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Hydrogen peroxide can be produced electrochemically by selective oxygen reduction reaction or selective water oxidation reaction in various electrolytes. A very promising, sustainable, and efficient method to produce hydrogen peroxide is the so-called electrochemical “lab-on-a-chip” technology, where microfluidic electrochemical flow cells can be used. The main advantage of such a system is “on demand” and “on site” production. If these systems are to be commercialized, suitable electrocatalysts (anode and cathode), sensors, and a device design must be developed and interconnected. Such technology could then eventually be deployed in an industrial environment with internal/external numbering-up approach.

Hepatociti so visoko specializirane polarizirane jetrne celice, v katerih se vrši večina za jetra specifičnih funkcij. Izolacija primarnih hepatocitov je skupek stresnih dejavnikov, med katerimi izstopa encimska razgradnja medceličnih stikov. Zaradi stresa ob izolaciji se v primarnih podganjih hepatocitih pojavi reverzibilna stresna prilagoditev, imenovana predapoptotski celični odziv na stres (PACOS), ki preko inaktivacije kaspaze 9 onemogoči proženje apoptoze po mitohondrijski poti ter nastopi takoj po izolaciji in izzveni do 6. dne v kulturi. Namen našega dela je bil proučiti PACOS ter njegov vpliv na delovanje hepatocitov in na odziv hepatocitov na dodatni stresni dejavnik (hipoksija in reoksigenacija). Zanimalo nas je tudi, ali so pri proučevanju PACOS sveže tkivne rezine jeter kontrola celičnim kulturam primarnih hepatocitov. V doktorskem delu smo pokazali, da primarni hepatociti v kulturi preživijo ter ohranijo nivo presnovne aktivnosti in sposobnost tvorbe sečnine. Potrdili smo stalno pojavnost PACOS v izoliranih primarnih hepatocitih. Raziskali smo proženje apoptoze v podganjih primarnih hepatocitih in dokazali, da v normalnih pogojih poteče po mitohondrijski poti. Sveže jetrne rezine so glede PACOS lahko kontrola primarnim hepatocitom, saj je v rezinah kaspazo 9 moč učinkovito aktivirati. Prvič smo pokazali, da sta posledici stresa pri izolaciji hepatocitov dva reverzibilna odziva na stres: indukcija endogenega antioksidativnega odziva in PACOS. Oba sproži povečano nastajanje ROS, ki tako omogoči preživetje in normalno delovanje celic. Poleg tega smo pokazali, da so na stres prilagojeni primarni hepatociti manj občutljivi na proženje apoptoze po hipoksiji/reoksigenaciji kot hepatociti pozne kulture, pri katerih sta PACOS in antioksidativni odziv izzvenela. Primarni hepatociti so relevanten in z nekaterimi omejitvami ustrezen model za temeljno proučevanje detoksikacije, metabolizma in potencialnih terapevtikov. Na podlagi rezultatov naše raziskave poudarjamo, da se na stres prilagojeni hepatociti na dodatne stresne dejavnike odzivajo drugače kot hepatociti in vitro ter in vivo, v katerih stresnih odzivov ni. Razumevanje mehanizmov ROS in odzivov na stres v primarnih hepatocitih je ključnega pomena za načrtovanje raziskav, za interpretacijo rezultatov, za prenos izsledkov na razmere in vivo in v končni fazi za razumevanje fiziologije in patofiziologije jeter ter oblikovanje posegov za preprečevanje in zdravljenje jetrne patologije. Hepatocytes are highly specialized polarized liver cells in which most liver-specific functions are performed. Isolation of primary hepatocytes is a set of stressors, among which the enzymatic degradation of intercellular junctions stands out. Due to stress upon isolation, a reversible stress adaptation called pre-apoptotic cell stress response (PACOS) occurs in primary rat hepatocytes and through inactivation of caspase-9 prevents apoptosis triggering through the intrinsic pathway. PACOS is present immediately after isolation and dissipates by day 6 in culture. The aim of our study was to examine/investigate PACOS, its impact on hepatocyte function, hepatocyte response to additional stressors (hypoxia and reoxygenation), and whether precision-cut liver slices can be used as a control to primary hepatocyte cell cultures in the PACOS study. In our work we demonstrated that primary hepatocytes survive in culture and maintain the level of metabolic activity and the ability of urea production. We confirmed the constant occurrence of PACOS in isolated primary hepatocytes. We investigated the induction of apoptosis in primary hepatocytes and demonstrated that it is normally activated through the intrinsic pathway. Precision-cut liver slices can serve as a control to primary hepatocytes with respect to PACOS, as caspase-9 can be efficiently activated in the slices. For the first time, we have shown that the consequences of stress in hepatocyte isolation are two reversible responses to stress: induction of an endogenous antioxidant response and PACOS. Both are triggered by increased ROS, which mediate cell survival and normal function. In addition, we showed that stress-adapted primary hepatocytes are less susceptible to triggering apoptosis after hypoxia/reoxygenation than hepatocytes in which PACOS and antioxidant response are no longer present. Primary hepatocytes are a relevant and, with some limitations, appropriate model to study detoxification, metabolism, and potential therapeutics. Based on the results of our study, we emphasize that stress-adapted hepatocytes respond differently to additional stressors than hepatocytes in vitro and in vivo, in which the stress responses are not induced. Understanding the mechanisms of ROS and stress responses in primary hepatocytes is crucial for planning research, interpreting the results, applying them in vivo and, ultimately, for understanding liver physiology, pathophysiology, and devising interventions for prevention and treatment of liver pathology.

V magistrskem delu sem po modificiranih postopkih sintetiziral enoatomske elektrokatalizatorje kovin prehoda (SAC) na osnovi niklja, kobalta, mangana in železa na reduciranem grafen oksidu (rGO), ki naj bi izkazovali selektivnost za elektrosintezo vodikovega perksida. Vse sintetizirane SAC materiale na rGO sem ustrezno okarakteriziral s sledečimi metodami: vrstični elektronski mikroskop (SEM), energijsko disperzijska rentgenska spektroskopija (EDS), rentgenska fotoelektronska spektroskopija (XPS), ramanska spektroskopija in BET analiza specifične površine. Prav tako sem pri karakterizaciji elektrokatalizatorjev uporabil elektrokemijske metode, kot so: ciklična voltametrija (CV) v kombinaciji z rotirajočo disk elektrodo (RDE) in rotirajočo disk elektrodo z obročem (RRDE). Proučil in primerjal sem njihovo morfologijo, kemijsko strukturo in elektrokemijske lastnosti. Rezultati so pokazali, da je najustreznejši elektrokatalizator za elektrosintezo vodikovega peroksida, Ni na rGO v alkalnem elektrolitu. Rezultati raziskave so uporabni za nadaljnje raziskave, razvoj in optimizacijo elektrokatalizatorjev za selektivno in učinkovito elektrosintezo vodikovega peroksida. In the master's thesis, I synthesized transition metal single atom electrocatalysts (SAC) based on nickel, cobalt, manganese and iron on reduced graphene oxide (rGO) using modified procedures, which should show selectivity for the electrosynthesis of hydrogen peroxide. All synthesized SAC materials on rGO were properly characterized by the following methods: scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), raman spectroscopy and BET specific surface area analysis. To investigate their electrochemical performance additional characterization methods such as cyclic voltammetry (CV), chronoamperometry (CA) with rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) were used. The morphology, chemical structure and electrochemical properties were compared. The results showed that the most suitable electrocatalyst for the electrosynthesis of hydrogen peroxide is Ni on rGO in an alkaline electrolyte. The research results are useful for further research, development and optimization of electrocatalysts for the selective and efficient electrosynthesis of hydrogen peroxide.

V obdobju od leta 2018 do leta 2021 smo izvedli poskus, pri katerem smo preučevali učinkovitost vodikovega peroksida za zdravljenje in preprečevanje širjenja bolezni lesa vinske trte (BLVT). Vodikov peroksid je anorganska spojina, ki je prisotna v rastlinah kot signalna molekula oziroma vpliva na aktivacijo drugih organskih molekul, ki sprožijo obrambne mehanizme v rastlini. Opazovanje in tretiranje trt je potekalo v vinogradu v bližini Komna na Krasu. Vinograd je obsegal 279 trt sorte 'Refošk'. Uspešnost tretiranja smo opazovali v obdobju od 2018 do 2021. Opazovanje je potekalo tako, da smo vsako trto pregledali, ji določili zdravstveno stanje ter informacijo o zdravstvenem stanju vpisali v terenski zvezek. V okužene rastline smo v glavo debla zavrtali do globine 5-6 cm. V izvrtino smo vbrizgali 5 ml 10 % vodikovega peroksida in izvrtino zaščitili s folijo za živila. Rastline so bile v rastni sezoni tretirane z vodikovim peroksidom le enkrat letno. Po štirih letih opazovanja in dela smo opazili, da smo z učinkovino preprečili propad 58,2 % okuženih trt. To nakazuje da je učinkovina delno preprečila propad trt v izbranem vinogradu. V letu 2020 so propadle štiri tretirane trte, v letu 2021 pa 33 tretiranih trt, ki smo jih nadomestili z novimi. Kontrolnega poskusa, kjer bi bile vključene netretirane okužene trte in tretirane zdrave trte, nismo izvajali. Vzrok za propad pripisujem močnim okužbam s patogeni in suši v letu 2021. During the period from 2018 to 2021, we participated in the conduct of an experiment to study the effectiveness of hydrogen peroxide in treating and preventing the spread of grapevine diseases (BLVT). Hydrogen peroxide is an inorganic compound that occurs in plants as a wear molecule or affects other organic molecules that trigger the plant's immune system. The observation and treatment of the vines took place in a vineyard near Komen in the Karst. The vineyard included 279 vines of ʽRefoškʼ variety and the success of the treatment was checked in the following year. The inspection was carried out in such a way that we examined each vine and determined its state of health, which was recorded in the field book. The infected plants were bored to a depth of 5-6 cm in the stem area. 10% hydrogen peroxide was injected into the drilled hole, and the resulting hole was protected with grocery. Plants were treated only once during the growing season. After four years of observation and work, we noticed that we successfully cured 58,2 % of diseased vines with active ingredient. Suggesting the effectiveness of the preparation in preventing the spread of infection throughout the vineyard. This indicates that the active substance prevented the partially decline of the vines in the selected vineyard. Four treated vines failed in 2020, and 30 treated vines in 2021, then we replaced them with new ones. We did not perform a control experiment, where untreated infected vines and treated healthy vines were included. I attribute the cause of the collapse to strong infections with pathogens, the drought in 2021.

We have developed a cheap, green, mild and environmentally friendly method for the selective cleavage of carbon–carbon double bonds with a 30% aqueous solution of hydrogen peroxide as the oxidant and vanadium(V) oxide as the catalyst. The selectivity of the oxidative cleavage of cinnamic acid derivatives 1 depends on the substituents and the solvent used (DME – MeOCH$_2$CH$_2$OMe, TFE – 2,2,2-trifluoroethanol or MeCN). In DME, p-hydroxy derivatives were selectively converted to benzaldehyde derivatives 2, in TFE, oxidative cleavage led to the formation of benzoquinone derivatives 4, while in MeCN, cinnamic acid derivatives were selectively converted to benzoic acid derivatives 3. Ferulic acid 1a was quantitatively and selectively converted to vanillin 2a in a 91% isolated yield on a gram scale. Dimeric difurandione 1a’ was isolated as an intermediate, which was confirmed by in situ ATR-IR spectroscopy, while the formation of diols or epoxides was not observed. The analogous styrene derivative, 4-vinylguaiacol 1e was also selectively converted to either vanillin 2a or 2-methoxyquinone 4a in a high yield. The green metric for the conversion of ferulic acid to vanillin by different methods was calculated and compared to our method, and showed that our method has better environmental parameters.

Velika proizvodnja i uporaba nanočestica srebra (AgNPs) može dovesti do ispuštanja istih u morski okoliš što posljedično može dovesti do smrtnosti različitih vrsta morskih organizama. Dosadašnja istraživanja dokazala su toksičnost AgNPs na morskim beskralješnjacima i fitoplanktonu, no nedostaju istraživanja učinka AgNPs na morskim makroalgama. Morske makroalge vrlo su važan dio morskog ekosustava. One obogaćuju morski okoliš kisikom, važna su hrana herbivornim vrstama organizama te pružaju stanište i skrovište različitim vrstama kralješnjaka i beskralješnjaka. Cilj rada bio je ispitati kako različite veličine nanočestica srebra utječu na toksičnost kod crvene morske makroalge Laurencia obtusa. Toksičnost AgNPs istraživana je pomoću biomarkera lipidne peroksidacije i sadržaja vodikovog peroksida koji ukazuju na oksidacijski stres. Talusi morske makroalge L. obtusa bili su izloženi AgNPs veličina 20 i 60 nm u koncentracijama od 1, 10 i 100 μg/mL tijekom 24 sata. Rezultati testa lipidne peroksidacije pokazali su najveću toksičnost Ag60 u koncentraciji od 100 μg/mL, a Ag20 nisu značajno utjecale na lipidnu peroksidaciju u L. obtusa. Rezultati sadržaja vodikovog peroksida također su ukazali na veću toksičnost Ag60, ali pri najnižoj ispitanoj koncentraciji. U oba testa AgNPs pokazale su veću toksičnost od Ag+ iona. Vidljivo je da u istraživanju s crvenim makroalgama veće AgNPs imaju veći toksični utjecaj. Potrebno je provesti daljnja istraživanja kako bi s većom sigurnošću bio određen utjecaj AgNPs na morske makroalge. Large- scale production and use of silver nanoparticles (AgNPs) may lead to their release into the marine environment, which can consequently lead to the death of various marine organisms. Previous research has proven the toxicity of AgNPs to marine invertebrates and phytoplankton, but there are scarcely any data available on their effect on marine macroalgae. Marine macroalgae are a very important part of the marine ecosystem as they enrich the marine environment with oxygen, are important food for herbivorous species of organisms and provide a habitat and hiding place for different species of vertebrates and invertebrates. The aim of this work was to examine how different particle sizes modulates the toxicity of silver nanoparticles to the red marine macroalgae Laurencia obtusa. The toxicity of AgNPs was investigated using lipid peroxidation and hydrogen peroxide content as indicators of negative stress. The thalli of L. obtusa were exposed to AgNPs, of sizes of 20 and 60 nm, in concentrations of 1, 10 and 100 μg/mL for a period of 24 hours. The results of the lipid peroxidation test showed the highest toxicity from Ag60 at a concentration of 100 μg/mL, while Ag20 did not significantly affect toxicity towards L. obtusa. Hydrogen peroxide content also indicated greater toxicity of Ag60, but at the lowest tested concentration. In both tests, AgNPs typically showed greater lipid peroxidation and hydrogen peroxide generation than Ag+ ions. Furthermore, larger AgNPs were found to have a greater impact on toxicity. Ultimately, it is necessary to carry out further research to determine with greater certainty the impact of AgNPs on marine macroalgae using a wider range of endpoints.

Enzimi su građeni od proteina, jedne od četiri glavnih skupina biomolekula. Ljudski organizam bez njih ne bi mogao funkcionirati jer bi se neke metaboličke reakcije odvijale presporo pa su zato oni tu da ubrzaju te reakcije. Ubrzavanje tih reakcija se temelji na vezanju supstrata u aktivno mjesto, a to vezanje može biti na principu ključ-brava kada supstrat idealno pristaje u aktivno mjesto enzima ili može biti izazvano pristajanje kada se enzim prilagodi na supstrat. U početku rada će biti opisane kemijske reakcije prvog, drugog i nultog reda radi boljeg razumijevanja enzimskih reakcija. Također će biti prikazan cijeli izvod formule za računanje brzine enzimske reakcije, koja se do određene koncentracije supstrata povećava, a nakon toga ostaje stalna kada je sav enzim zasićen supstratom. Svaki enzim sastoji se od aktivnog mjesta u kojem ima afinitetno mjesto koje sudjeluje u vezanju supstrata te katalitičko mjesto koje sudjeluje u provedbi reakcije. Enzimi različito djeluju, pri različitim uvjetima temperature, pH i u prisustvu inhibitora. Na kraju rada provedeno je ispitivanje aktivnosti enzima katalaze pri određenim uvjetima pH i temperature. Katalaza provodi reakciju razgradnje vodikovog peroksida na vodu i kisik.

Sodobni trendi pri strojnem pranju perila gredo v smer pranja z majhnimi količinami vode in pri nizkih temperaturah, da je poraba električne energije čim manjša. Tekoči detergenti, ki se vse pogosteje uporabljajo pri pranju, ne zagotavljajo higienske neoporečnosti, zato je potreba po razvoju detergenta, ki bi zagotavljal tako estetsko kot tudi higiensko čistočo, zelo velika. Vodikov peroksid kot okolju prijazna spojina lahko kot dodatek v tekočem detergentu poskrbi za higiensko, surfaktanti pa za estetsko čistočo, medtem ko stabilizatorji zagotavljajo čim večjo stabilnost vodikovega peroksida v takšnih formulacijah. V diplomskem delu sem raziskovala vpliv različnih kombinacij surfaktantov in stabilizatorjev na stabilnost 12 % vodikovega peroksida, spremembe pH raztopin ter kapaciteto in stabilnost pene, ki jo tvorijo vzorci. Koncentracijo vodikovega peroksida v študiranih formulacijah sem določevala z avtomatsko potenciometrično titracijo z natrijevim tiosulfatom v časovnem razponu osmih mesecev. Dobro stabilnost so pokazale vse formulacije vodikovega peroksida s 5 % vsebnostjo surfaktantov, stabilizirane s kombinacijo citronske in dipikolinske kisline kot ekološko sprejemljivima stabilizatorjema. Modern trends in machine washing clothes are moving toward washing with small amounts of water and at low temperatures to minimize power consumption. Liquid detergents, which are increasingly used for washing, do not guarantee hygienic integrity, thus there is a greater need to develop a detergent that ensures both aesthetic and hygienic cleanliness. Hydrogen peroxide as an environmentally friendly compound can be used as an additive in liquid detergents to provide hygienic, surfactants for aesthetic cleanliness, while stabilizers ensure maximum stability of hydrogen peroxide in such formulations. In this paper, I investigated the influence of different combinations of surfactants and stabilizers on the stability of 12 % hydrogen peroxide, on changes in the pH of the solutions, and on the capacity and stability of the foam formed by the samples. The hydrogen peroxide concentration in the formulations studied was determined by automatic potentiometric titration with sodium thiosulfate over a period of eight months. Good stability was shown by all hydrogen peroxide formulations with 5 % surfactant content, stabilized with a combination of citric and dipicolinic acids as ecologically compatible stabilizers.

Vodikov peroksid je preprosta molekula, ki se uvršča med okolju prijazne spojine, saj pri razpadu nastaneta kisik in voda. Uporablja se za čiščenje odpadne in pitne vode, za sterilizacijo embalaže v prehrambni industriji, za dezinfekcijo v zdravstvu in farmaciji, kot belilno sredstvo, za razgradnjo industrijskih odpadnih snovi, kot gorivo, za sintezo farmacevtskih izdelkov in v kozmetiki. Zaradi raznolike uporabe ga pripravljajo v zelo različnih formulacijah. V prisotnosti nečistoč, kot so kovinski ioni in delci v zraku, pri povišani temperaturi, pri višjih pH vrednostih in izpostavljenosti sončni svetlobi, pride do katalitičnega eksotermnega razpada te molekule. Tudi voda deluje kot nečistoča, zato vodne raztopine z nižjo koncentracijo H2O2 hitreje razpadajo, kar se kaže kot glavna pomanjkljivost, da bi vodikov peroksid zadostil zahtevam za široko komercialno uporabo. Za izboljšanje stabilnosti H2O2 dodajajo različne stabilizatorje, največkrat stanate in fosfate, med temi pa sta v zadnjem času komercialno najpogosteje uporabljena ATMP in HEDP. V magistrskem delu sem spremljala stabilnost vodikovega peroksida različnih koncentracij v različnih medijih in raziskovala možnosti stabiliziranja z namenom ohraniti njegovo stabilnost v širokem koncentracijskem območju in v različnih topilih. Pripravila sem razredčene raztopine komercialnega vodikovega peroksida v zmeseh različnih alkoholov z vodo. Njihovo stabilnost sem spremljala pri sobni temperaturi, 40 in 60 °C tako, da sem spremljala koncentracijo vodikovega peroksida z jodometrično titracijo. Pri raziskavah vpliva stabilizatorjev na stabilnost vodikovega peroksida sem uporabljala 40 ut.% nestabilizirano surovo vodno raztopino vodikovega peroksida in iz nje pripravila razredčene raztopine z dodatki različnih organskih kislin kot stabilizatorjev. Njihov stabilizacijski učinek sem spremljala s t. i. stresnim testom stabilnosti raztopin vodikovega peroksida pri temperaturi 96 °C 16 ur s prej omenjeno volumetrično metodo. Raziskovala sem tudi možnost spektrofotometričnega določevanja tvorbe perokso kompleksov vodikovega peroksida z metiltrioksorenijem(VII) in tvorbe kompleksov med železovimi in tiocianatnimi ioni v prisotnosti vodikovega peroksida. Hydrogen peroxide is a simple molecule that is classified as an environmentally friendly compound because it decomposes to produce oxygen and water. It is used for wastewater and drinking water treatment, sterilization of packaging in the food industry, disinfection in health care and pharmacy, bleaching, decomposition of industrial waste, as a fuel and for the synthesis of drugs and cosmetics. Due to its wide range of applications, it is produced in a variety of formulations. In the presence of impurities such as metal ions and particles in the air, at elevated temperatures, higher pH values and in the presence of sunlight, catalytic exothermic decomposition of this molecule occurs. Water also acts as an impurity, so aqueous solutions with a lower H2O2 concentration decompose more rapidly, which proves to be a major disadvantage for hydrogen peroxide if it is to meet the requirements for widespread commercial use. To improve the stability of H2O2, various stabilizers are added, usually stanates and phosphates, of which ATMP and HEDP are the most commonly used. In my Master's thesis, I studied the stability of hydrogen peroxide at various concentrations in different media and explored stabilization over a wide range of concentrations in different solvents. Dilute solutions of commercial hydrogen peroxide in mixtures of various alcohols with water were prepared. Their stability was monitored at room temperature, 40 and 60 °C by monitoring the hydrogen peroxide concentration by iodometric titration. In studies on the effect of stabilizers on the stability of hydrogen peroxide, 40 wt% unstabilized aqueous solution of hydrogen peroxide was used and dilute solutions were prepared from it with the addition of various organic acids as stabilizers. Their stabilizing effect was monitored by the stress test for the stability of hydrogen peroxide solutions at 96 °C for 16 hours using the above volumetric method. I also investigated the possibility of spectrophotometric determination of the formation of peroxocomplexes of hydrogen peroxide with methyltrioxorenium(VII) and the formation of iron complexes by thiocyanate ions in the presence of hydrogen peroxide.

Vodikov peroksid je kemikalija, po kateri je v svetu vedno več povpraševanja. Zaradi tega se vedno več raziskovanja usmerja v neposredno sintezo H2O2 z namenom zamenjave antrakinonskega procesa. Del diplomskega dela se posveča teoretičnemu ozadju mehanizmov adsorpcije ter reakcij na katalizatorjih. Nato smo za raziskovanje neposredne sinteze za polšaržni sistem razvili matematični model, ki upošteva omejitve masnega prenosa tekoče – trdno. Za reakcijske hitrosti so bile uporabljene hitrosti, ki temeljijo na mehanizmih Languir-Hinshelwood in Eley-Rideal ter z njimi ustrezne konstante, ki so bile pridobljene v delih prejšnjih raziskovalcev na tem področju. Matematični model in ustrezne diferencialne enačbe so bile rešene v programskem okolju Python ter dobljene koncentracije predstavljene z grafi. Raziskali smo tudi vpliv spremembe velikosti konstante hidrogenacije na sistem in koncentracijo vodikovega peroksida. Prav tako smo raziskali vpliv nižje temperature. Hydrogen peroxide is a chemical with an ever-growing global demand. For this reason, more and more research is devoted to the direct synthesis of H2O2 with the aim of replacing anthraquinone procces. Part of this work deals with the theoretical background of adsorption and different mechanisms for surface catalytic reactions. In addition, we have developed a mathematical model that accounts for the limiting factor of liquid-solid mass transfer. Mechanisms based on Langmuir-Hinshelwood and Eley-Rideal mechanisms were used for the reaction rates, leading to the corresponding constants found in the studies of previous researchers in this field. The mathematical model and differential equations were solved in the Python programming language, and the results were presented in graphs. In addition, we studied the effects of the size of the hydrogenation constant on the system and the hydrogen peroxide concentration. We also studied the effects of lower temperature on the system.

V okviru tega magistrskega dela smo raziskali vpliv strukture 1,2,4,5-tetraoksanov (TO) na njihovo termično stabilnost in herbicidno učinkovitost. V ta namen smo sintetizirali knjižnico dispiro-, spiro- in nespiro-TO iz aldehidov ali ketonov in vodikovega peroksida s ciklokondenzacijo katalizirano z HBF4 (0,2-2 ekv. napram karbonilnega substrata) v fluoriranem alkoholu TFE ali HFIP. Simetrične dispiro-TO sintetizane iz cikličnih ketonov smo izolirali z boljšimi izkoristki (64-76 %) kot simetrične nespiro-TO (44-46 %) sintetizirane iz acikličnih ketonov/aldehidov. Sinteza nesimetričnih TO je potekala preko tvorbe gemdihidroperoksida, ki je nastal s koncentriranjem mešanice določenega ketona in H2O2 v acetonitrilu pod znižanim tlakom. Temu je sledila ciklokondenzacija med nastalim gemdihidroperoksidom in izbranim ketonom/aldehidom v TFE/HFIP v prisotnosti HBF4. Sinteza nesimetričnih dispiro-TO je vodila do TO z zmernimi do odličnimi izkoristki (38- 93 %). Izvedena je bila nadaljnja modifikacija stranskih substituentov na cikloheksanskem obroču za vključitev dušikovega atoma v strukturo TO v obliki azidne ali amidne funkcionalne skupine. Dispiro-TO s karboksilno skupino vezano na cikloheksanski obroč smo zaestrili z 2-bromoetanolom z 72 % izkoristkom, in nato še bromov atom substituirali z azidno skupino s 87 % izkoristkom. Za redukcijo azidne skupine TO smo uporabili PPh3 v THF/H2O sistemu kot topilu. Redukcija je potekala z 38 % izkoristkom v 16 h in topilu DMF. Termična analiza sintetiziranih TO je bila izvedena z diferencialno skenirajočo kalorimetrijo (DSC). Simetrični dispiro-TO so bili termično bolj stabilni kot simetrični nespiro-TO. Vrednost temperature termičnega razpada za nesimetrične TO je bila med vrednostmi obeh simetričnih TO. Pri simetričnih dispiro-TO se je termična stabilnost povečala s polarnostjo stranskih substituent. Knjižnico TO smo uporabili za raziskovanje vpliva TO na kalitev in rast vrtne redkvice (Raphanus sativus L.). Vsi testirani TO so povzročili zaviranje kalitve semen, nekateri tudi zaviranje rasti korenin. Z merjenjem vsebnosti malondialdehida (MDA) smo posredno izmerili oksidativni stres v rastlinskih celicah, ki so bile izpostavljene različnim TO pri koncentracijah 0,015 mM, 0,15 mM, 1,5 mM, 15 mM ter 150 mM. Prisotnost simetričnega TO z estrsko funkcionalno skupino pripeto na stranski cikloheksanski obroč je pri koncentraciji 0,015 mM povzročila povečanje vsebnosti MDA v rastlinskih celicah, kar nakazuje, da je mehanizem herbicidnega delovanja tega TO povezan s povečanjem oksidativnega stresa. In the framework of this master's thesis, we studied the influence of 1,2,4,5-tetraoxanes (TO) structure on their thermal stability and potential herbicidal activity. For this purpose, we synthesized a library of dispiro-, spiro- and nonspiro-TO from aldehydes or ketones and H2O2 through acid-catalyzed cyclocondensation. Different amounts of HBF4 (0.2-2 eq. relative to the carbonyl substrate) were used in the syntheses in fluorinated alcohols TFE or HFIP as solvents. Symmetric dispiro-TO synthesized from cyclic ketones had better yields (64-76%) than symmetric nonspiro-TO (44-46%) synthesized from aliphatic acyclic ketones/aldehydes. Asymmetric TOs were synthetised from gem-dihydroperoxide, formed by concentrating a mixture of the chosen ketone and H2O2 in acetonitrile under reduced pressure. This was followed by cyclocondensation of the resulting gem-dihydroperoxide and the selected ketone/aldehyde in TFE / HFIP in the presence of HBF4. The synthesis of asymmetric dispiro-TOs led to TOs with moderate to high yields (38-93%). Further modification of the substituents at the cyclohexane ring was performed to incorporate a nitrogen atom into the TO structure as an azide or amide functional groups. A selected TO with carboxylic acid bound to cyclohexane ring was esterified with 2-bromoethanol with 72% yield, and then bromine was substituted with an azide group with 87% yield. PPh3 in THF/H2O solvent was used to reduce the azide group on the TO. The reduction was performed for 16 h in DMF and yielded 38% of the product. Thermal analysis of the synthesized TOs was performed by differential scanning calorimetry (DSC). Symmetric dispiro-TOs were thermally more stable than symmetric nonspiro-TOs. The value of the thermal decomposition temperature for asymmetric TOs was between the values of both corresponding symmetric TOs. In symmetric dispiro-TO, thermal stability increased as the polarity of the side substituents increased. The TO library was used to investigate the effect of TO on the germination and growth of radish (Raphanus sativus L.). All TO tested showed inhibition of seed germination, some also showed an inhibition of root growth. We indirectly measured the oxidative stress in plant cells exposed to different TOs at concentrations of 0.015 mM, 0.15 mM, 1.5 mM, 15 mM, and 150 mM by measuring the malondialdehyde (MDA) concentration. Treatment with 0,015 mM symmetric TO with cyclohexane ring bearing ester group as a side substituent resulted in increase of MDA concentration.

V zadnjih desetletjih se v kemijski industriji in širše pojavlja vedno večja potreba po vedno bolj učinkovitih separacijskih procesih, s katerimi pridobivamo čistejše vmesne in končne produkte. To je posledica ekonomskih prizadevanj za povečanje donosa proizvodnje in za minimizacijo stroškov, ki sta potrebna za zadovoljitev naraščajočih potreb trga, ter okoljskih prizadevanj za minimizacijo ali celo izničenje odpadnih produktov, ki nastajajo pri proizvodnji in ki trenutno še nimajo druge uporabe ali možnosti recikliranja, zaradi česar, v takšni ali drugačni obliki, pristanejo v okolju in s tem vplivajo na njegovo čistočo ter ravnovesje. Med podjetja, ki si za to prizadevajo, spada tudi Belinka Perkemija d. o. o. Tam, med drugim, poteka proizvodnja vodikovega peroksida po antrakinonskem procesu, pri katerem nastaja končni produkt v obliki vodne raztopine z visoko vsebnostjo organskih topil, ki jih je nato potrebno kar se da odstraniti. To se doseže z različnimi separacijskimi procesi, kot so: ekstrakcija, destilacija in membranska filtracija. V sklopu tega diplomskega dela se osredotočamo na membransko filtracijo, ki trenutno poteka z uporabo poliamidnih membran. Te membrane so cenovno ugodne in učinkovito odstranjujejo organska topila, a so relativno kratkotrajne, zaradi česar so manj priročne za kontinuirno uporabo. Zato smo kot potencialne alternative, na pilotni filtracijski napravi, eksperimentalno preizkusili keramične in kompozitne poliamidne-polipropilenske membrane različnih prepustnosti. Zaradi boljših kemijskih, termičnih in mehanskih lastnosti, predvsem pri keramičnih in manj pri polimernih membranah, je bila pričakovana daljša življenjska doba, a hkrati, kljub višji prepustnosti testiranih membran, vseeno zadovoljiva odstranitev organskih snovi. Ugotovljeno je bilo, da sta uporabljeni keramični membrani skoraj popolnoma neučinkoviti pri odstranjevanju organskih snovi v surovem vodikovem peroksidu. To je posledica prepustnosti membran, ki sta očitno imeli prevelike pore v primerjavi z velikostjo organskih molekul, da bi jih te lahko ločile od preostanka mešanice. Zaradi tako nizke učinkovitosti je bilo določeno, da se ne bo ugotavljalo obstojnosti keramičnih membran, saj bi bilo to nesmiselno in nemogoče. Po drugi strani pa je bila kompozitna polimerna membrana, ki je imela veliko nižjo prepustnost, zelo učinkovita pri odstranjevanju organskih snovi, a je zaradi težav pri testiranju prišlo do predčasnega uničenja membrane in posledično ni bilo možno eksperimentalno karakterizirati njene obstojnosti. Tako je bila kompozitna poliamidna-polipropilenska membrana, na podlagi rezultatov, ki smo jih uspeli pridobiti, izbrana za nadaljnje testiranje v sklopu optimizacije filtracijskega procesa, s katerim bodo pridobljeni odgovori na vprašanja, ki so v tem delu še ostala odprta, in s katerim bo ugotovljeno, ali je optimizacija industrijskega procesa filtracije s takimi membranami možna ter smiselna. In the last few decades, in the chemical industry and wider, there has been an ever greater demand for ever more effective separation processes, with which we produce cleaner intermediate and end products. This is the result of economic efforts to increase production output and to lower production costs, which are needed to accommodate the rising demands of the market, as well as environmental efforts to reduce or even eradicate waste products, which are created during production and for which we, as of now, don’t have any secondary use or the option of recycling, due to which these waste products, in some form or another, end up in the environment, thereby affecting it’s purity and balance. One company, which makes these efforts, is Belinka Perkemija d.o.o. Among other things, they produce hydrogen peroxide via the anthraquinone process, where the end product is acquired in the form of an aqueous solution with a high concentration of organic solvents, which then have to be removed. This is achieved by different separation processes, such as: extraction, distillation and membrane filtration. In this thesis we focus on membrane filtration, for which, at the moment, polyamide membranes are used. These membranes are relatively cheap and effective in removing organic solvents, but are quite short-lived, which is why they’re inconvenient for continuous operating conditions. This is why we conducted a pilot research with ceramic and composite polyamide-polypropylene membranes of different permeabilities, in hopes of finding a potential long-lived alternative. Due to better chemical, thermal and mechanical properties, especially of ceramic and less so of polymeric membranes, a longer membrane lifespan was expected, while also maintaining a satisfactory removal of organic compounds, in spite of higher permeabilities of the tested membranes. It was discovered, that both ceramic membranes, which were used, were almost completely ineffective in removing organic compounds in the crude form of hydrogen peroxide. This is the result of the permeabilities of these membranes, the pores of which were evidently too high, in comparison to the size of the organic molecules, to separate them from the rest of the mixture. As a result of such low rejection rates, it was decided, that the durability of these membranes wouldn’t be determined, as it was deemed to be not relevant and quite impossible. On the other hand, the composite polymeric membrane, which had a much lower permeability, was very effective in removing these organic compounds, but as a result of the filtration device malfunctioning, which led to the destruction of the membrane, the experiments had to be cut short and consequently it was not possible to determine it’s durability. In the end the composite polyamide-polypropylene membrane was selected for further testing, on the basis of the experimental evidence, which we had been able to gather. Future experiments will give us the answers to the questions, which have been left open in this thesis, as well as determine whether optimization of the industrial process with these membranes is possible and reasonable.

Uvod: Dentalna medicina primjenom inovativnih tehnika i materijala teži uspostavljanju bioloških procesa i regeneraciji tkiva u svrhu očuvanja zuba u žvačnoj, estetskoj i fonetskoj funkciji. Evolucijom estetske dentalne medicine lijep osmijeh pacijentima je postao imperativ, stoga je izbjeljivanje zubi sve traženiji zahvat. Cilj prikaza ovog kliničkog slučaja je pokazati učinkovitost i uspješnost kombinirane tehnike internog i eksternog izbjeljivanja zuba nakon jednoposjetnog endodontskog liječenja. Materijali i metode: Detaljnom anamnezom, kliničkim i radiološkim pregledom te testovima senzibiliteta utvrđena je nekroze pulpe zuba 13. Nakon provedenog jednoposjetnog endodontskog liječenja pristupilo se internom „walking bleach“ izbjeljivanju primjenom 3% vodikovog peroksida i natrijevog perborata koji se mijenjao dva puta unutar sedam dana. Eksterno izbjeljivanje provelo se 35% karbamid peroksidom tjedan dana po završetku internog izbjeljivanja. Proces izbjeljivanja završen je izradom kompozitnog ispuna i poliranjem zuba. Rezultati: Mjesec dana nakon provedenih terapijskih postupaka pacijentica ima uredan klinički nalaz. Kontrolni pregled uz radiološku analizu provest će se nakon šest mjeseci. Zaključak: U odnosu na konvencionalne tehnike liječenja u području endodoncije i restaurativne dentalne medicine, primjenom novijih dijagnostičko-terapijskih postupaka pacijent može u suradnji sa svojim liječnikom udovoljiti visokim zahtjevima suvremene dentalne medicine

Velika proizvodnja i upotreba nanočestica srebra (AgNPs) dovode do ispuštanja istih u morski okoliš što posljedično može dovesti do smrtnosti različitih morskih organizama. Dosadašnja istraživanja dokazala su toksičnost AgNPs na morskim beskralješnjacima i fitoplanktonu. No potrebno je istražiti utjecaj istih na primarne proizvođače poput morskih makroalgi. Morske makroalge vrlo su bitan dio morskog ekosustava. One obogaćuju morski okoliš kisikom, važna su hrana herbivornim vrstama organizama te pružaju stanište i skrovište različitim vrstama kralješnjaka i beskralješnjaka. Cilj ovog rada bio je ispitati kako različite veličine nanočestica srebra utječu na toksičnost kod crvene morske makroalge Laurencia obtusa. Toksičnost AgNPs ispitana je uz pomoć testova lipidne peroksidacije i sadržaja vodikovog peroksida. Talusi morske makroalge L. obtusa izloženi su AgNPs veličina 20 i 60 nm u koncentracijama od 1, 10 i 100 μg/mL tijekom 24 sata. Rezultati testa lipidne peroksidacije pokazali su najveću toksičnost Ag60 u koncentraciji od 100 μg/mL, a Ag20 nisu značajno utjecale na lipidnu peroksidaciju u L. obtusa. Rezultati sadržaja vodikovog peroksida također su ukazali na veću toksičnost Ag60, ali pri najmanjoj koncentraciji. U oba testa AgNPs pokazale su veću toksičnost od Ag+ iona. Vidljivo je da u istraživanju s crvenim makroalgama veće AgNPs imaju veći utjecaj na toksičnost. Također toksičnost AgNPs ovisi o primijenjenoj koncentraciji. No, potrebno provesti daljnja istraživanja kako bi se sa sigurnošću utvrdio utjecaj AgNPs na morske makroalge.

Sunčevo zračenje je izvor energije za fotosintezu i važan signal za regulaciju rasta i razvoja biljaka. Međutim, svjetlost visokog intenziteta, a posebno ultraljubičasti zračenje, može izazvati stres u biljaka. Mjerenjem količine H2O2, prolina, stupnja lipidne peroksidacije, aktivnosti antioksidacijskih enzima i učinkovitosti fotosinteze moguće je procijeniti učinak stresnih uvjeta na biljke. Cilj ovog istraživanja bio je procijeniti učinak UVB-zračenja na modelnu biljku Arabidopsis thaliana. Osim divljeg tipa, koristila sam linije oeBPM1 i amiR-bpm koje imaju promijenjenu ekspresiju gena BPM. Protein BPM1 pripada porodici proteina MATH-BTB (BPM) koji u biljci sudjeluju u razvojnim procesima i odgovoru na stresne uvjete. Imunodetekcijom proteina BPM1-GFP u linije oeBPM1 potvrdila sam akumulaciju tog proteina nakon izlaganja dozi UV-zračenja od 831 J cm-2 . Primjenom te doze UVB-zračenja i usporedbom kontrolnih i tretiranih biljaka potvrdila sam razliku u količini H2O2 u biljaka divljeg tipa i liniji oeBPM1, u aktivnosti gvajakol peroksidaze i superoksid dismutaze u biljaka divljeg tipa te u maksimalnom kvantnom prinosu PSII u liniji oeBPM1. Veću razliku uočila sam između linija nego između kontrolnih i tretiranih biljaka. Linija oeBPM1 pokazala je bolji odgovor na stres u odnosu na druge dvije linije zbog izrazitije aktivacije antioksidacijskih enzima, dok je linija amiR-bpm imala višu razinu H2O2 i lipidne peroksidacije u odnosu na divlji tip i liniju oeBPM1. Budući da se navedene linije razlikuju u ekspresiji gena BPM, moguća je njihova uključenost u odgovor na UVB-zračenje. Solar radiation is a source of energy for photosynthesis and an important signal for regulation of plant growth and development. However, high light intensity, and especially ultraviolet radiation, can cause stress in plants. H2O2 and proline content, lipid peroxidation level, activity of antioxidant enzymes and efficiency of photosynthesis are measurable parameters for assessing the stress effect on plants. The main goal of the research was to evaluate the effect of UV-B radiation on model plant Arabidopsis thaliana. Besides wild-type, the lines with modified expression of BPM genes (oeBPM1 and amiR-bpm) were used. BPM1 protein belongs to the MATH-BTB (BPM) protein family that participate in developmental processes and stress response in plants. Immunodetection of BPM1-GFP protein in oeBPM1 confirmed the highest accumulation of the protein after treatment with UV-B radiation dose of 831 J cm-2 . The comparison of control and treated plants showed that this dose of UV-B radiation induced changes in the content of H2O2 in wild type and oeBPM1, in guaiacol peroxidase and superoxide dismutase activity in wild type, and in the maximum quantum efficiency of PSII in oeBPM1. Moreover, a difference between tested lines was more pronounced than difference between control and treated plants of the same line. The oeBPM1 line showed better stress response than other two lines due to more pronounced activation of antioxidant enzymes, while the amiR-bpm line had higher H2O2 content and lipid peroxidation level compared to wild type and oeBPM1. Because these lines differ in expression of BPM genes, their involvement in the UV-B radiation response is possible.

In the Water, Energy and Waste Directive, the European Commission provides for the use of household washing programmes with lower temperatures (30–40 °C) and lower water consumption. However, low washing temperatures and the absence of oxidising agents in the liquid detergents, and their reduced content in powder detergents, allow biofilm formation in washing machines and the development of an unpleasant odour, while the washed laundry can become a carrier of pathogenic bacteria, posing a risk to human health. The aim of the study was to determine whether the addition of hydrogen peroxide (HP) to liquid detergents in low-temperature household washing allows disinfection of the laundry without affecting the properties of the washed textiles even after several consecutive washes. Fabrics of different colours and of different raw material compositions were repeatedly washed in a household washing machine using a liquid detergent with the addition of 3% stabilised HP solution in the main wash, prewash or rinse. The results of the antimicrobial activity, soil removal activity, colour change and tensile strength confirmed the excellent disinfection activity of the 3% HP, but only if added in the main wash. Its presence did not discolour nor affect the tensile strength of the laundry, thus maintaining its overall appearance.

Namen diplomske naloge je bil spremljanje razpada razredčenih vodnih raztopin vodikovega peroksida pri različnih koncentracijah ter preučevanje vpliva citronske in dipikolinske kisline na njihovo stabilnost. Razpad vodikovega peroksida sem spremljala s stresnim testom z zasledovanjem začetne in končne koncentracije raztopin, pred in po segrevanju po 16 urah pri 96 °C, z namenom ugotoviti, katera izmed testiranih kislin bolje stabilizira razredčene vodne raztopine vodikovega peroksida. Takšne raztopine vodikovega peroksida so primerne za splošno dezinfekcijo in uporabo v prehrambni industriji. The aim of this work was to observe the decomposition of dilute aqueous solutions of hydrogen peroxide at different concentrations and to study the influence of citric and dipicolinic acids on their stability. The decomposition of hydrogen peroxide was monitored by a stress test in which the initial and final concentrations of the solutions were monitored before and after heating to 96°C for 16 hours. The objective was to determine which of the acids tested more strongly stabilized dilute aqueous solutions of hydrogen peroxide. Such hydrogen peroxide solutions are suitable for general disinfection and use in the food industry.

Cilj dela je bil razvoj elektrokemijskega plinskega senzorja za detekcijo perokso zvrsti s pomočjo tiskanih elektrodnih sistemov. Modifikacijo delovne elektrode sem izvedel z nanosom nanostrukturiranih senzorskih materialov, najpogosteje iz vodnih suspenzij. Uporabil sem različne gelske elektrolite na osnovi poliakrilne kisline, ki niso služili le kot elektrolit, ampak tudi kot sredstvo za predkoncentracijo in stabilizacijo vodikovega peroksida in nato triaceton triperoksid (TATP) eksploziva. Za karakterizacijo senzorja za detekcijo vodikovega peroksida v plinski fazi sem uporabil ciklično voltametrijo, za samo detekcijo pa pulzno amperometrijo. Optimiziral sem ključne detekcijske parametre, kot so koncentracija katalitskega materiala, pH elektrolita, čas akumulacije, potencial itd. Nato sem sintetiziral modelni organski perokso eksploziv TATP, in ga uspešno določal v plinski fazi s prej omenjenim senzorjem. Za validacijo metode sem uporabil standardno analizno metodo na osnovi plinske kromatografije, sklopljene z masno spektrometrijo (GC-MS). The goal of the present thesis was the development of electrochemical gas sensor for the detection of peroxo species with the help of printed electrode systems. Modification of the working electrode was made by coating the surface with nanostructured sensor materials, mostly from water suspensions. Gel electrolytes based on polyacrylic acid were used, which besides working as electrolytes acted as mediums for the stabilization and preconcentration of hydrogen peroxide and later triacetone triperoxide (TATP) explosive. Cyclic voltammetry was used for the characterisation of the sensor for the detection of hydrogen peroxide in gaseous phase, while pulse amperometry was used for its detection. Key detection parameters were optimised like the concentration of catalytic material, pH of the electrolyte, time of accumulation, potential etc. Then a model organic peroxo explosive TATP was synthesised and successfully detected in gaseous phase by the same sensor. For validation of the method a standard analytical method on the basis of gas chromatography coupled with mass spectrometry (GC-MS) was used.

Four different graphene-based nanomaterials (htGO, N-htGO, htGONR, and N-htGONR) were synthesized, characterized, and used as a modifier of carbon paste electrode (CPE) in order to produce a reliable, precise, and highly sensitive non-enzymatic amperometric hydrogen peroxide sensor for complex matrices. CPE, with their robustness, reliability, and ease of modification, present a convenient starting point for the development of new sensors. Modification of CPE was optimized by systematically changing the type and concentration of materials in the modifier and studying the prepared electrode surface by cyclic voltammetry. N-htGONR in combination with manganese dioxide (1:1 ratio) proved to be the most appropriate material for detection of hydrogen peroxide in pharmaceutical and saliva matrices. The developed sensor exhibited a wide linear range (1.0–300 µM) and an excellent limit of detection (0.08 µM) and reproducibility, as well as high sensitivity and stability. The sensor was successfully applied to real sample analysis, where the recovery values for a commercially obtained pharmaceutical product were between 94.3% and 98.0%. Saliva samples of a user of the pharmaceutical product were also successfully analyzed.

V diplomski nalogi sem spremljal razpad razredčenih raztopin vodikovega peroksida različnih koncentracij ter vpliv citronske in dipikolinske kisline na njegovo stabilnost. Z izvajanjem jodometričnih titracij sem spremljal koncentracijo raztopin vodikovega peroksida pred in po opravljenem stresnem testu stabilnosti. Primerjal sem vpliv izbranih organskih kislin na stabilnost vodikovega peroksida v formulacijah, ki so zanimive za dezinfekcijo in prehrambeno industrijo. In my thesis, I investigated the decomposition of dilute solutions of hydrogen peroxide of various concentrations and the influence of citric and dipicolinic acids on its stability. By iodometric titrations, I monitored the concentration of hydrogen peroxide solutions before and after performing the stress stability test. I compared the effect of selected organic acids on the stability of hydrogen peroxide in formulations of interest to the disinfection and food industries.

Amoxicillin (AMX) and Ciprofloxacin (CIP) are antibiotics commonly used in human medicine with high environmental toxicity and poor biodegradability. They have been found in various hospital effluents and groundwater, and their environmental impact is still not fully understood. In this work, we investigated the possibility of treating model wastewaters containing the antibiotics AMX and CIP using ozonation, with the addition of H2O2 under various conditions, including different pH values, H2O2, and ozone dosages. The quantification of and treatment efficacy for antibiotic removal were determined via solid phase extraction followed by chromatographic separation by liquid chromatography coupled with tandem triple quadrupole mass spectrometry (LC/MS/MS). This analytical system is quite efficient for the detection of all major antibiotic classes, even if they are present at very low concentrations. The efficiency of ozonation was determined by measuring the TOC (Total Organic Carbon) changes after ozonation of the model wastewater and by measuring the concentration of the two antibiotics. In a sequential activated sludge process of ozone-treated model wastewater, almost complete TOC removal and an overwhelming decrease in antibiotic concentrations (up to 99%) were observed. Ozonation resulted in complete removal of AMX and CIP in less than 30 and 120 min, respectively. The results of this work indicate that ozonation could be a suitable pretreatment method to reduce the toxicity of contaminants (AMX and CIP) and improve the biodegradability of hospital wastewater.

Antiparazitici se ubrajaju u nova onečišćivala vode s obzirom da je nedavno istaknut njihov potencijalan negativan utjecaj na okoliš. Izlučevinama životinja i ljudi lako dospijevaju u tla i vodu gdje imaju negativan utjecaj na ostale organizme. Također, prisutstvo mikroplastike u vodama je rastući problem s utvrđenim negativnim utjecajima na zdravlje ljudi i životinja. Mikroplastika je veličine manje od 5 nm te iznimno heterogenog sastava čime je njena učinkovita eliminacija iz vode velik izazov te čest predmet istraživanja. Kvantifikacija i identifikacija antiparazitika albendazola, mebendazola te febantela u uzorcima provedena je tekućinskom kromatografijom visoke djelotvornosti. Potrebne su daljnje analize da bi utvrdili o kojim se razgradnim produktima radi. Razgradnja antiparazitika se nastojala potaknuti mehaničkim miješanjem u prisutstvu vodikova peroksida te natrijeva hipoklorita. Provedeni su eksperimenti fotolize primjenom umjetnog Sunčevog zračenja kako bi se ispitala mogućnost razgradnje antiparazitika djelovanjem fotona. Ovi simulirani uvjeti su ispitani i u prisutstvu mikroplastike kako bi se pratio njen moguć utjecaj na njihovu razgradnju. Rezultati su pokazali različit postotak razgradnje između tri navedena antiparazitika. Količina razgradnih produkata se razlikuje ovisno o ispitivanom antiparazitiku, pH-vrijednosti te koncentraciji korištenog reagensa. Prisutstvo mikroplastike u simuliranoj otpadnoj vodi nije utjecalo na promjenu razgradnje antiparazitika neovisno o provođenom testu. Antiparasitics are among the new water pollutants, given that their potential negative impact on the environment has recently been highlighted. By secretions of animals and humans, they can easily reach the soil and water where they have negative impact on other organisms. Also, the presence of microplastics in water is a growing problem with confirmed negative effect on human and animal health. Microplastics are smaller than 5 nm in size and have an extremely heterogeneous composition, which makes its effective elimination from water a great challenge and frequent subject of research. In this research, using HPLC equipment, the composition of degradation products according to the similiraties of the absorption spectrum was analysed for the antiparasitics albendazole, mebendazole and febantel. Degradation of antiparasitics was attempted by mechanical mixing in the presence of hydrogen peroxide and sodium hypochlorite. Solar radiation was also simulated in order to research the possibility of antiparasitics degradation by the action of photons. These simulated conditions were also examined in the presence of microplastics to monitor its possible impact on their degradation. The results showed different percentage degradation between the three mentioned antiparasitics. The amount of degradation products varies depending on the tested antiparasitic, pH value and concentration of the used reagent. Presence of microplastics in the simulated wastewater did not affect the change in degradation of antiparasitics regardless of the test performed.

High levels of reactive oxygen species (ROS) can lead to impairment of cell structure, biomolecules' loss of function and cell death and are associated with liver diseases. Cells that survive increased ROS often undergo malignant transformation. Many cancer cells tolerate high levels of ROS. Here we report a transiently increased production of H$_2$O$_2$ and concomitant upregulation of antioxidative enzymes triggered by hepatocyte isolation the H$_2$O$_2$ levels revert in about two days in culture. Three-day survival rate of the isolated cells in the presence of 2.5-fold increase of H$_2$O$_2$ is almost 80%. Apoptosis activation through the mitochondrial pathway is meanwhile reduced by inhibition of caspase-9 triggering. This reduction depends on the amount of H$_2$O$_2$ production, as decreased production of H$_2$O$_2$ in the presence of an antioxidant results in increased apoptosis triggering. These stress adaptations do not influence urea production, which is unchanged throughout the normal and stress adapted phases. We conclude that hepatocytes' stress adaptation is mediated by increased ROS production. In this case, high ROS improve cell survival.

V diplomski nalogi sem spremljala razpad razredčenega vodikovega peroksida v vodnih in alkoholnih raztopinah različnih koncentracij in vpliv različnih organskih kislin na njegovo stabilnost. S pomočjo jodometrične titracije sem spremljala začetno in končno koncentracijo raztopine. Moj cilj je bil ugotoviti, katere organske kisline najbolj stabilizirajo oziroma preprečijo razpad vodikovega peroksida v razredčenih raztopinah. In this work, the decomposition of dilute solutions of hydrogen peroxide in water and alcohols as solvents and the influence of various organic acids on the stability of hydrogen peroxide were studied. The changes in initial and final concentrations of hydrogen peroxide solutions were followed by iodometric titration. The aim of this work was to find out which organic acids are most suitable for stabilizing hydrogen peroxide solutions and preventing their decomposition.

Oomicetni mikroorganizam Saprolegnia parasitica oportunistički je patogen koji izaziva saprolegniozu, bolest koja uzrokuje velike gubitke u salmonidnoj akvakulturi. Neke od kemikalija koje su se do nedavno koristile za suzbijanje saprolegnioze zabranjene su u Europskoj uniji zbog kancerogenosti i toksičnosti te je potreban razvoj novih, ekološki prihvatljivih tretmana. Plazmom aktivirana voda (engl. Plasma Activated Water, PAW) ima široki raspon primjena zbog dokazanog antimikrobnog učinka i niskog rizika za zdravlje ljudi i okoliš. S obzirom da primjena PAW još nije testirana u akvakulturi, cilj ovog rada bio je po prvi puta istražiti može li PAW inhibirati rast micelija vrste S. parasitica. Micelij je tretiran s PAW kroz 30 i 60 minuta te su rezultati uspoređeni sa tretmanom vodikovim peroksidom kao pozitivnom kontrolom i vodom (engl. Artificial Water, AW) kao negativnom kontrolom. Utvrđeno je da tretiranje micelija s PAW kroz 60 minuta uzrokuje sporiji rast patogena (do 33 % smanjeni rast u odnosu na negativnu kontrolu). U usporedbi s tim, rast micelija bio je potpuno inhibiran nakon tretmana vodikovim peroksidom koncentracije 1000 mg/L u trajanju od 60 minuta. Zaključno, iako utjecaj PAW na micelij S. parasitica nije bio jednako snažan kao djelovanje vodikovog peroksida, ovo istraživanje otvorilo je mogućnost primjene PAW, kao ekološki prihvatljivog tretmana, u akvakulturi.

Reaktivne kisikove vrste (ROS, engl. Reactive oxygen species) su nužne za funkcioniranje fizioloških procesa u stanicama, no mogu doprinijeti i razvoju bolesti kao što su tumori. Nepoželjno djelovanje ROS-a nastupa uslijed njihove nedostatne eliminacije antioksidansima tijekom oksidacijskog stresa (OS). Osim što je OS uključen u sve faze nastanka i razvoja tumora, u samih je tumorskih stanica pokazana povećana razina ROS-a u odnosu na zdrave, karakteristika koju iskorištava većina konvencionalne terapije bazirane na selektivnom povećanju ROS-a. Kako ne bi došlo do smrti zbog oksidacijskih oštećenja, tumorske stanice često imaju i pojačane antioksidacijske mehanizme zaštite te mijenjaju svoj metabolizam sukladno potrebama rasta. Heterogenost samih tumora doprinosi različitim odgovorima na terapiju. Ovim je istraživanjem ispitivan utjecaj duljine izloženosti različitim koncentracijama vodikovog peroksida na trima tipovima staničnih linija tumora dojke: MCF-7 (hormonski pozitivne), SkBr-3 (HER2 pozitivne) i SUM 159 (trostruko negativne). Proučavana je stanična vijabilnost, razina endogenih ROS-a, te ekspresija proteina i aktivnost glutationa i katalaze radi otkrivanja potencijalnih razlika u antioksidacijskoj zaštiti i aktivaciji metabolizma. Rezultati ukazuju na razlike u odgovoru staničnih linija u ovisnosti o koncentraciji i duljini izloženosti vodikovom peroksidu. Stanična linija MCF-7 se pokazala najmanje osjetljivom, dok je SUM 159 bila najosjetljivija. Although necessary for physiological cell functions, reactive oxygen species (ROS) can also contribute to the development of diseases such as tumors. Their detrimental effect is associated with their insufficient elimination by antioxidants during oxidative stress (OS). In addition to OS being involved in all stages of tumor development and progression, tumor cells have been shown to have increased levels of ROS compared to healthy ones, a feature exploited by most conventional therapies based on selective ROS augmentation. To avoid oxidative damage-induced death, tumor cells often enhance antioxidant defense mechanisms and reprogram their metabolism to boost tumor growth. The heterogeneity of the tumors contributes to different responses to therapy. This study aimed to investigate the effect of length of exposure to different concentrations of hydrogen peroxide on three breast cancer cell lines: MCF-7 (hormone positive), SkBr-3 (HER2 positive), and SUM 159 (triple-negative). Cell viability, endogenous levels of ROS, protein expression, and glutathione and catalase activity were studied to explore potential differences in antioxidative capacity and metabolic activation. The results indicate cell line-dependent response to concentration and length of exposure to hydrogen peroxide. The MCF-7 cell line was the least sensitive, while the SUM 159 was the most sensitive.

Jodirane organske molekule so izredno pomembni intermediati v sintezni organski kemiji, saj se jih uporablja pri uvajanju C-C, C-N in C-O vezi v sistem. Poleg bistvenega pomena v kemiji, pa se vedno bolj uveljavljajo v medicini in farmaciji. V nuklearni medicini sta jodova izotopa 123I in 124I uvedena v različne molekule, ki nastopajo kot diagnostični markerji. Za boljšo učinkovitost metod jodiranja je bilo na začetku potrebno raziskovanje bioloških poti uvajanja halogenov v molekule, iz tega pa so se razvili različni pristopi k reševanju problema, kako na okolju prijazen način čim bolj selektivno in učinkovito pridobiti željene jodirane aromate. Najbolj logična izbira iz vidika zelene kemije je oksidativno jodiranje, ki omogoča boljšo ekonomiko jodovih atomov, saj se ob uporabi molekularnega joda in sočasni prisotnosti oksidanta nastajajoči HI pri jodiranju pretvori nazaj v elektrofilen jod. Izbira oksidanta pa po zgledu iz narave vodi do vodikovega peroksida in kisika, ker pri uporabi le teh ne nastajajo škodljivi stranski produkti, ampak le voda. V diplomski nalogi sem opisala dostopne metode za uvajanje več jodovih atomov v aromatski obroč. Ugotovila sem, da je nabor možnosti velik, vendar sem ob natančnejši študiji prišla do tistih metod, ki ponujajo dobre izkoristke in selektivnost ter so manj obremenjujoče za okolje. Najosnovnejša metoda je oksidativno jodiranje ob prisotnosti kisline kot katalizatorja, ki se izkaže za uspešno metodo. Korak naprej proti zeleni kemiji pa nudita oksidativno jodiranje v vodi ali pa oksidativno jodiranje brez uporabe topila, saj so organska topila med bolj problematičnimi komponentami procesov zaradi velike količine in njihove toksičnosti. Sistem jodiranja z uporabo zračnega kisika kot oksidanta prav tako omogoča uvajanje jodovih atomov v molekule. Zaradi širokega spektra pristopov k izvajanju reakcij je možno uporabiti tudi drugačne pristope, kot je elektrokemijsko jodiranje, jodiranje s pomočjo ultrazvočne kavitacije in jodiranje z mletjem. Iodinated organic molecules are extremely important intermediates in organic synthesis, as they are used for the introduction of C-C, C-N and C-O bonds into the system. In addition to being essential in chemistry, they are gaining ground in medicine and pharmacy. In nuclear medicine, the iodine isotopes 123I and 124I are introduced into various molecules, which act as diagnostic markers. In order to improve the efficiency of iodination methods, it was necessary to study the biological pathways of halogen introduction into molecules, which enabled the development of various approaches to obtain the desired iodinated aromatics as selectively and efficiently as possible in an environmentally friendly way. The most logical choice from the point of green chemistry is oxidative iodination, which allows a better economy of iodine atoms, because when molecular iodine is used in the presence of an oxidant, the by-product HI is converted back to molecular iodine. The choice of oxidant, following examples from nature, leads to hydrogen peroxide and oxygen, because their use does not produce any harmful by-products, only water. In my undergraduate thesis, I described the available methods for introducing several iodine atoms into an aromatic ring. I found the list of possibilities to be big, but on closer study I came up with those methods that offer good yields, are selective and are less harmful to the environment. The most basic method is oxidative iodination in the presence of acid as a catalyst, which is proving to be a successful method. However, a step forward towards green chemistry is offered by oxidative iodination in water or under solvent-free conditions, as organic solvents are probably one of the most problematic components of processes due to their high usage and toxicity. The iodination system using air as an oxidant also allows the introduction of iodine atoms into the molecules. Because of the variety of approaches to carry out reactions, it is also possible to use alternative methods, such as electrochemical iodination, iodination by ultrasound cavitation and method by grinding.

Izbjeljivanje vitalnih zubi mora se provoditi vrlo pedantno kako ne bi došlo do iritacije pulpe. Oni se mogu izbjeljivati na 3 načina: izbjeljivanjem u ordinaciji pod strogim nadzorom stomatologa, izbjeljivanjem kod kuće i njihovom kombinacijom. Odabir najpodobnije tehnike za pacijenta ovisi prije svega o etiologiji i intenzitetu obojenja. Postupak se provodi kemijskim sredstvima kao što su vodikov peroksid i karbamidov peroksid, a može biti potpomognut primjenom svijetla ili topline. Kombinirana tehnika izbjeljivanja vitalnih zubi u novije vrijeme postaje sve popularnija. Dokazala se izrazito učinkovitom i neinvazivnom metodom, a dobiveni su rezultati jako dobri i dugotrajni. Zubi se prvo tretiraju 6% vodikovim peroksidom u ordinaciji, a zatim 16% karbamidovim peroksidom kod kuće, u prethodno individualno izrađenoj udlagi, kroz period od dva do tri tjedna. Rizik od nastanka nuspojava na tvrdim i mekim tkivima usne šupljine sveden je na minimum. Prema Direktivi Europske Unije (2011/84/EU), donja dobna granica za izbjeljivanje zubi iznosi 18 godina. Tom se Direktivom definirala koncentracija vodikovog peroksida koju smiju koristiti stomatolozi, odnosno pacijenti pod njihovim nadzorom, a iznosi od 0,1 do 6 %. Nisu svi pacijenti dobri kandidati za postupak izbjeljivanja. Zato je potrebno napraviti temeljiti klinički pregled, te utvrditi postojanje indikacija i kontraindikacija. Ponekad samo saniranje karijesnih lezija, profesionalno čišćenje tvrdih i mekih naslaga te poliranje abrazivnom pastom daje zadovoljavajuće rezultate. Najbolji rezultati izbjeljivanja postižu se na onim zubima koji imaju svijetla žućkasta i smeđa obojenja, a najslabije se izbjeljuju tamno plave i sive nijanse Vital teeth whitening must be carried out very thoroughly in order to avoid pulp irritation. Teeth whitening can be done in three ways: intensive whitening in the office under the strict supervision of a dentist, whitening at home and a combination of these two tehniques. Choosing the most appropriate tehnique for the patient depends primarly on the etiology of the discoloration. The process is carried out with chemical agents such as hydrogen peroxide and carbamide peroxide, and can be aided by the application of light or heat. The combined technique of whitening vital teeth has become increasingly popular in recent times. It has proven to be a very effective and non-invasive method, and the results are very good and long lasting. The teeth are first treated with 6% hydrogen peroxide in the office and then with 16% carbamide peroxide at home, in previously individually prepared splinters, for a period of two to three weeks. The risk of side effects on hard and soft tissues of the oral cavity is minimized. According to the Directive of the European Union (2011/84/ EU), the lower age limit for teeth whitening is 18 years. This Directive defines the concentration of hydrogen peroxide that can be used by dentists or patients under their supervision, ranging from 0.1 to 6%. Not all patients are good candidates for the bleaching process. Therefore, a thorough clinical examination should be made and indications and contraindications established. Sometimes just repairing caries lesions, professionally cleaning hard and soft deposits and polishing with an abrasive paste gives satisfactory results. The best whitening results are achieved on those teeth that have light yellowish and brown discolorations, and the weakest whiten in dark blue and gray shades.

Berlinsko modrilo (PB) poznato je kao efikasan katalizator pri elektrokemijskoj redukciji vodikova peroksida. U ovom radu pokazano je da filmovi berlinskog modrila s intersticijski ugrađenim cezijevim ionima, umjesto tipično ugrađenih intersticijskih iona kalija, pokazuju unaprijeđena elektrokatalitička svojstva (k(Cs-PB) = 3,1 · 106 cm3 mol–1 s–1; k(K-PB) = 2,3 · 106 cm3 mol–1 s–1) te bolju stabilnost pri višim koncentracijama H2O2 (c(H2O2) = 0,1 mol dm–3). Elektrogravimetrijskim mjerenjima pokazano je da prilikom redukcije Cs-PB kao protuinoni konkuriraju H+ i Cs+ (N(H+) : N(Cs+) = 1,11) u značajnijoj mjeri nego pri redukciji K-PB (N(H+) : N(K+) = 0,16). S obzirom da su rezultati provedenih spektroelektrokemijskih mjerenja pokazali da, neovisno o vrsti ugrađenog intersticijskog kationa, filmovi PB pokazuju vrlo sličnu strukturu u smislu udjela FeN6 i FeN(6–x)Ox redoks-centara, opažena bolja elektrokatalitička svojstva Cs-PB u odnosu na K-PB i Na-PB pripisana su upravo većem udjelu iona H+ u kristalnoj rešetki PB te njihovoj većoj pokretljivosti. Prussian blue (PB) is known as an efficient catalyst for hydrogen peroxide reduction. This work demonstrates enhanced electrocatalytic properties of a thin film which contains cesium ions instead of potassium, which are usually used (k(Cs-PB) = 3.1 · 106 cm3 mol–1 s–1; k(K-PB) = 2.3 · 106 cm3 mol–1 s–1). Better stability of Cs-PB thin film, compared to K-PB film, in the presence of higher concentration of hydrogen peroxide (c(H2O2) = 0,1 mol dm–3) is also presented. Results obtained by electrogravimetry demonstrate higher competition of H+ and Cs+ ions during the reduction of Prussian blue film (N(H+) : N(Cs+) = 1.11; N(H+) : N(K+) = 0.16). Considering the fact obtained by spectroelectrochemistry which suggests similar structure of K-PB and Cs-PB films (almost equal content of FeN6 and FeN(6–x)Ox redox centers), better electrocatalytic properties of Cs-PB film are ascribed to higher content of H+ ions in Prussian blue lattice and their higher mobility.

U ovom radu su razvijeni kompozitni materijali sol-gel postupkom koji su sadržavali ugljikove materijale te ugljikove materijale i ternarni sulfid AgCuS. Razvijeni kserogelni kompoziti su upotrijebljeni kao osjetilni elementi u poli(vinil) klorid matricama za modificiranje površine elektrode od staklastog ugljika. Ispitivano je elektrokemijsko ponašanje ovih elektroda u prisutnosti vodikovog peroksida. Elektrokemijski procesi uočeni na elektrodama modificiranim s kompozitima koji su sadržavali AgCuS ukazuju mogućnost direktnog određivanja vodikovog peroksida na anodnim potencijalima od +0,3 V. Mjerenja su vršena pri tri pH vrijednosti (pH 5, 7 i 9) te je kao optimalna pH vrijednost odabrana pH = 9. Kao pogodna metoda pokazala se amperometrija. Amperometrijska mjerenja su pokazala mogućnost određivanja vodikovog peroksida u području koncentracija od 5-90 µg cm -3 s osjetljivošću od 1,47 nA cm 3 µg -1 i granicom detekcije od 0,12 µg cm -3 te granicom određivanja od 0,42 µg cm -3 . This paper investigated the development of composite materials useing sol-gel method which contained carbon materials as well as carbon materials with ternar sulfid AgCuS. The developed xerogel composites are used as a sensoring element in poli(vinil-chloride) matrices for modificating the surface of glasy carbon electrodes. Electrochemical behaviour of these electrodes were tested in presence of hydrogen peroxide. The electrochemical behaviour spotted on the electrodes modified with composite AgCuS show the posibility of direct detection of hydrogene peroxide on + 0,3 V anode potential. The measurements were made at three different pH values (pH 5, 7, and 9) and pH 9 was chosen to be the optimal pH value. Amperometry has proved to be a suitable method for measuring. Amperometric measurements have shown a posibility of detection of hydrogene peroxide in concentration ranging from 5 to 90 µg cm -3 with the value of sensibility of 1,47 nA cm 3 µg -1 , a detection limit of 0,12 µg cm -3 and a limit of determination of 0,42 µg cm -3 .

V doktorski disertaciji so predstavljene nove metode za določevanje težkih kovin v sledovih. Kot alternativa živosrebrni elektrodi sta bili v zadnjem desetletju predstavljeni bizmutova in antimonova elektroda, mehanizem delovanja teh elektrod pa do sedaj še ni bil pojasnjen. V doktorskem delu je predstavljena študija delovanja elektrod pri različnih pogojih elektroanalize s tehniko elektrokemijske impedančne spektroskopije (EIS). Uporabili smo nemodificirano elektrodo iz steklastega ogljika (GCE) in modificirano elektrodo z različnimi in situ pripravljenimi prevlekami na njeni površini (prevleka iz bizmuta BiFGCE in prevleka iz antimona SbFGCE) za določanje Zn(II), Cd(II) in Pb(II). Metode smo pred EIS analizo delno validirali (meja zaznavnosti, meja določljivosti, linearnost, občutljivost, točnost, natančnost). Za pripravo BiFGCE smo uporabili dve različni koncentraciji 0,5 mg/L in 1,0 mg/L Bi(III) v elektrolitu 0,1 M acetatnem pufru, za pripravo SbFGCE pa 0,5 mg/L Sb(III) v elektrolitu 0,1 M acetatnem pufru ali 0,01 M HCl. Z EIS-analizami BiFGCE pri različnih potencialih smo ugotovili, da se prevleka, nastala pri določenem potencialu elektronalaganja, enako obnaša v svojem naravnem stanju, zato je primerna za elektroanalizo. Z uporabo modelov ekvivalentnih električnih vezij (EEC) smo pridobili parametre za opis delovanja BiFGCE. Ugotovili smo, da različni dodatki težkih kovin v raztopino z elektrolitom nimajo signifikantnega vpliva na delovanje BiFGCE oziroma na kapacitivnost in polarizacijsko upornost BiFGCE. Za različne sisteme smo uporabili različne EEC in ugotovili, da delovanje BiFGCE pri določanju težkih kovin pri različnih pogojih analize (na primer potencialih elektronalaganja) ni enaki proces. Ugotovili smo, da so sistemi z 1,0 mg/L Bi(III) pri različnih potencialih elektronalaganja kinetično in difuzijsko kontrolirani procesi, sistemi z 0,5 mg/L Bi(III) so kinetično in difuzijsko kontrolirani pri potencialih, bolj negativnih od –0,6 V, pri potencialu elektronalaganja –0,6 V in bolj pozitivnih potencialih pa gre za kinetično kontrolirane procese. S SbFGCE smo v 0,01 M HCl določali Cd(II) in Pb(II), v 0,1 M acetatnem pufru pa zraven le teh še Zn(II). Z metodo EIS smo preučevali delovanje SbFGCE. Ugotovili smo, da na delovanje oziroma polarizacijsko upornost SbFGCE v acetatnem pufru koncentracija dodanih analitov nima signifikantnega vpliva pri vseh različnih potencialih EIS-analize in v HCl pri potencialih EIS-analize enakih potencialom elektronalaganja. Z uporabo EEC modelov smo ugotovili, da so pri najbolj negativnih potencialih elektronalaganja (–1,1 V za SbFGCE v HCl in –1,2 V za SbFGCE v acetatnem pufru) sistemi pod kinetično kontroliranimi procesi ne glede na prisotnost in koncentracijo analitov. Zaradi dobrih analitskih lastnosti BiFGCE in SbFGCE smo razvili nove elektrode z različnimi kombinacijami bizmutove in antimonove prevleke na GCE (BiSbFGCE) ter skupno masno koncentracijo Bi(III) in Sb(III) 0,5 mg/L ali 1,0 mg/L. 22 različnih metod smo delno validirali za določanje Zn(II), Cd(II) in Pb(II) v 0,1 M acetatnem pufru. Ugotovili smo, da imajo določene metode širše linearno območje in boljšo občutljivost za določanje analitov v primerjavi z drugimi kombiniranimi BiSbFGCE ali samo BiFGCE ali SbFGCE. Večina metod je za določanje Cd(II) in Pb(II) v okviru izbranih kriterijev točnosti in natančnosti. Potem smo optimizirali še čas elektronalaganja prevleke na GCE in ponovno delno validirali izbrane metode z optimiziranim časom elektronalaganja. Z optimizacijo smo dosegli nižje meje zaznavnosti in določljivosti ter boljšo občutljivost za določanje analitov. Na GCE smo razvili tudi nov senzor za detekcijo vodikovega peroksida. Gre za nov pristop priprave tovrstnega senzorja. Na GCE smo nanesli nov material iz nanodelcev grafena (GNP) brez uporabe encimov. Z amperometrično analizo pripravljenega senzorja smo potrdili, da je redukcija H2O2 difuzijsko kontroliran proces in da je GNP/GCE selektivna za H2O2. In the doctoral dissertation new methods for trace heavy metal detection are presented. In the last decade bismuth and antimony electrodes as an alternative to mercury electrode were presented, but the mechanism and working of these electrodes was not yet explained. In the doctoral thesis, a study of electrode behavior under various electroanalysis conditions by electrochemical impedance spectroscopy (EIS) is presented. An unmodified glassy carbon electrode (GCE) and in situ modified glassy carbon electrodes (bismuth modified BiFGCE or antimony modified SbFGCE) for Zn(II), Cd(II) and Pb(II) determination were used. Before the EIS analysis the methods were partially validated (limit of detection, limit of quantification, linear concentration range, sensitivity, accuracy, precision). For BiFGCE preparation, two different Bi(III) concentrations 0.5 mg/L and 1.0 mg/L in an electrolyte of 0.1 M acetate buffer were used. For the SbFGCE preparation the Sb(III) concentration was 0.5 mg/L in the electrolyte of 0.1 M acetate buffer or 0.01 M HCl. By using EIS for BiFGCE at different potentials it was found, that the films on the GCE prepared at certain deposition potentials have the same behaviour in their natural state, therefore they are suitable for electroanalysis. Using the equivalent electrical circuit (EEC) models the parameters for descripting the working of BiFGCE are obtained. We found out, that various additions of heavy metals in the electrolyte solution do not have a significant effect on the BiFGCE behaviour or on the capacitance and resistance of BiFGCE. Different EEC were used for fitting the results of different systems. We found out, that the behaviour of BiFGCE for heavy metal determination at different electroanalysis conditions (e.g. different deposition potentials) is not the same process. The systems with 1.0 mg/L Bi(III) at different deposition potentials are kinetic and diffusion-controlled processes and systems with 0.5 mg/L Bi(III) are kinetic and diffusion-controlled at potentials more negative than –0.6 V and only kinetic-controlled processes at deposition potential –0.6 V and more positive potentials. SbFGCE was used for Cd(II) and Pb(II) determination in 0.01 M HCl and also Zn(II) in 0.1 M acetate buffer. The behaviour of SbFGCE was studied using EIS. It was found out, that the concentration of analytes does not affect the resistance of SbFGCE in acetate buffer at different EIS potentials and in HCl at EIS potentials that are the same as deposition potentials. Using EEC we found out that the systems are under kinetic-controlled processes regardless of the presence and concentration of analytes at the most negative deposition potentials (–1.1 V for SbFGCE in HCl and –1.2 V for SbFGCE in acetate buffer). Due to the good analytical performances of BiFGCE and SbFGCE new electrodes, modified with combinations of bismuth and antimony film on GCE (BiSbFGCE) were developed. The total mass concentration of Bi(III) and Sb(III) in different films was 0.5 mg/L or 1.0 mg/L. 22 different methods were partially validated for Zn(II), Cd(II) and Pb(II) determination in 0.1 M acetate buffer. It was found that certain methods have wider linear concentration range and better sensitivity for analytes determination compared with other combined BiSbFGCE or pure BiFGCE or pure SbFGCE. Most of the developed methods for Cd(II) and Pb(II) determination are within the desired criteria for accuracy and precision. The deposition time was optimized and the certain methods were partially validated with the optimized deposition time. With deposition time optimisation lower limits of detection and quantification and better sensitivity were achieved. On GCE substrat a new non-encimatic sensor for hydrogen peroxide detection was developed. This is a new approach to prepare such sensor. A new material from graphene nanoparticles (GNP) was applied on the GCE surface. It was confirmed that the GNP/GCE is selective for H2O2.

V diplomski nalogi sem spremljala vpliv različnih organskih kislin na stabilnost vodne raztopine vodikovega peroksida v daljšem časovnem obdobju. Spreminjanje koncentracije raztopine vodikovega peroksida sem spremljala s pomočjo jodometrične titracije. Cilj naloge je bil ugotoviti, katere od izbranih organskih kislin najbolje stabilizirajo raztopino vodikovega peroksida. Svoje ugotovitve sem zbrala v tabelah in prikazala grafično. Eksperimentalni del je zajemal tudi pripravo in standardizacijo uporabljenih kemikalij. In this work the influence of different organic acids on the stability of hydrogen peroxide solution was studied. The changes in the concentration of the hydrogen peroxide solution were followed with iodometric titration. The aim of the work was to determine which of the selected organic acids posses the best stabilizing influence on the hydrogen peroxide solution. The results of the study are presented in tables and graphically. The experimental part also includes the preparation and standardization of the applied chemicals.

Namen diplomskega dela je bil ugotoviti, ali izbrana eterična olja (EO) delujejo protiglivno. Zato smo jim določili minimalno inhibitorno koncentracijo (MIC) ter minimalno mikrobicidno koncentracijo (MBC) ter njihovo delovanje primerjali z že uveljavljenim razkužilom – vodikovim peroksidom. Testirali smo EO origana (Origanum vulgare), grške bazilike (Ocimum basilicum), sladkega pelina (Artemisia annua), sivke (Lavandula hybrida), laškega smilja (Helichrysum italicum), rožmarina (Rosmarinus officinalis), nemške kamilice (Matricaria recutita) in žajblja (Salvia officinalis) ter vodikov peroksid s kvasovkami vrste Candida albicans in plesnimi vrste Penicillium griseofulvum. Za testiranje protiglivne aktivnosti smo uporabili metodo razredčevanja v mikrotitrski ploščici. Natančne vrednosti MIC in MBC smo za kvasovke določili z metodo štetja kolonij na trdnem gojišču, za plesni pa s pregledovanjem gojišča s plesnimi v mikrotitrskih ploščicah pod lupo. Kvasovke vrste C. albicans so bile bolj dovzetne za EO kot plesni vrste P. griseofulvum. Kvasovkam smo vrednosti MIC določili v območju

Industrija je največji porabnik vode in hkrati največji proizvajalec odpadnih vod. Odpadne vode iz industrije vsebujejo kompleksne snovi, ki jih v konvencionalnih čistilnih napravah ni mogoče odstraniti. Za potrebe odstranjevanja takšnih snovi se razvijajo naprednejši postopki čiščenja. V diplomski nalogi smo se osredotočili na čiščenje obarvanih odpadnih vod v tekstilni industriji. Za razbarvanje teh smo uporabili napredni oksidacijski postopek (AOP) H_2 O_2/UV. Izbrali smo tri barvila, ki se pogosto uporabljajo v tekstilni industriji, in sicer C. I. Acid Red 374, C. I. Reactive Black 5 in C. I. Direct Red 80. Proučili smo vpliv moči UV-sevanja na samo hitrost in učinkovitost razgradnje barvil ter spremljali spremembe parametrov onesnaženja. Industry is the largest water consumer and, at the same time, largest producer of wastewaters. Wastewaters from industry contains complex substances which cannot be removed in conventional wastewater treatment plants. For the purpose of removing such substances, advanced cleaning processes are being developed. In this thesis we have focused on treatment of colored wastewaters from textile industry. For decolorization we used advanced oxidation processes (AOP), specifically H_2 O_2/UV. We selected three dyes that are commonly used in textile industry, i.e. C.I. Acid Red 374, C.I. Reactive Black 5 in C.I. Direct Red 80. We studied the influence of UV radiation on the speed and efficiency of degradation of dyes and the changes in ecological parameters.

U radu je ispitan utjecaj pranja s izbjeljivanjem s dva različita sredstva za bijeljenje: praškom za bijeljenje i vodikovim peroksidom na prethodno biopoliranu pamučnu denim tkaninu bojadisanu s indigo bojilom. Odjevni proizvodi od pamučne denim tkanine obojadisani indigo bojilom su prani uz dodatak enzima radi otklanjanja dlakavosti površine, odnosno biopolirani. Nakon toga je jedan dio obrađivan s praškastim sredstvom za bijeljenje u koncentraciji od 2,5 g/L u vremenima od 3 i 5 min na 50 óC, a drugi dio s vodikovim peroksidom u koncentraciji 2,5 g/L u vremenima od 5 i 10 min. Nakon obrada na uzorcima su provedena ispitivanja vlačne čvrstoće, čvrstoće u šavu, površinske mase, postojanosti obojenja na vodu, na kiselinu, lužinu, pranje i habanje. Pranje odjevnih predmeta s izbjeljivanjem provedeno primjenom dvaju sredstva za bijeljenje imalo je velik utjecaj na njihova fizikalna svojstva i postojanosti obojenja u odnosu na neobrađene predmete., This study shows the impact of bio polishing and bleach wash of two different bleaching agent one is bleaching powder and another is hydrogen peroxide on 100 % cotton denim dyed with indigo dye. Garments were washed with enzyme to remove hairiness . biopolished. Then garments were subjected to a bleach concentration with bleaching powder of 2.5 g/L for 3 and 5 minutes at 50 oC temperature and other were bleached with hydrogen peroxide of 2.5 g/L for 5 and 10 minutes. The physical and colour fastness properties were analyzed in before and after washing. The properties that were analyzed include tensile strength, seam strength, fabric weight, and colour fastness to water, acid, alkali, washing and rubbing. Bleach washed garments by two different bleaching agent exhibit a great influence on the physical and colour fastness properties than the unwashed garments.