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Synthesis of biodiesel from waste alcoholic mixtures
No full textU ovom radu je opisan postupak dobivanja biodizela iz otpadnog alkohola fuselola i otpadnog suncokretovog ulja od prženja hrane. Cilj ovog završnog rada je ispitati utjecaj reakcijskih faktora na iskorištenje biodizela, odnosno modelirati reakcijski sustav primjenom faktorskog plana i metodologije odzivnih površina. Motivacija za provođenje ovog rada pojavila se kao sve veća potreba za pronalaskom obnovljivog goriva kao zamjene za fosilna goriva.
Direktiva o promicanju uporabe energije iz obnovljivih izvora (RED II/ EU 2018/2001) - zahtjeva od država članica da zajednički osiguravaju da udio energije iz obnovljivih izvora u ukupnoj konačnoj bruto potrošnji energije u Europskoj Uniji 2030. bude najmanje 32 %. Značajni reakcijski faktori za ovaj sustav su: temperatura, molarni omjer alkohola i ulja, maseni udio katalizatora KOH i broj okretaja miješala. Glavni rezultati upućuju na to da porast molarnog omjera reaktanata, masenog udjela katalizatora i broja okretaja miješala imaju pozitivan utjecaj na iskorištenje biodizela, dok porast temperature reakcije ima negativan utjecaj na iskorištenje biodizela. Najveće eksperimentalno iskorištenje od 56,3 mol. % dobiveno je pri uvjetima temperature od 60 °C, vremenu reakcije od 60 min, molarnom omjeru reaktanata od 12:1, masenom udjelu KOH od 3 % te broju okretaja miješala od
375 min^-1. Model je uspješno validiran za svih pet ispitanih slučajeva.This thesis describes biodiesel production from waste alcohol fuselol and waste sunflower oil for frying food. The goal of this final work is to examine the influence of reaction factors on the reaction conversion for biodiesel from waste oil and waste alcohol, that is, to model the reaction system using the response surface methodology. The motivation for writing and conducting this work emerged as the growing need to find a renewable fuel to replace fossil fuels. Directive on the promotion of the use of energy from renewable sources (RED II/ EU 2018/2001) - requires the Member States to jointly ensure that the share of energy from renewable sources in the total final gross energy consumption in the Union in 2030 is at least 32 %. Important reaction factors for this system are: temperature, molar ratio of alcohol and oil, mass fraction of KOH catalyst and number of revolutions of the mixer. The main results indicate that an increase in the molar ratio of reactants, the mass fraction of the catalyst and the number of revolutions of the mixer have a positive effect on the reaction conversion, while an increase in the reaction temperature has a negative effect on the reaction conversion. The highest experimental conversion of 56.3 mol. % was obtained at a temperature of 60 °C, reaction time of 60 min, a molar ratio of reactants of 12:1, a mass fraction of KOH of 3 %, and a stirring speed of 375 min^-1. The model was successfully validated for all five examined cases
Remediation of waters polluted with organics: the potential of UV-C/H2O2 i UV-C/S2O82- processes
No full textNapredovanjem tehnologije i sve većim zahtjevima tržišta, povećava se proizvodnja, a time i ispuštanje sve raznovrsnijih onečišćivala u okoliš, što zahtijeva njihovo nužno zbrinjavanje. Iako koncentracije neželjenih supstanci koje završavaju u otpadnim vodama mogu biti vrlo niske, gotovo zanemarive, itekako mogu predstavljati opasnost za okoliš u cjelini uslijed njihove trajne izloženosti. U ovom će se radu staviti naglasak na organske onečišćujuće tvari u vodenom mediju i načine na koje se iste mogu izolirati, ukloniti ili im smanjiti koncentraciju do dozvoljenih granica. Jedna od modernijih i učinkovitijih tehnika uklanjanja organskih onečišćujućih tvari iz medija upravo su napredni oksidacijski procesi, NOP (engl. advanced oxidation processes, AOPs). Radi se o procesima koji se koriste u slučajevima kada konvencionalne metode uklanjanja štetnih tvari ne pokazuju zadovoljavajuće rezultate.
U ovom će se radu ispitati potencijal UV-C/H2O2 i UV-C/S2O82- fotokemijskih procesa u kojima dolazi do razaranja onečišćivala na temelju kombinacije učinaka oksidansa i ultraljubičaste svjetlosti. Naime, dolazi do stvaranja visokoreaktivnih radikala koji su u mogućnosti djelomično ili u potpunosti razgraditi organske onečišćujuće tvari do jednostavnih produkata koji ne predstavljaju opasnost po okoliš.With the advancement of technology and increasing demands of the market, the production increases, so as the release of more diverse pollutants into the environment, which requires their necessary disposal. Although the concentrations of unwanted substances that end up in wastewater can be very low, almost negligible, they can represent a great danger to the environment as a whole, due to their permanent exposure. In this paper, emphasis will be placed on organic pollutants in the water medium and the ways in which they can be isolated, removed or their concentration can be reduced to permissible limits. One of the modern and effective techniques for removing organic pollutants from the media are advanced oxidation processes, AOPs. These processes are used in cases where conventional methods of removing harmful substances do not show satisfactory results. This paper will examine the potential of UV-C/H2O2 and UV-C/S2O82- photochemical processes in which the destruction of pollutants occurs based on a combination of oxidants and ultraviolet light effects.
The creation of highly reactive radicals, that are able to partially or completely break down organic pollutants into simple products that do not represent a danger to the environment, occurs
The influence of tray geometry on the efficiency of continuous biodiesel purification
No full textZbog sve veće eksploatacije nafte i potrebe za fosilnim gorivima, čije su količine u svijetu ograničene, primorani smo tražiti alternativne načine za dobivanje goriva i energije. S ciljem postizanja kružnog gospodarstva, očuvanja okoliša i iskorištavanja otpadnih tvari, dobivena je ideja za sintezu biodizela iz otpadnog jestivog ulja različitih tvornica, uz upotrebu ekološki prihvatljivih otapala i katalizatora. Istražen je utjecaj masenog omjera otapala i biodizela, intenziteta miješanja te geometrije plitica na učinkovitost kontinuiranog pročišćavanja biodizela u Karrovoj koloni s pulzacijskim pliticama. Biodizel je prethodno sintetiziran transesterifikacijom (maseni omjer katalizator:metanol:ulje = 1:40:100). Za karakterizaciju uzoraka korištene su sljedeće tehnike: plinska kromatografija i NMR spektroskopija. Uzorcima su također izmjerene gustoća, viskoznost, površinska napetost i međupovršinska energija, kontaktni kut i slobodna površinska energija. Na temelju izmjerenih fizikalnih i površinskih svojstava odabrano je ulje kao kontinuirana faza. Na učinkovitost ekstrakcije glicerola utječe geometrija plitica, maseni omjer otapala i biodizela te intenzitet miješanja.Due to the increasing depletion of oil and the growing demand for fossil fuels, the supply of which is limited, we are forced to look for alternative ways of generating fuel and energy. With the aim of achieving a circular economy, protecting the environment, and recycling waste materials, the idea of synthesizing biodiesel from waste cooking oil from various factories, using environmentally friendly solvents and catalysts, was developed. The study investigated the effects of solvent to biodiesel mass ratio, mixing intensity and tray geometry on the efficiency of continuous biodiesel purification in a pulsed tray column. The biodiesel was previously synthesized by transesterification (mass ratio of catalyst:methanol:oil = 1:40:100). The following techniques were used to characterize the samples: gas chromatography and NMR spectroscopy. In addition, the density, viscosity, surface tension, interfacial energy, contact angle, and free surface energy of the samples were measured. Based on the measured physical and surface properties, oil was selected as the continuous phase.
The efficiency of glycerol extraction was influenced by the geometry of the tray, solvent to biodiesel mass ratio and the intensity of mixing
Synthesis of iron oxide fibres by electrospinning
No full textPosljednjih godina se oksidi željeza intenzivno istražuju kao potencijalni fotokatalizatori i materijali za izradu anoda zbog dobre stabilnosti, netoksičnosti, niske cijene, dostupnosti te vrijednosti energijskog procijepa od ~2,1 eV. Međutim, mala električna provodnost te vrlo brza rekombinacija fotogeneriranih nosioca naboja (elektrona i šupljina) ograničavaju njihovu primjenu. Jedan od mogućih načina prevladavanja spomenutih nedostataka je sinteza oksida u formi nanostrukturiranih vlakana malog promjera, a velike specifične površine što utječe na njihova magnetska, optička i elektronska svojstva. U ovom radu su metodom elektroispredanja sintetizirana vlakna hematita te je provedena njihova kemijska, strukturna i morfološka, karakterizacija.In recent years, iron oxides have been intensively investigated as potential photocatalysts and materials for anode fabrication due to their good stability, non-toxicity, low cost, availability and energy gap value of ~2.1 eV. However, the low electrical conductivity and the very fast recombination of the photogenerated charge carriers (electrons and holes) limit their application. One of the ways to overcome the above shortcomings is the synthesis of oxides in the form of nanostructured fibres with small diameter and large specific surface area, which affect their magnetic, optical and electronic properties. In this work, the hematite fibres were synthesised by electrospinning method and their chemical, structural and morphological properties were characterised
Influence of sacrificial agent on stability of SnS2 photoanode
No full textCilj ovog rada bio je provesti fotoelektrokemijski proces dobivanja vodika te ispitati ponašanje SnS2 elektrode u vodenoj otopini 0.1 mol/dm3 NaCl uz dodatak čiste 1 i
3 mmol/dm^3 kofeinske kiseline (CA) ili kofeinske kiseline u kombinaciji s 1 mmol/dm^3 askorbinskom kiselinom (AA). Mjerenja su provedena za osvijetljene i neosvijetljene elektrode, a izvor svjetla bila je LED lampa. Provedena su i elektrokemijska ispitivanja na elektrodi od staklastog ugljika (GC elektroda) kako bi se utvrdila stabilnost CA i AA tijekom osvjetljenja te kako bi se ispitala njihova antioksidativna svojstva prema O2.- radikalu. Metode korištene u ovom radu za ispitivanje elektroda su ciklička voltametrija, linearna polarizacija, elektrokemijska impedancijska spektroskopija i kronoamperometrija. Rezultati dobiveni metodom linearne polarizacije i kronoamperometrije ukazuju da su struje za SnS2 elektrodu uz dodatak žrtvujućeg sredstva puno veće nego bez prisustva žrtvujućeg sredstva što potvrđuje dobru aktivnost CA i AA. Također, uz dodatak žrtvujućeg sredstva uočava se i porast stabilnosti elektrode. Ispitivanja provedena na GC elektrodi ukazuju da nije došlo do fotolize CA i AA prilikom izlaganja elektrode svjetlu te da AA ima veću djelotvornost kao žrtvujuće sredstvo, zbog niže vrijednosti potencijala strujnog vrha. Porastom koncentracije CA i dodatkom AA antioksidativna aktivnost prema O2.- radikalu raste. Impedancijska mjerenja pokazuju da su za osvijetljenu SnS2 elektrodu dobiveni puno manji otpori prijelazu naboja nego za neosvijetljenu što također potvrđuje dobru fotoaktivnost ove elektrode. Najveća stabilnost elektrode kao i najbolja fotoaktivnost dobivena je u otopini 1 mM CA i
1 mM AA što je potvrđeno metodom linearne polarizacije i elektrokemijske impedancijske spektroskopije.The aim of this work was to carry out a photoelectrochemical process of hydrogen production and to examine the behavior of the SnS2 electrode in an aqueous solution of 1 and
3 mmol/dm^3 caffeic acid (CA) in 0.1 mol/dm3 NaCl in the presence or absence of
1 mmol/dm^3 ascorbic acid (AA). Measurements were performed for illuminated and
non-illuminated electrodes, and the light source was an LED lamp. Electrochemical experiments were also carried out on a glassy carbon electrode (GC electrode) in order to determine the stability of CA and AA during illumination and to test the antioxidant properties of CA and AA against the O2.- radical. The methods used in this work for testing electrodes are cyclic voltammetry, linear polarization, electrochemical impedance spectroscopy and chronoamperometry. The results obtained using linear polarization and chronoamperometry methods indicate that the currents for the SnS2 electrode with the addition of sacrificial agent are much higher than without the presence of sacrificial agent, confirming the good activity of CA and AA. Also, the addition of sacrificial agents results in an increase in electrode stability. Investigations conducted on the GC electrode suggest that there was no photolysis of CA and AA when exposed to light, and AA is more effective as a sacrificial agent due to its lower potential value of the current peak. The increase in CA concentration and the addition of AA lead to an increase in antioxidant activity towards O2.- radicals. Impedance measurements show that illuminated SnS2 electrodes have much lower charge transfer resistances than non-illuminated ones, further confirming the good photoactivity of this electrode. The highest electrode stability and best photoactivity were achieved in a solution containing 1 mM CA and 1 mM AA, as confirmed by linear polarization and electrochemical impedance spectroscopy
Synthesis, characterization and development of pharmaceutical biodegradation processes
No full textFarmaceutici su ključni u održavanju i poboljšanju ljudskog zdravlja, pružajući učinkovita sredstva za prevenciju, liječenje i ublažavanje simptoma mnogih bolesti. Međutim, rastući problem antimikrobne rezistencije predstavlja ozbiljan izazov za učinkovitost mnogih lijekova, posebno antibiotika. Zbog prekomjerne upotrebe i zlouporabe antimikrobnih sredstava, mnogi patogeni su razvili otpornost, što zahtijeva razvoj novih, inovativnih lijekova i terapija kako bi se uspješno borilo protiv otpornih infekcija i očuvalo zdravlje populacije. Cilj rada je provesti termička ispitivanja na novim stilbenskim sustavima koji su pripremljeni Wittigovom reakcijom u svrhu dobivanja novih struktura. Produkti termičke reakcije su indanski i indenski derivati. Dobivenim produktima reakcije ispitano je potencijalno antimikrobno djelovanje.Pharmacists are essential in maintaining and improving human health, providing effective means to prevent, treat and relieve the symptoms of many diseases. However, the growing problem of antimicrobial resistance poses a serious challenge to the effectiveness of many medicines, especially antibiotics. Due to the excessive use and misuse of antimicrobials, many pathogens have developed resistance, which requires the development of new, innovative medicines and treatments to successfully combat resistant infections and preserve population health. The aim of the paper is to perform thermal tests on new styling systems prepared by Wittig's reaction in order to obtain new structures. Thermal reaction products are indanese and indene derivatives. The resulting reaction products tested the potential antimicrobial activity
Drug release modification with macrocyclic receptors
No full textDasatinib je antikancerogeni lijek koji se koristi u liječenju kronične mijeloične i akutne limfoblastične leukemije. Zbog svoje slabe topljivosti u vodenom mediju ima ograničenu bioraspoloživost. S ciljem povećanja njegove topljivosti pripravljeni su inkluzijski kompleksi s β-ciklodekstrinom mljevenjem u planetarnom kugličnom mlinu. Mehanokemijska aktivacija omogućuje pripravu bez primjene otapala poštujući načela zelene kemije, a istovremeno poboljšavaju topljivost i bioraspoloživost dasatiniba. Pripravljeni uzorci karakterizirani su diferencijalnom pretražnom kalorimetrijom, rendgenskom difrakcijom na praškastom uzorku, infracrvenom spektroskopijom s Fourierovim transformacijama i nuklearnom magnetskom rezonancijom. Detaljna analiza potvrdila je mehanokemijsku sintezu inkluzijskog kompleksa dasatiniba. Inkluzijski kompleksi i granulati pomoćnih tvari korišteni su u pripravi tableta. Dobivene tablete karakterizirane su pomoću standardiziranih farmaceutskih testova u skladu s preporukama Europske farmakopeje. Rezultati testiranja pokazali su poboljšanje topljivosti i oslobađanja djelatne tvari u usporedbi s čistim dasatinibom, što ukazuje na potencijalno poboljšanje bioraspoloživosti i terapijske učinkovitosti lijeka. Rezultati matematičkog modeliranja pokazuju profil oslobađanja koji slijedi model nultog reda. Ovaj rad jasno ukazuje na potencijal inkluzijskih kompleksa s β-ciklodekstrinom za poboljšanje bioraspoloživosti i efikasnosti dasatiniba, što može pridonijeti boljem ishodu liječenja leukemije.Dasatinib is an anticancer drug used in the treatment of chronic myeloid and acute lymphoblastic leukemia. Due to its poor solubility in aqueous medium, it has limited bioavailability. To increase its solubility, inclusion complexes with β-cyclodextrin were prepared by milling in a planetary ball mill. Mechanochemical activation allows for preparation without the use of solvents, following the principles of green chemistry while simultaneously improving the solubility and bioavailability of dasatinib. Prepared samples were characterized by differential scanning calorimetry, X-ray diffraction, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance. Detailed analysis confirmed mechanochemical synthesis of the inclusion complex of dasatinib. The iclusion complexes and granulates of excipients were used in the preparation of tablets. Obtained tablets were characterized using standardized pharmaceutical tests in accordance with the European Pharmacopoeia recommendations. Testing results showed an improvement in solubility and drug release compared to pure dasatinib, indicating a potential enhancement in bioavailability and therapeutic efficacy of drug product. Results of mathematical modelling demonstrated a release profile following a zero-order model. This thesis clearly indicates the potential of β-cyclodextrin inclusion complexes to enhance the bioavailability and efficiency of dasatinib, which may contribute to better treatment outcomes for leukemia
Natural deep eutectic solvent preparation and characterization
No full textNiskotemperaturna eutektička otapala pojavila su se prije sedamnaest godina u području zelene kemije te se intenzivno proučavaju kao ekološki prihvatljiva zamjena za štetna organska otapala. Smatraju se posebnom vrstom zelenih otapala zbog visoke topljivosti, niskih troškova te jednostavne metode pripreme i sinteze. Nastaju kombinacijom dvaju spoja: akceptora vodikove veze (HBA) i donora vodikove veze (HBD). Struktura i fizikalno-kemijska svojstva tih otapala mogu se dizajnirati za specifičnu primjenu. U ovom radu su pripremljena otapala koja se temelje na kolin kloridu i prirodnim organskim kiselinama. Provedena je fizikalno-kemijska karakterizacija pripremljenih DES-ova. Izmjerene su vrijednosti gustoće, viskoznosti te kiselost. Pratio se utjecaj promjene komponente koja je donor vodikove veze te dodatak masenog udjela vode na fizikalno-kemijska svojstava DESova. FTIR analizom je potvrđen nastanak strukture DES-a. Svi pripravljeni DES-ovi su kapljevine, izrazito kisele i visoke viskoznosti te se ponašaju kao Newtonovi fluidi. Gustoća im se kreće u rasponu od 1,18 do 1,33 g/cm^3. FTIR analizom dobiveni su pikovi karakteristični za DES-ove.In the field of green chemistry, deep eutectic solvents first emerged seventeen years ago, and researchers are actively studying them as an environmentally friendly replacement for hazardous organic solvents.They are considered as a special type of green solvents due to their high solubility, low costs and simple methods of preparation and synthesis. They are formed by the combination of two compounds: a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD). The structure and physicochemical properties of these solvents can be designed for a specific application. In this work, solvents were prepared based on choline chloride and natural organic acids. Physicochemical characterization was made for prepared DESs. Density, viscosity and acidity values were measured. The influence of the hydrogen bond donor component and adding a mass proportion of water on the physicochemical properties of DESs were investigated. FTIR research confirmed the formation of the DES structure. All DES are liquids, very acidic, highly viscous, and behave like Newtonian fluids. Their density changes between 1.18 and 1.33 g/cm^3. The FTIR investigation identified DES-specific peaks
Modification of commercial nanofiltration membranes to improve their performances
No full textTlačni membranski proces nanofiltracije (NF) koristi se za obradu vode za piće i otpadnih voda. Kako obično ne pokazuju visoke faktore separacije prema nenabijenim molekulama male molekulske mase, cilj ovog istraživanja bio je poboljšati učinkovitost triju komercijalnih NF membrana (NF90, TS80, DK) pri uklanjanju N-nitrozodimetilamina (NDMA) modifikacijom pomoću 4-nitrobenzensulfonil klorida (NBS) kao molekulskog blokatora. Analiziran je sastav struja prije i nakon nanofiltracijske obrade te je praćena permeabilnost vode, odnosno protok permeata. Također su ispitane i promjene površine membrana, tj. njihov aktivni sloj nakon postupka modifikacije. Rezultati pokazuju da je modifikacijom komercijalne DK membrane NBS-om povećan faktor separacije NDMA molekule s 26,0 % na 45,2 % uz zadržavanje
75,93 % početne permeabilnosti čiste vode, što je daleko bolje od preostalih membrana čija se permeabilnost smanjila za 54,84 i 61,29 %. NF90 membrana pokazuje povećanje faktora separacije NDMA molekule s 20,9 na 47,1 %, što je 4,03 % bolje od DK membrane te pokazuje i najviši faktor separacije soli. Ni jedna od ispitivanih membrana nije pokazala dovoljno visok faktor separacije NDMA molekule da bi zadovoljila regulativama zadane granice koncentracija u vodi za piće.Pressure-driven nanofiltration (NF) processes are used in drinking water and wastewater treatment. Since they often don't show high rejection rates of uncharged particles of low molecular weight, the goal of this research was to enhance the N-nitrosodimethylamine (NDMA) rejection efficiency for three commercially available NF membranes (NF90, TS80, DK) via modification using 4-nitrobenzenesulfonyl chloride (NBS) as a molecular plug. Stream compositions were analysed after and prior to the nanofiltration treatment. Water permeability, or rather permeate flow, was measured and changes in the membrane surface, i.e. their active layers post modification were analysed as well. Results show that modifying the commercially available DK membrane increased the rejection rate of NDMA molecule from 20,0 % to 45,2 % while retaining 75,93 % of its original pure water permeability which is miles above the other membranes whose permeability dropped by 54,84 and 61,29 %. The NF90 membrane shows an increase of NDMA molecule rejection rates from 20,9 % to 47,1 % which is 4,03 % higher than the DK membrane, as well as showing the best salt rejection rates. None of the membranes tested here reached NDMA molecule rejection rates high enough to meet the allowed concentrations in drinking water set by regulatory bodies
Ecotoxicological, physicochemical and microbiological characterization of raw water from scrubbers for gas purification
No full textU ovom radu analizirane su fizikalno-kemijske, mikrobiološke i ekotoksikološke karakteristike dobivenih uzoraka nakon elektrokemijskog procesa(elektrokoagulacije) pročišćavanja. Pročišćavane su zauljene otpadne vode mineralnog podrijetla koje se dobivaju postupkom pročišćavanja dimnih plinova iz procesa uplinjavanja mulja s uređaja za pročišćavanje otpadnih voda. Ispitivane fizikalno-kemijske karakteristike su pH vrijednost, količina otopljenog kisika i električna vodljivost uzoraka na pripadnim elektrodama te analiza ukupne količine ugljika. Mikrobiološka karakterizacija se radila na hranjivom i malt agaru, a ekotoksikološka karakterizacija na morskim bakterijama Vibrio fischeri. Rezultati navedenog istraživanja ukazuju jeli potrebno dodatno pročistiti otpadnu vodu nakon pročišćavanja elektrokemijskim procesom elektrokoagulacije s obzirom na granične vrijednosti prema Pravilniku o graničnim vrijednostima emisija otpadnih voda.In this work, the physico-chemical, microbiological and ecotoxicological characteristics of the samples obtained after the electrochemical process (electrocoagulation) of purification were analyzed. Oily wastewater of mineral origin, which is obtained by the process of purifying flue gases from the process of gasification of sludge from wastewater treatment plants, was purified. The tested physical and chemical characteristics are the pH-value, the amount of dissolved oxygen and the electrical conductivity of the samples on the corresponding electrodes, as well as the analysis of the total amount of carbon. Microbiological characterization was performed on nutrient and malt agar, and ecotoxicological characterization on bacteria Vibrio fischeri. The results of the mentioned research indicate whether it is necessary to additionally purify the waste water after purification by the electrochemical process of electrocoagulation. That is, whether the results of the determined characteristics were obtained in the limit values according to the Rulebook on the limit values of waste water emissions