihov organizam. Budući da mikroplastika ima visoki stupanj adsorpcije, na površinu njezinih čestica mogu se adsorbirati organske onečišćujuće tvari iz okoliša. Adsorpcija je nagomilavanje (akumuliranje) čestica iz susjedne (plinovite ili kapljevite) faze na površinu krute faze, čemu je uzrok djelovanje privlačnih sila između čestica na krutoj površini i čestica iz susjedne faze. Testirana je adsorpcija 6PPD kinona u vodenoj otopini na mikroplastiku PP 0 (nestareni polipropilen) i PP UV 56
(UV stareni polipropilen). Uzorci su snimani na tekućinskom kromatografu visoke djelotvornosti (engl. High Performance Liquid Chromatography, HPLC) kojim je omogućeno određivanje koncentracije 6PPD kinona u vodenoj otopini prije i nakon adsorpcije. Također je testirana i toksičnost čistih otopina 6PPD kinona i mikroplastike te njihove mješavine 24 h nakon adsorpcije na slatkovodnim račićima Daphnia Magna. Rezultati su pokazali da adsorpcija 6PPD kinona na mikroplastiku u oba slučaja slijedi Langmuirov model, odvija se u monosloju te je raspodjela aktivnih mjesta na adsorbensu homogena. Starena mikroplastika (PP UV 56) ima veću adsorpcijsku ravnotežnu konstantu i samim time veći afinitet za adsorpciju 6PPD kinona, nego nestarena mikroplastika (PP 0). Također je ustanovljeno da je potrebna samo četvrtina uzorka čiste otopine 6PPD kinona da bi se postigla 50%-tna inhibicija račića Daphnia Magna. Iako je s usporedbom na navedenu otopinu potreban nešto veći udio uzorka vodene otopine 6PPD kinona s PP 0 i PP UV 56 24 h nakon adsorpcije, one i dalje pokazuju toksičan utjecaj na račiće.Antiozonants are added to car tires during vulcanization, in order to prevent and slow down the degradation of rubber caused by ozone, which enables the protection and safety of drivers and passengers while driving a car. 6PPD is a standard antiozonant in car tires, but when it reacts with ozone, its transformation by-product
N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q) is formed. 6PPD quinone is washed off of car tires and roads during each hydrologic cycle, leading to its migration into natural waters. When found in aquatic environment, 6PPD-Q shows a toxic effect on various fish, cryfish and microalgae, in addition it's deadly for certain types of salmon. Microplastics are found in everyday products, and due to inadequate disposal of their waste after use, they migrate into the environment where they also pollute natural waters. Certain aquatic organisms, such as fish and crayfish, indiscriminately consume it, which causes short-term and long-term consequences for their organisms. Since microplastics has a high value of adsorption capacity, organic pollutants from the environment can be adsorbed on the surface of its particles. Adsorption is accumulation of particles from a neighbouring (gas or liquid) phase on to the surface of the solid phase, which is caused by intermolecular forces of the particles on the solid surface and particles from the adjacant phase. Adsorption of 6PPD quinone in aqueous solution on microplastics PP 0 (unaged polypropylene) and PP UV 56 (UV aged polypropylene) was tested.
The samples were recorded with high performance liquid chromatography (HPLC), which enabled the determination of the concentration of 6PPD quinone in the aqueous solution before and after adsorption. The toxicity of blank solutions of 6PPD quinone and microplastics and their mixtures 24 h after adsorption on the freshwater flea Daphnia Magna was also tested. The results showed that the adsorption of 6PPD quinone on microplastics in both cases follows the Langmuir model, takes place in a monolayer, and the distribution of active sites on the adsorbent is homogeneous. Aged microplastic (PP UV 56) has a higher adsorption equilibrium constant and thus a higher affinity for 6PPD quinone adsorption than unaged microplastic (PP 0). Also, it was shown that only a quarter of a sample of blank 6PPD quinone solution is needed to achieve 50% inhibition of water flea Daphnia Magna. Although a slightly larger fraction of the sample of the aqueous solution of 6PPD quinone with PP 0 and PP UV 56 24 h after adsorption is required compared to the blank solution, they still show a toxic effect on water fleas
New advanced materials inspired by nature
No full textRazvoj biomimetičkih materijala inspiriranih prirodom postaje sve važniji zbog svojih inovativnih primjena. Paukova mreža pokazala se kao jedan od najzanimljivih materijala zbog svojih izvrsnih mehaničkih karakteristika, biokompatibilnosti, adhezijskih i superhidrofobnih svojstava te izvrsne toplinske stabilnosti. Cilj ovog rada je ispitati strukturna i toplinska svojstva paukove svile dobivene sakupljanjem paukovih mreža. Toplinska svojstva određena su diferencijalnom pretražnom kalorimetrijom (DSC) i termogravimetrijskom analizom (TGA), dok su površinske karakteristike analizirane mjerenjem kontaktnog kuta. Sastav i karakteristične skupine prisutne u paukovoj svili (mreži) određene su infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR). Za svaku metodu opisane su teorijske značajke, eksperimentalni uvjeti i rezultati mjerenja. Eksperimentalna analiza pokazala je da je paukova svila izuzetno zanimljiva zbog svoje kompleksne strukture kao i jedinstvenih svojstava, što je čini vrlo zanimljivim materijalom za istraživanje za različite primjene.The development of biomimetic materials inspired by nature is becoming increasingly important due to their innovative applications. Spider silk has proven to be one of the most intriguing materials because of its excellent mechanical properties, biocompatibility, adhesive and superhydrophobic properties, as well as its remarkable thermal stability. The aim of this work is to examine the structural and thermal properties of spider silk obtained by collecting spider webs. Thermal properties were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), while surface characteristics were analyzed by measuring the contact angle. The composition and characteristic groups present in spider silk (web) were determined using Fourier transform infrared spectroscopy (FTIR). For each method, theoretical features, experimental conditions, and measurement results were described. The experimental analysis showed that spider silk is highly interesting due to its complex structure and unique properties, making it a very attractive material for research in various applications
The possibilities of using molecular sieves to adsorb and concentrate CO2 from flue gases
No full textKako bi se ispunili globalni ciljevi postavljeni za smanjenje ugljičnog dioksida (CO2), ključnu ulogu ima hvatanje i skladištenje ugljika. U tom okviru, hvatanje CO2 nakon izgaranja putem adsorpcije smatra se jednim od najperspektivnijih pristupa jer može donijeti značajne energetske uštede u odnosu na standardno hvatanje putem apsorpcije. Do danas, većina istraživačkih napora bila je usmjerena na razvoj novih, naprednih adsorbenta s primarnim ciljem povećanja adsorpcijskog kapaciteta i dugotrajnosti. Rad se bavi istraživanjem adsorpcije CO2 korištenjem PSA sustava, tehnologije koja se smatra ključnom za smanjenje emisija CO2 u postrojenjima za proizvodnju energije. PSA je proces koji koristi promjene tlaka kako bi se odvojile i uklonile željene komponente iz plinovitih smjesa, u ovom slučaju CO2 iz dimnih plinova. U radu se analizira učinkovitost različitih adsorbenata, s posebnim naglaskom na njihov kapacitet adsorpcije, selektivnost prema CO2, te stabilnost tijekom periodičnih ciklusa. Korištenjem naprednih materijala, poput zeolita 5A i 13X, metal-organskog okvira (MOF) PM3, ispituje se mogućnost poboljšanja učinkovitosti PSA sustava.In order to meet the global goals set for reducing carbon dioxide (CO2), carbon capture and storage plays a crucial role. In this context, post-combustion CO2 capture via adsorption is considered one of the most promising approaches, as it can provide significant energy savings compared to standard absorption-based capture. To date, most research efforts have focused on the development of new, advanced adsorbents, with the primary aim of increasing adsorption capacity and longevity. This paper investigates CO2 adsorption using the PSA system, a technology considered essential for reducing CO2 emissions in power generation plants. PSA is a process that uses pressure changes to separate and remove desired components from gas mixtures, in this case, CO2 from flue gases. The paper analyzes the efficiency of different adsorbents, with a particular focus on their adsorption capacity, selectivity towards CO2, and stability during periodic cycles. By utilizing advanced materials such as zeolites 5A and 13X, and the metal-organic framework (MOF) PM3, the potential for improving the efficiency of PSA systems is examined
Cosmetic preparations on a natural basis
No full textOvaj završni rad bavi se istraživanjem prirodnih preparata i njihovom primjenom u kozmetici. U uvodnom dijelu rada definira se pojam prirodnih preparata te se daje povijesni pregled njihovog razvoja. Rad detaljno analizira vrste prirodnih sastojaka koji se koriste u kozmetici i njihove specifične funkcije. Poseban naglasak stavljen je na primjenu prirodnih proizvoda u različitim kozmetičkim funkcijama, uključujući sredstva za izbjeljivanje kože, sredstva protiv starenja, hidratantna sredstva te prirodne mirise. Detaljno je opisan proces proizvodnje prirodnih kozmetičkih proizvoda s posebnim osvrtom na ekstrakciju prirodnih sastojaka, formulaciju kozmetičkih proizvoda i tehnološke aspekte proizvodnje. Rad zaključuje da prirodni preparati imaju značajan potencijal u kozmetičkoj industriji zbog svojih brojnih prednosti, uključujući blagotvorne učinke na kožu i okoliš. Također, ističe se važnost kontinuiranog istraživanja i razvoja novih prirodnih preparata kako bi se zadovoljili sve veći zahtjevi potrošača za prirodnim i sigurnim kozmetičkim proizvodima.This thesis explores natural preparations and their application in cosmetics. The introductory part defines the concept of natural preparations and provides a historical overview of their development. The thesis thoroughly analyzes the types of natural ingredients used in cosmetics and their specific functions. Special emphasis is placed on the application of natural products in various cosmetic functions, including skin whitening agents, anti-aging products, moisturizers, and natural fragrances. The production process of natural cosmetic products is described in detail, with a focus on the extraction of natural ingredients, the formulation of cosmetic products, and technological aspects of production. The thesis concludes that natural preparations have significant potential in the cosmetic industry due to their numerous advantages, including beneficial effects on the skin and the environment.
It also highlights the importance of continuous research and development of new natural preparations to meet the growing demands of consumers for natural and safe cosmetic products
Cycloaddition of furfurylguanidines and derivatives of acetylenedicarboxylic acid. Experimental and computational study
No full textU ovom radu sintetizirani su policiklički derivati gvanidina ukorporirani u oksanorbornenski kostur u obliku heksafluorfosfatnih soli. Ključni korak u pripravi svakog od spojeva jest
Diels-Alder reakcija 2-(furfurilamino)imidazolidinijevog heksafluorfosfata s različitim esterima acetilendikarboksilne kiseline u mikrovalnom reaktoru, dok je konačan produkt dobiven intramolekulskom aza-Michaelovom adicijom gvanidina na nastali supstituirani oksanorbornadien. Diels-Alderova reakcija je odabrana kao ekološki prihvatljiv pristup pripravi ciljnih molekula, dok je aza-Michaelova reakcija provedena propuštanjem sirovog produkta preko stupca SiO2. Tijekom istraživanja je utvrđeno kako smanjenje omjera reaktanata zahtijeva dulje vrijeme reakcije ili višu temperaturu što dovodi do bitnog povećanja udjela polimera u smjesi. Izolirani spojevi su okarakterizirani spektroskopskim tehnikama te je za svaki od pročišćenih produkata ispitana kokatalitička aktivnost u aldolnoj reakciji cikloheksanona i 4-klorbenzaldehida. Računskim putem je istražen utjecaj supstituenata na barijeru cikloadicije i mogući utjecaj supstituenta na cikloadiciju. Utvrđeno je kako većina supstituenata podižu barijeru cikloadicije u odnosu na metilni derivat što je u skladu s primijećenim nižim prinosima. DFT računima je okarakteriziran i utjecaj vodikove veze na promjene energija graničnih orbitala i na asinkronost reakcije.In this paper, polycyclic derivatives of guanidine incorporated into an oxanorbornene skeleton in the form of hexafluorophosphate salts were synthesized. The key step in the preparation of each of the compounds is the Diels-Alder reaction of
2-(furfurylamino)imidazolidine hexafluorophosphate with various esters of acetylenedicarboxylic acid in a microwave reactor, while the final product is obtained by intramolecular aza-Michael addition of guanidine to the resulting substituted oxanorbornadiene. The Diels-Alder reaction was chosen as an environmentally friendly approach to the preparation of target molecules, while the aza-Michael reaction was performed by passing the crude product through a SiO2 column. During the research, it was found that reducing the ratio of reactants requires a longer reaction time or a higher temperature, which leads to a significant increase in the proportion of polymers in the mixture. The isolated compounds were characterized by spectroscopic techniques, and the co-catalytic activity in the aldol reaction of cyclohexanone and 4-chlorobenzaldehyde was tested for each of the purified products. The influence of substituents on the cycloaddition barrier and the possible influence of substituents on cycloaddition were investigated computationally. Most of the substituents were found to raise the cycloaddition barrier compared to the methyl derivative, which is consistent with the observed lower yields.
The influence of the hydrogen bond on the changes in the energies of the frontier orbitals and on the asynchrony of the reaction was also characterized by DFT calculations