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A comparison of Kaibel and Christiansen configuration of the dividing-wall column
No full textDestilacija je najzastupljeniji proces izdvajanja komponenti iz kapljevitih smjesa, koji se koristi u mnogim granama industrije. U današnje vrijeme, zbog ekoloških i ekonomskih razloga, nastoji se štedjeti energija na svakom koraku – pa tako i u procesu destilacije, koji je energetski vrlo intenzivan jer uključuje isparavanje velikih količina tvari. Jedan od načina povećanja energetske učinkovitosti je primjena kolona s razdjelnom stijenkom (KRS), koje omogućuju izvođenje čitavog niza destilacijskih kolona unutar jednog plašta, uz značajne uštede kapitalnih i pogonskih troškova. Jedna od mogućih izvedbi KRS-a za četiri proizvoda je tzv. Kaibelova kolona, koja je nešto jednostavnije konstrukcije, ali i niže energetske učinkovitosti. Kaibelovu kolonu karakterizira osjetljivost kvalitete bočnih proizvoda na raspodjelu pare ispod razdjelne stijenke. Jedan od mogućih načina da se ta osjetljivost smanji, a time i poveća upravljivost, jest zamjena sekcije s kontaktnim tijelima između dvaju bočnih proizvoda izmjenjivačem topline, čime se onemogućuje ponovno miješanje ključnih komponenti srednjeg vrelišta. Takva izvedba naziva se Christiansenovom kolonom. Cilj ovog rada je usporedba dviju izvedbi – Kaibelove i Christiansenove KRS – za separaciju višekomponentne smjese aromatskih ugljikovodika na četiri proizvoda.Distillation is the most widely used process for separating components from liquid mixtures, employed across many branches of industry. Nowadays, due to both environmental and economic considerations, energy savings are sought at every step – distillation included, as it is highly energy-intensive owing to the evaporation of large quantities of material. Energy efficiency of distillation sequences can be enhanced through the use of dividing wall columns (DWC), which allow multiple distillation columns to operate within a single shell, resulting in significant savings in capital and operating costs. One possible DWC configuration for producing four product streams is the Kaibel column, which features a somewhat simpler design, but lower energy efficiency. A characteristic of the Kaibel column is the sensitivity of the side product quality to the vapor split beneath the dividing wall. One way to reduce this sensitivity, and thereby improve controllability, is to replace the section of the column containing internals between the two side products with a heat exchanger, which prevents remixing of the key intermediate-boiling components. This configuration is known as the Christiansen column. The aim of this work is to compare the two configurations – the Kaibel and Christiansen DWCs – for the separation of a multicomponent mixture of aromatic hydrocarbons into four product streams
Photocatalytic activity of strontium titanate
No full textStroncijev titanat (SrTiO3) je materijal poznat po svojim fotokatalitičkim svojstvima i mogućnostima primjene u procesima razgradnje organskih bojila. Organske boje, poput rodamina B (RhB), predstavljaju ekološki izazov zbog svoje stabilnosti, a njihovo uklanjanje iz okoliša zahtijeva učinkovite metode poput heterogene fotokatalize. U ovom radu istražena je fotokatalitička aktivnost SrTiO3 sintetiziranog različitim postupcima: Pechinijevim postupkom, limunskim postupkom i hidrotermalnim postupkom. Karakterizacija uzoraka provedena je tehnikama rendgenske difrakcije (XRD), infracrvene spektroskopije s Fourierovom transformacijom (FTIR) i UV-Vis difuzijske refleksijske spektroskopije (UV-Vis DRS). Fotokatalitička ispitivanja provedena su pod UV-C svjetlom, a rezultati su pokazali da je uzorak dobiven limunskim postupkom imao najbolju fotokatalitičku učinkovitost, dok je hidrotermalni postupak rezultirao najmanjom aktivnošću. Ova istraživanja potvrđuju da izbor metode sinteze značajno utječe na fotokatalitičku učinkovitost SrTiO3 te da razvoj učinkovitijih postupaka može poboljšati njegovu primjenu u sustavima za pročišćavanje vode i zraka.Strontium titanate (SrTiO3) is a material recognized for its photocatalytic properties and potential applications in the degradation of organic dyes. Organic dyes, such as rhodamine B (RhB), present an environmental challenge due to their stability, making their removal from water systems crucial. Heterogeneous photocatalysis is an effective methods for their degradation. This study examines the photocatalytic activity of SrTiO3 synthesized using different approaches: the Pechini process, citric process, and the hydrothermal process. The synthesized samples were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Photocatalytic performance was evaluated under UV-C light, and results indicated that the sample obtained via citric process exhibited the highest photocatalytic efficiency, while the hydrothermal process resulted in the lowest activity. These findings highlight the impact of synthesis methods on the photocatalytic effectiveness of SrTiO3 and emphasize the importance of process optimization for improved environmental applications
Interakcije mikroplastike i organskih onečišćivala u vodi
No full textNowadays, microplastics (MPs), plastic particles smaller than 5 mm, are a hot topic in the field of environmental science due to their abundance and widespread in the environment and the food chain, including the human organism. The greatest concern is the potential harmful and toxic effect MPs can have on both the environment and human health. Additionally, MPs can adsorb and transport other pollutants, possibly increasing overall toxicity compared to the toxicity of isolated MPs and pollutants. Hence, it is important to understand the adsorption process to properly assess the potential risk of MPs. Experimental results show that adsorption is mainly governed by weak hydrophobic, electrostatic, van der Waals and π-π interactions, and hydrogen bonds. However, due to system complexity and many influencing factors, the results often lack consistency and reproducibility, which makes it impossible to draw clear conclusions and build a predictive model for MPs adsorption. The computational chemistry studies on the adsorption of MPs are still at the early stages, but they are believed to provide further insights into the adsorption mechanism. In this thesis, polyethylene terephthalate (PET) MPs was chosen as one of the most frequently found types of MPs in the environment. Adsorption was studied using quantum mechanical (QM) and molecular dynamics (MD) methods. QM study revealed that the interactions are weak and local, mainly dependent on the pollutants ability to form multiple contacts with MPs. Further quantitative structure activity/property relationship (QSA/PR) modelling showed that the key pollutant properties governing the adsorption can be correlated to the size of pollutants and the number of proton donor/acceptor functional groups. On the other hand, MD study showed that, when the explicit water molecules are included, the adsorption is mainly controlled by the pollutant relative affinity for water and MPs. Additionally, the affinity also depends on the structure of MPs, as the aggregated PET model, made of thirty 5-mer, showed stronger capacity compared to the PET model made of one 150- mer chain. MD results showed similar trend as the experimental results. However, the difference in calculated interaction energies could not be quantitatively correlated with the difference in adsorption capacities. Overall, computational studies showed a great potential as a tool to help to understand adsorption mechanism, although more work is needed to further develop the model’s accuracy.Mikroplastika (MP) su čestice polimera manje od 5 mm koje su danas vrlo popularna tema u istraživanju okoliša zbog velike količine i rasprostranjenosti u okolišu i hranidbenom lancu, čak i u ljudskom organizmu. MP može imati štetne i toksične učinke na okoliš i ljudsko zdravlje. Osim toga, MP može adsorbirati i prenositi druga štetna onečišćivala što može dovesti do povećanja njihove ukupne toksičnosti u odnosu na toksičnost same MP i onečišćivala. Upravo iz tog razloga, važno je detaljno proučiti proces adsorpcije kako bi se moglo preciznije procijeniti potencijalne rizike povezane s MP. Dosadašnja eksperimentalna istraživanja pokazala su da adsorpciju organskih onečišćivala na MP kontroliraju slabe interakcije poput hidrofobnih, elektrostatskih, van der Waalsovih, π-π interakcija i vodikovih veza. S obzirom na složenost sustava i veliki broj čimbenika koji utječu na adsorpciju, rezultati iz literature često su nedosljedni te nisu reproducibilni. To otežava donošenje zaključaka i izradu pouzdanih predikcijskih modela za adsorpciju organskih onečišćivala na MP. Metode računalne kemije omogućuju dublje razumijevanje mehanizma adsorpcije te se sve više počinju koristiti u ovom području istraživanja. U okviru ovog rada, odabran je poli(etilen-tereftalat) (PET), kao jedan od najčešćih tipova MP u okolišu. Za istraživanje su korištene kvantno-mehaničke (QM, engl. quantum mechanics) i metode molekulske dinamike (MD, engl. molecular dynamics). QM proračuni pokazali su da su interakcije između MP i onečišćivala slabe, lokalne interakcije te da adsorpcija ovisi o broju interakcija koje onečišćivalo može uspostaviti s MP. Modeliranjem odnosa strukture i aktivnosti/svojstva (QSA/PR, engl. quantitative structure activity/property relationship) utvrđeno je da su ključna svojstva onečišćivala koja kontroliraju adsorpciju povezana s veličinom molekule i brojem proton donora/akceptora. MD simulacije koje uključuju eksplicitne molekule vode pokazale su da adsorpcija značajno ovisi o razlici između afiniteta onečišćivala za molekule vode i za MP. Također, pokazale su da struktura MP ima značajnu ulogu s obzirom na to da je model PET-a sačinjen od 30 lanaca koji sadržavaju 5 monomera pokazao veću sposobnost adsorpcije od modela jednog lanca koji sadržava 150 monomera. Rezultati MD simulacija u skladu su s eksperimentalnim opažanjima, iako razlike u izračunatim energijama interakcije nisu bile u izravnoj kvantitativnoj korelaciji s razlikama u adsorpcijskom kapacitetu. Zaključno, računalne metode pokazuju velik potencijal u istraživanju adsorpcijskih mehanizama MP, no potrebna su dodatna istraživanja i razvoj modela kako bi se povećala njihova točnost i primjenjivost
Synthesis, optimization of reaction conditions and structural characterization of novel acrylonitrile derived benzoxazoles prepared by green chemistry methods
No full textDerivati 2-cijanometilbenzoksazola i akrilonitrilni derivati benzoksazola važna su skupina heterocikličkih spojeva koji pokazuju široki spektar biološkog djelovanja. U ovom radu opisana je sinteza i strukturna karakterizacija 2-cijanometilnih i akrilonitrilnih derivata benzoksazola. Ciljani spojeva priređeni su klasičnim reakcijama organske sinteze i sinteze potpomognute mikrovalnim zračenjem. U prvom koraku sinteze, nukleofilnim napadom malononitrila 1 priređen je etil-2-cijanoacetamidat-hidroklorid 2. Konvencionalnim i zelenim metodama ciklizacije iz spoja 2 i odgovarajućih različito supstituiranih aminofenola 3, 6 i 8 priređeni su glavni prekursori, 2-cijanometilbenzoksazoli 4, 7 i 9. Reakcijom Knoevenagelove kondenzacije iz glavnih prekursora 4, 7 i 9 te odgovarajućih aromatskih aldehida 10-15 i 34-41 priređeni su akrilonitrilni derivati benzoksazola 16-27, 42, 43 i 46-49. Akrilonitrilni derivati benzoksazola 28-30, 44 i 45 nisu uspješno priređeni korištenom metodom te je metodu potrebno dodatno optimirati. Spojevi 31-33 dobiveni su kao smjese E- i Z-izomera. Strukture novopriređenih spojeva potvrđene su 1H i 13C NMR spektroskopijom, kao i
MS spektrometrijom.2-cyanomethylbenzoxazole derivatives and acrylonitrile derived benzoxazoles are an important group of heterocyclic compounds since they exhibit a broad spectrum of biological activities. This work describes the synthesis and structural characterization of 2-cyanomethyl and novel acrylonitrile derived benzoxazoles. The target compounds were prepared by using the standard reactions of organic synthesis and microwave-assisted synthesis. In the first step of the synthesis, ethyl-2-cyanoacetamidate hydrochloride 2 was prepared by nucleophilic reaction of malononitrile 1. The main precursors, 2-cyanomethylbenzoxazoles 4, 7 i 9 were prepared conventional and green synthetic methods, from compounds 3, 6 and 8 in the reaction cyclization with compounds 2. Acrylonitrile derived benzoxazoles 16-27, 42, 43 and 46-49 were prepared in the Knoevenagel condensation from the main precursors 4, 7 and 9 and the corresponding aromatic aldehydes 10-15 and 34-41. Acrylonitriles 28-30, 44 and 45 were not successfully prepared and the method should be further optimized. Compound 31-33 were found to exist as a mixture of E- and Z-isomers. The structures of the newly prepared compounds were confirmed by 1H and 13C NMR spectroscopy as well as by MS spectrometry
Optimization of polyhydroxyalkanoate production from waste biomass
No full textPlastika nastala iz nafte i naftnih derivata danas je jedan od najkorištenijih materijala u svakodnevnom životu ljudi. Međutim, uslijed njene sve veće proizvodnje, javlja se problem njene toksičnosti, adekvatnog odlaganja i akumulacije u okolišu. Iz tog razloga istražuju se nove vrste biorazgradive plastike s ciljem zamjene za sintetičku. Jedna od biorazgradivih vrsta plastike jesu polihidroksialkanoati, PHA. PHA su specifični zbog načina njihove sinteze i potpuno biorazgradive prirode. Naime, PHA se mogu proizvesti jedino metaboličkim procesima mikroorganizama. Ukoliko se mikroorganizmima pruži supstrat s manjkom dušika i velikim viškom ugljika, mikroorganizmi će početi proizvoditi PHA kao rezervni izvor energije. Kao potencijalni supstrat koji bi se mogao koristiti u te svrhe, u posljednje vrijeme sagledava se agroindustrijski otpad. Korištenjem agroindustrijskog otpada za proizvodnju PHA smanjila bi se količina samog otpada, a ujedno bi se proizveo novi i održivi materijal. Takav proces bi se potencijalno mogao implementirati u industrijske procese, čime bi se zadovoljili zahtjevi kružne ekonomije, a ujedno bi se povoljno utjecalo na okoliš. Međutim, agroindustrijski otpad zahtjeva adekvatnu predobradu kako bi postao povoljan supstrat za proizvodnju PHA.
U ovom radu ispitala se predobrada otpadnog škroba ultrazvukom, mijenjajući tri čimbenika, a to su vrijeme, jačina ultrazvuka i koncentracija otopine NaOH. Iz škroba su izolirane
4 bakterije: Leukonostoc sp., Citrobacter freundii, Staphilococcus lentus i Bacillus licheniformis te 3 gljive: Cryptococcus humicola, Geotrichum klebahnii i Candida krusei sa sposobnošću proizvodnje PHA. Isti su mikroorganizmi korišteni u procesu fermentacije na čvrstom nosaču (eng. Solid State Fermentation, SSF) kako bi se proizveo PHA. Rezultati su pokazali vrijednosti akumulacije PHA ne veće od 1 %, među kojima je najveća vrijednost 0,5572 % pri uvjetima predobrade škroba od 30 minuta, 2 W mL^-1 te koncentraciji NaOH od
0,01 mol L^-1. Generalno, što su uvjeti predobrade škroba bili većih vrijednosti (dulje vrijeme predobrade, veća jačina ultrazvuka te veća koncentracija otopine NaOH), to je akumulacija PHA bila manja. Infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR), diferencijalnom pretražnom kalorimetrijom (DSC) te termogravimetrijskom analizom (TGA) utvrđeno je kako bi se potencijalno moglo raditi o PHB i PHV homopolimerima te kopolimerima PHBV s različitim udjelima HB i HV te kopolimerima s raznim kratkolančanim i srednjelančanim PHA.Nowadays, plastic made from oil and oil derivatives is one of the most used materials in people's daily lives. However, due to its increasing production, a problem of its toxicity, adequate disposal and accumulation in the environment is arising. For this reason, scientific research is aimed towards new types of biodegradable plastics in order to replace the synthetic ones. One of the biodegradable types are polyhydroxyalkanoates, PHA. PHAs are specific because of their synthesis method and their completely biodegradable nature.
They can only be produced by metabolic processes of microorganisms. If microorganisms are provided with a substrate with nitrogen deficiency and a large excess of carbon, the microorganisms will start producing PHA as a reserve energy source. Recently,
agro-industrial waste has been considered as a potential substrate that could be used for these purposes. By using agro-industrial waste to produce PHA, the amount of waste itself would be reduced, and at the same time a new and sustainable material would be produced. Such process could potentially be implemented in industrial infrastructure, which could meet the requirements of the circular economy, whilst at the same time have a favorable impact on the environment. However, agro-industrial waste requires adequate pretreatment in order to become a favorable substrate for PHA production. In this paper, an ultrasound pretreatment of waste starch was examined by changing three factors, the time of ultrasonic treatment, the ultrasonic power and the concentration of the NaOH solution. Four bacteria were isolated from starch: Leukonostoc sp., Citrobacter freundii, Staphilococcus lentus and Bacillus licheniformis and three fungi: Cryptococcus humicola, Geotrichum klebahnii and Candida krusei. All of them can produce PHA. The same microorganisms were used in the solid-state fermentation process, SSF, to produce PHA. The results showed values of PHA accumulation not higher than 1%, among which the highest value was 0,5572% under starch pretreatment conditions of 30 minutes, 2 W mL^-1 and 0,01 mol L^-1. In general, results have shown that stronger starch pretreatment conditions (longer pretreatment, higher ultrasound power and higher concentration of NaOH solution) result with lower PHA accumulation. Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) showed that synthesized PHA polymers could potentially be PHB and PHV homopolymers, PHBV copolymers with different HB and HV proportions or copolymers made of various short-chain-length and medium-chain-length PHAs
Determination of the ecotoxicity of SARS-CoV-2 antivirals
No full textKoronavirus, bolest uzrokovana SARS-CoV-2 virusom koja primarno napada dišne puteve je uzrok smrti više od 7 milijuna ljudi širom svijeta. Iako su antivirusni lijekovi ključni za liječenje mnogih bolesti, mogu imati štetne učinke na vodene organizme. U sklopu ovog rada ispitao se utjecaj antivirusnih lijekova protiv SARS-CoV-2 virusa na bakteriju Pseudomonas putida i mikroalgu Chlorella sp. U eksperimentu s bakterijom Pseudomonas putida, bakterijske suspenzije bile su izložene različitim koncentracijama ribavirina, emtricitabina, sofosbuvira, oseltamivira, nirmatrelvira i atazanavira. Ispitivane koncentracije bile su za ribavirin, emtricitabin, sofosbuvir, oseltamivir i nirmatrelvir: 0,006 mmol/L, 0,013 mmol/L, 0,025 mmol/L, 0,05 mmol/L i 0,1 mmol/L, te atazanavir: 0,00019 mmol/L, 0,00038 mmol/L, 0,00075 mmol/L, 0,0015 mmol/L i 0,0030 mmol/L. Nakon 16 sati, određivao se ukupni broj živih stanica bakterija (CFU) kako bi se procijenilo koliko je svaki od antivirotika inhibirao rast bakterija. Rezultati su pokazali da su veće koncentracije antivirusnih lijekova rezultirale većom inhibicijom bakterija. Emtricitabin je bio najtoksičniji pri 0,1 mmol/L, inhibirajući rast bakterija za 98,94%, dok je oseltamivir bio najmanje toksičan, inhibirajući rast za 30,59 % pri
0,1 mmol/L i nije pokazao inhibiciju pri nižim koncentracijama. Eksperiment s mikroalgom Chlorella sp. se provodio na sličan način gdje su suspenzije mikroalge dodane u otopine s istim antivirusnim koncentracijama kao u eksperimentu s bakterijom. Ukupni broj živih stanica mikroalge (CFU) se određivao uz pomoć Thoma-ove komore svakih 24 sata tijekom tri dana, te je za konačni CFU uzeta srednja vrijednost. Slično rezultatima s bakterijom, veće koncentracije antivirusnih lijekova dovele su do značajnije inhibicije rasta mikroalge. Atazanavir pri 0,003 mmol/L bio je najtoksičniji, inhibirajući rast mikroalge za 58,52%, dok je nirmatrelvir bio najmanje toksičan, inhibirajući rast za 48,15% pri 0,1 mmol/L.Coronavirus, caused by the SARS-CoV-2 virus, targets the respiratory tract and has led to over 7 million deaths globally. While antivirals are crucial for treating many diseases, they can have detrimental effects on aquatic organisms. This study explored the impact of
SARS-CoV-2 antivirals on the bacterium Pseudomonas putida and the microalgae
Chlorella sp. In the experiment involving Pseudomonas putida, bacterial suspensions were exposed to varying concentrations of ribavirin, emtricitabine, sofosbuvir, oseltamivir, nirmatrelvir, and atazanavir. The antiviral concentrations were: ribavirin, emtricitabine, sofosbuvir, oseltamivir, and nirmatrelvir at 0.006 mmol/L, 0.013 mmol/L, 0.025 mmol/L,
0.05 mmol/L, and 0.1 mmol/L, respectively, and atazanavir at 0.00019 mmol/L,
0.00038 mmol/L, 0.00076 mmol/L, 0.0015 mmol/L, and 0.0030 mmol/L. After 16 hours, the colony-forming units (CFU) were counted to assess bacterial viability. The results indicated that higher antiviral concentrations resulted in greater bacterial inhibition. Emtricitabine was the most toxic at 0.1 mmol/L, inhibiting bacterial growth by 98.94%, while oseltamivir was the least toxic, inhibiting growth by 30.59% at 0.1 mmol/L and showing no inhibition at lower concentrations. The experiment with Chlorella sp. followed a similar protocol. Microalgae suspensions were added to solutions with the same antiviral concentrations as the bacterial experiment. Live cell counts were performed using a Thoma's chamber every 24 hours over three days, and the average CFU was calculated. Similar to the bacterial results, higher antiviral concentrations led to more significant inhibition of microalgae growth. Atazanavir at 0.003 mmol/L was the most toxic, reducing microalgae growth by 58.52%, while nirmatrelvir was the least toxic, inhibiting growth by 48.15% at 0.1 mmol/L
Electrochemical synthesis of WO3/BiVO4 photoanode for amoxicillin degradation
No full textCilj ovog rada bio je prirediti i karakterizirati elektrode WO3 i WO3 - BiVO4 te ih ispitati u fotoelektrokemijskom proces razgradnje 0,1 mmol/dm^3 amoksicilina. Elektrode su se okarakterizirale metodama linearne polarizacije, kronoamperometrije, OCP, elektrokemijske impedancije i Mott - Schottky. Sve metode su provedene u uvjetima osvijetljenosti i neosvijetljenosti, a kao izvor svijetla služila je LED lampa. Fotoelektrokemijski proces razgradnje amoksicilina pratio se metodom kronoamperometrije. Tijekom ovog procesa uzimali su se uzorci u razmacima od pola sata kako bi se promjena koncentracije pratila
UV/Vis spektrofotometrom. Iz rezultata se uočava kako dolazi do pojave fotostruja što ukazuje da dolazi do uspješnog stvaranja parova elektron - šupljina. Mjerenja su pokazala kako najbolja fotoelektrokemijska svojstva pokazuje elektroda s elektrodepozicijski nanesenim BiVO4 na sloj WO3. Tijekom fotoelektrokemijskog procesa dolazi do razgradnje amoksicilina što znači da su elektrode uspješno pripravljene.The aim of this work was to prepare and characterize WO3 and WO3 - BiVO4 electrodes and to test it in the photoelectrochemical process for degradation of 0.1 mmol/dm^3 amoxicillin. Methods used in this work were linear polarization, chronoamperometry, OCP, electrochemical impedance and Mott - Schottky. All methods were performed under light and dark conditions where the light source was a LED lamp. The photoelectrochemical process of amoxicillin degeadation was monitored using the chronoamperometry method. During this process, samples were taken at intervals of half an hour in order to monitor the change in amoxicillin concentration with an UV/Vis spectrophotometer. From the obtained results, it is evident that a photocurrent appears, which indicates that there is a successful formation of electron - hole pairs.
The investigations showed that the best photoelectrochemical properties are obtained for the electrode with BiVO4 electrodeposited on the surface of WO3 layer. During the photoelectrochemical process, the decomposition of amoxicillin was detected, which means that the electrodes have been successfully prepared
Preparation of polysaccharide-based scaffolds as drug carriers
No full textBioragradljive okosnice česta su tema današnjih istraživanja u području tkivnog inženjerstva i biomedicinske primjene. Uz svoja intrinzična svojstva biokompatibilnosti, biorazgradljivosti i netoksičnosti, pružaju optimalnu podlogu za daljnje modifikacije, bilo za svrhu obnove oštećenog tkiva, djelovanja kao privremene potpore ili čak lokalizirane dostave lijekova. Također, razni načini priprave samog materijala omogućuju stvaranje željene strukture koja je namijenjena za ciljanu svrhu. Cilj ovog rada je priprava kitozanskih okosnica modificiranih kalcij-fosfatnom keramikom (hidroksiapatitom) kao potencijalnih nosača antitumorskog lijeka (doksorubicina) uz istovremeno poticanje obnove tkiva Pripremljene su kompozitne okosnice s različitim udjelom hidroksiapatita (0, 10, 20 i 30%). Provedeni su postupci toplinski inducirane fazne separacije i liofilizacije za izradu okosnica. Time se omogućuje stvaranje poroznih struktura unutar samog materijala čime se povećava specifična površina okosnica. Dobivene strukture identificirane su i karakterizirane energijski razlučujućom rendgenskom spektroskopijom (eng. Energy-Dispersive X-ray Spectroscopy, EDS), pretražnom elektronskom mikroskopijom (eng. Scanning Electron Microscopy, SEM) i infracrvenom spektroskopijom s Fourierovom transformacijom (eng. Fourier Transform Infrared Spectroscopy, FTIR) što je ukazalo na ugradnju kalcij-fosfatne faze u polimernu matricu kitozana. Dodatno, pretražna elektronska mikroskopija je potvrdila poroznu strukturu okosnica s međusobno povezanim porama. Kapacitet apsorpcije vode okosnica istražen je u fosfatnom puferu tijekom 24 sata. Kompozitne okosnice pokazale su manji kapacitet apsorpcije vode nego okosnice čistog kitozana. Otpuštanje lijeka doksorubicina praćeno je u fosfatnom puferu koristeći fluorescencijsku metodu tijekom 24 sata. Utvrđeno je da sustavi s manjim udjelom hidroksiapatita pokazuju naglo početno otpuštanje lijeka.Biodegradable scaffolds are a frequent topic of today's research in the field of tissue engineering and biomedical applications. With their intrinsic properties of biocompatibility, biodegradability and non-toxicity, they provide an optimal basis for further modifications, either for the purpose of regenerating damaged tissue, acting as temporary support or even localized drug delivery. Also, different ways of preparing the material itself enable the creation of the desired structure that is intended for the target purpose. The aim of this work was to prepare the chitosan scaffolds modified with calcium-phosphate ceramics (hydroxyapatite) as potential carriers of an antitumor drug (doxorubicin) with simultaneous tissue regeneration. Composite scaffolds with different amounts of hydroxyapatite (0, 10, 20 and 30%) were prepared. The thermally induced phase separation and lyophilization were carried out for the production of scaffolds. This enables the creation of porous structures, which increases the specific surface area of the scaffolds. The resulting structures were identified and characterized by Energy-Dispersive X-ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) which indicated the incorporation of the calcium-phosphate phase into the polymer matrix. Additionally, SEM indicated the porous structure with interconnected pores. The water absorption capacity of the scaffolds was investigated in a phosphate buffer for 24 hours. Composite scaffolds showed lower absorption and swelling capacity than pure chitosan scaffolds. The release of the drug doxorubicin was monitored in a phosphate buffer using the fluorescence method for 24 hours. It was determined that the release of doxorubicin from composite scaffolds was initially higher for composite scaffolds with lower amounts of hydroxyapatite
The influence of sodium hypochlorite on the presence of xenobiotics in model and real wastewater
No full textPovećana upotreba antiparazitika u veterinarske i druge medicinske svrhe, te široka primjena pesticida u poljoprivredi, dovode do kontinuiranog i nekontroliranog ispuštanja ksenobiotika u okoliš. Iako se oni i njihovi razgradni i transformacijski produkti u okolišu nalaze u tragovima, mogu uzrokovati dugoročno visoku koncentraciju tih onečišćivala i tako štetno djelovati na okoliš. Prije ili kasnije ti spojevi ispiranjem ili otjecanjem voda dospijevaju u vodeni okoliš i otpadne vode. Brojna istraživanja pokazuju da je uklanjanje mnogih ksenobiotika u konvencionalnim uređajima za obradu otpadnih voda često nepotpuno te stoga dolazi do onečišćenja prirodnih vodotoka. Poznato je da sredstva za dezinfekciju također uklanjaju i organska onečišćenja stoga je cilj ovoga rada procijeniti utjecaj prisutnosti natrijevog hipoklorita kao dezinfekcijskog sredstva na uklanjanja ksenobitika u otpadnim vodama nakon postupka šaržne biorazgradnje kao konvencionalne i često primjenjivane metode. Provodio se proces biorazgradnje u tri aerirana šaržna reaktora različitih sadržaja. Prvi reaktor je sadržavao aktivni mulj i radnu otopinu ksenobiotika masene koncentracije
10 mg L^-1. Kao kontrolni reaktori, drugi reaktor je sadržavao samo aktivni mulj, dok je treći reaktor sadržavao samo radnu otopinu ispitivanog ksenobiotika iste koncentracije. Uz ispitivanje fizikalnokemijskih parametara biorazgradnje, praćena je koncentracija u vremenskim razmacima uzorkovanja. Nakon procesa biorazgradnje, otopine ksenobiotika podvrgnute su procesu fotolize kao obliku tercijarne obrade otpadnih voda. Fotoliza se provodila u četiri kvarcne posudice s različitim sadržajem. Tijekom procesa fotolize ispitivan je utjecaj prisutnosti natrijevog hipoklorita na uklanjanje ksenobiotika uz usporedno provođenje uklanjanja ksenobiotika s vodikovim peroksidom kao vrlo učinkovitom metodom. Rezultati su pokazali različit postotak uklanjanja šest ispitivanih ksenobiotika. Novonastali razgradni i/ili transformacijski produkti detektirani su tekućinskom kromatografijom visoke djelotvornosti. Također, procijenjena je toksičnost istraživanih otopina ksenobiotika pomoću bioluminiscentne metode određivanja akutne toksičnosti bakterijom Vibrio fischeri.The increased use of antiparasitics for veterinary and other medical purposes, and the widespread use of pesticides in agriculture, lead to the continuous and uncontrolled release of xenobiotics into the environment. Although they and their degradation and transformation products are found in traces in the environment, they can cause a long-term high concentration of these pollutants and thus have a harmful effect on the environment. Sooner or later, these compounds end up in the water environment and waste water through washing or runoff. Numerous studies show that the removal of many xenobiotics in conventional waste water treatment devices is often incomplete and therefore pollution of natural waterways occurs. It is known that disinfectants also remove organic pollutants, therefore the aim of this work is to evaluate the influence of the presence of sodium hypochlorite as a disinfectant on the removal of xenobiotics in wastewater after batch biodegradation as a conventional and often applied method. The biodegradation process was carried out in three aerated batch reactors with different contents. The first reactor contained activated sludge and a working solution of xenobiotics with a mass concentration of 10 mg L^-1. As control reactors, the second reactor contained only activated sludge, while the third reactor contained only the working solution of the tested xenobiotic of the same concentration. In addition to testing the physico-chemical parameters of biodegradation, the concentration was monitored at sampling intervals. After the biodegradation process, the xenobiotic solutions are subjected to the photolysis process as a form of tertiary wastewater treatment. Photolysis was carried out in four quartz vessels with different contents. During the photolysis process, the influence of the presence of sodium hypochlorite on the removal of xenobiotics was examined, with a comparative performance of xenobiotic removal with hydrogen peroxide as a very effective method. The results showed a different percentage of removal of the six tested xenobiotics. Newly formed degradation and/or transformation products were detected by high performance liquid chromatography. Also, the toxicity of the investigated solutions of xenobiotics was evaluated using the bioluminescent method of determining acute toxicity by the bacterium Vibrio fischeri
Investigation of significant factors for biodegradation of polystyrene and polyvinyl chloride using bacterial culture Bacillus licheniformis
No full textRastuća količina plastičnog otpada postala je ozbiljan okolišni i društveni problem. U skorije vrijeme pojavio se veliki problem malih dimenzija, mikroplastika (MP). MP su plastične čestice manje od 5 mm, a njihova je prisutnost danas zabilježena u svim sastavnicama okoliša. Bioakumulacijom u hranidbenom lancu vrlo brzo se mogu naći i u čovjekovom organizmu, gdje imaju visok potencijal štetnog djelovanja. Spomenute male dimenzije ovih čestica čine njihovo uklanjanje iz okoliša gotovo nemogućim zadatkom, stoga je bitno što prije razviti inovativni pristup zbrinjavanja ove vrste otpada. Kao jedno od ekološki prihvatljivih rješenja tog problema, javlja se biorazgradnja plastike koristeći mikroorganizme i njihov enzimski potencijal, čime se nudi mogućnost razvoja tehnologije biološke obrade plastičnog otpada. U ovom radu ispitali su se značajni čimbenici za proces biorazgradnje MP čestica, polistirena (PS) i poli(vinil-klorida) (PVC) primjenom bakterijske kulture Bacillus licheniformis. Eksperiment je osmišljen prema Taguchi dizajnu prema kojem je ispitano 7 čimbenika: temperatura, pH vrijednost, broj okretaja, veličina i koncentracija MP, optička gustoća i dodatak glukoze i to na 2 razine - minimalna i maksimalna vrijednost. Tijekom 30 dana praćena je promjena CFU vrijednosti, a u filtratu vodene faze određivane su vrijednosti ukupnog organskog ugljika (TOC) i anorganskog ugljika (IC). Nastali razgradni produkti i/ili otpušteni aditivi praćeni su LC-MS analizom, dok su strukturalne promjene okarakterizirane FTIR-ATR spektroskopijom. Nakon 30 dana provođenja procesa biorazgradnje ispitana je toksičnost filtrata na Vibrio fischeri. Značajni čimbenici određivani su statističkom analizom varijance (ANOVA) prema eksperimentalnim rezultatima. Rezultati ovog eksperimenta pokazali su prema CFU analizi da je B. licheniformis koristio PS i PVC kao izvor supstrata pri određenim uvjetima. LC-MS analizom potvrđena je prisutnost novih spojeva u vodenoj fazi, a FTIR-ATR spektroskopijom potvrđene su promjene u materijalu, što su potvrde uspješne biorazgradnje. Kao značajni čimbenik ovog procesa biorazgradnje pokazala se optička gustoća. Dakle, B. licheniformis ima sposobnost biorazgradnje PS i PVC čestica, ali je od velike važnosti odabrati optimalne uvjete za najveću učinkovitost.The growing amount of plastic waste has become a serious environmental and social issue. Recently, a major problem of small dimensions has emerged, microplastics (MP). MP are plastic particles smaller than 5 mm, and their presence is now found in all components of the environment. Due to bioaccumulation in the food chain, they can very quickly enter the human body, where they can have negative influence on human health. The aforementioned small size of these particles makes their removal from the environment almost impossible, which is why it is urgent to develop an innovative approach to the disposal of this type of waste. One of the environmentally friendly solutions to this problem is the biodegradation of plastics using microorganisms and their enzymatic potential, and it offers the possibility of developing a biological treatment technology for plastic waste. In this work, the significant factors for the process of biodegradation of MP particles of polystyrene (PS) and polyvinyl chloride (PVC) were studied using the bacterial species Bacillus licheniformis. The experiment was designed according to Taguchi design in which 7 factors were tested: temperature, pH, rpm, size and concentration of MP, optical density and addition of glucose, at 2 levels - minimum and maximum. During 30 days, the change in CFU value was monitored, and the values of total organic carbon (TOC) and inorganic carbon (IC) were determined in the filtrate of the aqueous phase. The formed degradation products or released additives were monitored by LC-MS analysis, while the structural changes were characterized by FTIR-ATR spectroscopy. After 30 days of biodegradation, the toxicity of the filtrate to Vibrio fischeri was tested. Significant factors were determined by statistical analysis of variance (ANOVA) according to the experimental results. According to CFU analysis, the results of this experiment showed that B. licheniformis used PS and PVC as substrate sources under certain conditions. The LC-MS analysis confirmed the presence of new compounds in the aqueous phase, and the FTIR-ATR spectroscopy confirmed changes in the material, confirming successful biodegradation. Optical density was found to be a significant factor in this biodegradation process. Thus, B. licheniformis is able to biodegrade PS and PVC particles, but it is of great importance to choose optimal conditions for the highest efficiency