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Characterization of autochthonous microorganisms with high ability to degrade hydrocarbons from oil contaminated soils
No full textKako potreba za naftom i njenim proizvodima raste, tako dolazi i do sve češćih onečišćenja okoliša prilikom raznih aktivnosti tijekom njezine uporabe. Zbog svog negativnog utjecaja na sav živi svijet, naftne ugljikovodike nužno je ukloniti iz okoliša. Jedan od postupaka za remedijaciju tla onečišćenog naftom je bioremedijacija. Bioremedijacija je okolišno i ekonomski prihvatljiv postupak za uklanjanje prisutnog onečišćenja u kojem mikroorganizmi i njihovi enzimi imaju ključnu ulogu. Kako bi se povećala učinkovitost bioremedijacije potrebno je selektirati mikroorganizme koji pokazuju afinitet za razgradnju naftnih ugljikovodika. U ovom radu provedena je izolacija, identifikacija i karakterizacija autohtonih mikrobnih kultura iz uzorka tla onečišćenog sirovom naftom u šaržnim uvjetima u periodu 28 dana. Dobivene vrijednosti CFU su se kretale u rangu od 1,20 × 10^7 do 1,15 × 10^9/g tla. Rezultati pokazuju da je aktivnost bakterija i gljiva bila najveća pri pH-vrijednosti 7,25 i 6,5. Na temelju morfologije, biokemijskih testova i MALDI TOF analize identificirane su bakterijske vrste: Bacillus megaterium, Bacillus licheniformis, Bacillus cereus i Pseudomonas chlororaphis.As the demand for petroleum and petroleum products increases, so does the pollution caused by the various activities associated with the use of petroleum. Because of their negative impact on all living things, petroleum hydrocarbons must be removed from the environment. One of the methods of remediation of oil polluted soil is bioremediation. Bioremediation is an ecologically and economically viable method of removing contaminated sites, in which microorganisms and their enzymes play a key role. In order to increase the efficiency of bioremediation, it is necessary to select microorganisms that have affinity for degradation of petroleum hydrocarbons. In this work, the isolation, identification and characterization of autochthonous microbial cultures from a petroleum contaminated soil sample was carried out under batch conditions over a period of 28 days. Determinated CFU values ranged from 1.20 × 10^7 to 1.15 × 10^9/g soil. The results show that the activity of bacteria and fungi was highest at pH 7.25 and 6.5. Based on morphology, biochemical tests and analysis of MALDI TOF, bacterial species were identified: Bacillus megaterium, Bacillus licheniformis, Bacillus cereus, and Pseudomonas chlororaphis
Synthesis of metal nanoparticles from metallosurfactants
No full textCilj ovog rada bio je istražiti sintezu metalnih nanočestica Co, Ni i Cu kemijskom redukcijom pomoću dimernih PAT koje u svojoj strukturi sadrže metale, (12–2–12)[MBr4], M = Co, Ni, Cu, u dva različita medija, u vodi i emulziji heksan/voda. Jedno od važnih svojstava PAT koje u svojoj strukturi sadrže metale je sposobnost asocijacije u različite molekulske asocijate kao što su npr. micele, koje mogu poslužiti i kao izvor metalnih iona i kao predložak za sintezu metalnih nanočestica. Sinteza metalnih nanočestica je već duže vrijeme u centru pažnje znanstvenika jer zahvaljujući svojim specifičnim fizikalno-kemijskim svojstvima pružaju široku mogućnost primjene u različitim granama industrije, medicine i farmacije. Jedna od najjednostavnijih metoda sinteze metalnih nanočestica je kemijska redukcija, no ona često zahtijeva upotrebu toksičnih kemikalija. Korištenjem PAT kao izvora nanočestica te istovremeno kao stabilizatora, smanjuje se potreba za dodatnim kemikalijama.
Za određivanje veličine i morfologije sintetiziranih metalnih nanočestica korištene su mikroskopske tehnike, pretražna elektronska mikroskopija (SEM) i transmisijska elektronska mikroskopija (TEM), a za utvrđivanje prisutnih kemijskih elemenata, energijski razlučujući spektrometar (EDS). Za određivanje veličine i ζ potencijala dobivenih nanočestica korišteno je dinamičko raspršenje svjetlosti (DLS) i elektroforetsko raspršenje svjetlosti (ELS). Utvrđeno je da sinteza iz vode, iako ekološki prihvatljivija, lošiji sintetski put u odnosu na emulzije heksan/voda. U svim pokušajima sinteze izolirane su nanočestice metalnih oksida što je vidljivo iz snimljenih EDS spektara. Pomoću TEM i DLS analiza pokazano je da su pojedinačne nanočestice jako male i odgovaraju otprilike veličini micela dimernih PAT, ali su sklone agregiranju usprkos relativno velikim ζ potencijalima.The aim of this study was to investigate the synthesis of Co, Ni, and Cu nanoparticles from dimeric surfactants (12–2–12)[MBr4], M = Co, Ni, Cu using chemical reduction method, in two different media: water and a hexane/water emulsion. An important property of dimeric surfactants containing metals is their ability to form metallomicelles, which can act both as a source of metal ions and as a template for the synthesis of metallic nanoparticles.
The synthesis of metallic nanoparticles has attracted considerable attention because of their distinctive physicochemical properties, which enable a broad spectrum of applications across diverse industries, particularly in medicine and pharmaceuticals. Chemical reduction is one of the simplest methods for synthesizing metallic nanoparticles, although it often requires toxic chemicals. By using dimeric surfactants as both a source of nanoparticles and as stabilizers, the need for additional chemicals is reduced. Microscopic techniques, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to determine the size and morphology of the synthesized metallic nanoparticles, while energy dispersive spectroscopy (EDS) was employed to identify the chemical elements present. Dynamic light scattering (DLS) and electrophoretic light scattering (ELS) were used to measure particle size and zeta potential. The findings indicate that while synthesis in water is more environmentally friendly, it is a less effective synthetic route compared to the hexane/water emulsion. In all synthesis attempts, metallic oxide nanoparticles were isolated, as shown by the recorded EDS spectra. TEM and DLS analyses revealed that individual nanoparticles were very small, approximately the size of the dimeric surfactant micelles, but they tended to aggregate despite relatively high zeta potentials
Electrochemical characterization of dimeric metallosurfactants
No full textPovršinski aktivne tvari, zahvaljujući svojim amfifilnim svojstvima, nalaze široku primjenu u različitim područjima, uključujući i elektrokemiju. U ovom radu provedena je elektrokemijska karakterizacija staklaste ugljikove elektrode (GC) u prisutnosti dimerne kationske površinski aktivne tvari (12-2-12) (PAT) te u prisutnosti PAT-a koji u protuionu sadrži različite prijelazne metale (12-2-12)[MBr4] pri čemu je M = Co, Ni, Zn, Cu (PAT M). Ispitivanja su provedena u otopini elektrolita, Na2SO4, pri koncentracijama ispod (PAT 1/PAT 1 M) i iznad (PAT 2/PAT 2 M) kritične micelizacijske koncentracije (cmc) korištenjem elektrokemijske impedancijske spektroskopije (EIS) i cikličke voltammetrije (CV). Rezultati su pokazali da dodatak PAT 1 u otopinu elektrolita ne uzrokuje značajne promjene u elektrokemijskom odzivu GC elektrode dok dodatak PAT 2 dovodi do povećanja kapaciteta elektrode. U prisutnosti PAT M spojeva (M = Co, Ni, Zn), osobito u koncentracijama iznad cmc-a (PAT 2 M), zabilježen je porast specifičnih struja i nastanak novih strujnih vrhova u CV-u GC elektrode, kao i složeniji odgovori u EIS-u (više od jedne vremenske konstante). To ukazuje na prisutnost dodatnih elektrokemijskih procesa osim čistog nabijanja/izbijanja električnog dvostrukog sloja. Najizraženiji efekti zabilježeni su u prisutnosti PAT-a koji sadrži Cu, osobito pri višoj koncentraciji (PAT 2 Cu). Voltamogrami i impedancijski spektri (IS) GC elektrode u tim slučajevima pokazuju značajne elektrokemijske promjene unutar ispitivanog sustava. One se manifestiraju kroz dodatne strujne vrhove u CV-u te kao dodatne vremenske konstante u IS-u ukazujući na postojanje brojnijih redoks procesa i kompleksniju elektrokemijsku dinamiku unutar ispitivanog sustava.Surfactants are widely used in many different areas, including electrochemistry owing to their amphiphilic properties. In this work, the electrochemical characterization of glassy carbon electrode (GC) was carried out in the presence of a dimeric surfactants (12-2-12) (PAT) and in the presence of PAT with modified transition metal counterion (12-2-12)[MBr4], i.e., M = Co, Ni, Zn, Cu (PAT M). The electrochemical behavior of GC was carried out in an electrolyte solution, Na2SO4, containing different concentrations of PAT/PAT M solutions: pre-micellar (PAT 1/PAT 1 M) and post-micellar (PAT 2/PAT 2 M). The electrochemical techniques used were electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The results showed that the addition of PAT 1 to the electrolyte solution does not lead to any significant changes in the electrochemical response of the GC electrode. On the other hand, the addition of PAT 2 leads to an increase in electrode capacity. In the presence of PAT M solutions (M = Co, Ni, Zn), an increase in the specific currents and the formation of new current peaks can easily be observed in the CV, while new time constants can be recognized in the impedance spectra (IS). This indicates that in addition to the pure charging/discharging of the electrical double layer, more complex electrochemical process are also taking place. These changes become even clearer when PAT 2 M is added to the electrolyte solution. The most pronounced effects in both CV and EIS were observed in the presence of PAT Cu, especially at post-micellar concentrations (PAT 2 Cu). In these cases, the voltamograms and IS of the GC electrode show clear electrochemical changes within the tested system. These are reflected in additional current peaks in the CVs and additional time constants in the IS, indicating additional redox processes and more complex electrochemical dynamics in the tested system
Distribution of organic pollutants in the air, total deposited matter, and soil in the city of Zagreb and its surroundings
No full textOnečišćenje zraka je globalni problem koji uzrokuje brojne posljedice po ljudsko zdravlje i okoliš. Dokazano štetne učinke imaju lebdeće čestice u zraku, osobito one ekvivalentnog aerodinamičkog promjera manjeg od 10 μm (PM10) i 2,5 μm (PM2,5), koje mogu u svom sastavu sadržavati brojne toksične tvari. Policiklički aromatski ugljikovodici (PAU) su spojevi od posebnog interesa zbog svog štetnog kancerogenog djelovanja, dok poliklorirani bifenili (PCB) i organoklorovi pesticidi (OCP) pripadaju grupi postojanih organskih onečišćujućih tvari koje karakterizira postojanost, bioakumulacija i toksičnost. Atmosfersko taloženje, uključujući suho i mokro taloženje, koje je ključno za uklanjanje onečišćujućih tvari iz zraka, može imati negativne učinke na ekosustave i posredno na ljudsko zdravlje. Štetni organski spojevi dospijevaju u tlo putem prirodnih procesa taloženja i ljudskom aktivnošću kao što je izlijevanje nafte, neodgovarajuće odlaganje otpada ili uslijed požara. U prvom dijelu istraživanja provedena su preliminarna ispitivanja koja su obuhvatila različite metode priprave uzoraka za određivanje PAU-a, PCB-a i OCP-a u lebdećim česticama u zraku, ukupnoj taložnoj tvari (UTT) i tlu. Postupci kojima je bilo moguće optimalno istovremeno odrediti spojeve iz sve tri grupe primijenjeni su na uzorke UTT-a, frakcije lebdećih čestica PM10 i tla s različitih lokacija u Gradu Zagrebu i okolici. Tijekom tri godine (2020. – 2023. godina) kontinuirano su sakupljani mjesečni uzorci UTT-a na deset lokacija, a tjedni uzorci frakcije lebdećih čestica PM10 sakupljani su na jednom mjernom mjestu tijekom 2022. godine. Kompozitni uzorci površinskog sloja tla uzeti su na istim lokacijama 2022. godine te je provedena fizikalno-kemijska karakterizacija tla i određen sadržaj elemenata. Pronađene su razlike u tokovima taloženja PAU-a između mjernih mjesta, ali su se pokazale statistički značajne samo za PAU-e s četiri aromatska prstena i benzo[a]piren u UTT-u na nekim mjernim mjestima. Za PCB-e i OCP-e u UTT-u nije pronađena statistički značajna razlika između mjernih mjesta. Značajne sezonske razlike u tokovima taloženja uočene su za PAU-e, pojedine heksa- i hepta-PCB-e te izomere HCH, pri čemu su najviše vrijednosti zabilježene zimi. Masene koncentracije spojeva PAU, HCH, DDT i njegovih razgradnih produkata u frakciji lebdećih čestica PM10 bile su značajno više zimi, dok se kod PCB-a sezonski minimum i maksimum razlikovao ovisno o stupnju kloriranja kongenera. Dijagnostički omjeri PAU-a i rezultati faktorske i rojne analize te analize glavnih komponenti, pokazuju prisutnost različitih izvora onečišćenja, ovisno o mjernom mjestu i godišnjem dobu (izgaranje biomase, nafte i fosilnih goriva, emisije iz prometa), dok se prisutnost PCB-a i OCP-a povezuje s povijesnim ili prekograničnim unosima. Primijenjeni statistički alati upućuju na kompleksne međusobne odnose između spojeva te su različito grupirali mjerna mjesta, ovisno o promatranoj sastavnici okoliša. Uz karakter mjernog mjesta i lokalne izvore, na razine PAU-a, PCB-a i OCP-a utječe i sam geografski položaj mjernog mjesta, što je vjerojatno povezano s različitim režimom oborina i strujanja zraka. Značajne linearne korelacije između PAU-a u UTT-u i frakciji lebdećih čestica PM10 te između PCB-a s višim stupnjem kloriranja u UTT-u i frakciji lebdećih čestica PM10 upućuju na zaključak da suho taloženje vjerojatno ima značajnu ulogu u uklanjanju tih spojeva iz atmosfere. Odnosi između pojedinih PAU-a, PCB-a i OCP-a u tlu i UTT-u ukazuju na složene mehanizme kruženja tih spojeva u okolišu.Air pollution is a global issue that leads to various negative outcomes to human health and the environment. Particulate matter in the air, especially that with an equivalent aerodynamic diameter of less than 10 μm (PM10) and 2.5 μm (PM2.5), has been proven to have harmful effects and can contain various toxic substances. Polycyclic aromatic hydrocarbons (PAHs) are compounds of particular interest due to their harmful carcinogenic effects, while polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) belong to the group of persistent organic pollutants characterized by persistence, bioaccumulation, and toxicity. Atmospheric deposition, including dry and wet deposition, is crucial for removing pollutants from the air, but it can have negative effects on ecosystems and, indirectly, on human health. Harmful organic compounds enter the soil through natural deposition processes, as well as due to local events such as oil spills, improper waste disposal, and fires. In the first part of this study, preliminary investigations were conducted, covering various sample preparation methods for determining PAHs, PCBs, and OCPs in particulate matter, total deposited matter (TDM), and soil. Procedures that showed optimal results for the simultaneous determination of all three groups of compounds were selected. The optimized methods were applied to samples of PM10, TDM, and soil at various polluted locations in the city of Zagreb and its surroundings. Over three years (2020–2023), monthly TDM samples were continuously collected at ten locations, and weekly samples of the PM10 fraction of airborne particles were collected at one measurement site in 2022. Additionally, composite samples of the surface soil layer were collected at the same locations in 2022, and the physical and chemical characteristics of the soil and the elements present were determined. Differences in PAHs deposition fluxes between measurement sites were found, but were statistically significant only for PAHs with 4 aromatic rings and benzo[a]pyrene in TDM at some locations.
No statistically significant difference between locations was found for PCBs and OCPs in TDM. Significant seasonal differences in deposition fluxes were observed for PAHs, some hexa- and hepta-PCBs, and HCH isomers, with the highest values recorded in winter. The mass concentrations of PAHs, HCH, DDT and its degradation products in the PM10 were significantly higher in winter, while the seasonal minimum and maximum for PCBs differed depending on the chlorination degree of the compound. The diagnostic ratios of PAHs and results of factor analysis, cluster analysis, and principal component analysis indicated the presence of different pollution sources, depending on the location and season (biomass burning, petroleum and fossil fuel combustion, traffic emissions), while PCBs and OCPs were associated with historical or transboundary inputs. The applied statistical tools indicated complex relationships between compounds and differently grouped locations depending on the observed environmental compartment. In addition to local sources, the geographical location of the measurement site also affects the levels of PAHs, PCBs, and OCPs, likely related to different precipitation regimes and airflow patterns. Significant linear correlation between PAHs in TDM and PM10, as well as between PCBs with higher degrees of chlorination in TDM and PM10, suggested that dry deposition likely played a significant role in removing these compounds from the atmosphere. Relationships between individual PAHs, PCBs, and OCPs in soil and TDM indicated the complex circulation mechanisms of these compounds in the environment
The preparation and characterization of ceria amended with copper nanoparticles
No full textCilj ovog rada je pripraviti mezostrukturirani cerijev(IV) oksid (CeO2) te ga oplemeniti nanočesticama bakra (CuNP). Mezostrukturirani cerijev(IV) oksid pripravljen je metodom nanolijevanja u kojoj je silika služila kao mezoporozni predložak. Nanočestice bakra pripremljene su metodom redukcije s NaBH4. Karakterizacija uzoraka provedena je UV-Vis, DLS, XRD, FTIR, SEM/ EDS, UV-Vis DRS te BET analizom. Pripravljeni uzorci sastoje se od finih nepravilnih čestica različitih veličina. Raspodjela cerija, kisika i bakra u uzorcima je homogena, no zapažena je prisutnost zaostalog silicija i natrija. Uzorak dobiven uz više ciklusa uranjanja CeO2 u nanočestice bakra sadrži nešto više bakra. Specifična površina pripravljenih uzoraka CeO2 znatno je manja od SiO2 dok je prosječni promjer pora veći. Uzorci CeO2 bez, i s različitim udjelima bakra ne razlikuju se znatno po specifičnoj površini i promjeru pora. Uzorak CeO2 bez bakra pokazuje bolju katalitičku aktivnost od uzoraka s nanočesticama bakra.The aim of this work is to synthesize mesostructured cerium(IV) oxide (CeO₂) and enhance it with copper nanoparticles (CuNP). The mesostructured cerium(IV) oxide was synthesized using the nanocasting method, where silica was used as a mesoporous template. Copper nanoparticles were prepared by the reduction method using NaBH₄. Sample characterization was carried out using UV-Vis, DLS, XRD, FTIR, SEM/EDS, UV-Vis DRS, and BET analysis. The prepared samples consist of fine irregular particles of varying sizes. The distribution of cerium, oxygen, and copper in the samples is homogeneous, although residual silicon and sodium were observed. The sample obtained after multiple dipping cycles of CeO₂ in the copper nanoparticle solution contains a slightly higher copper content. The specific surface area of the CeO₂ samples is significantly smaller than that of SiO₂, while the average pore diameter is larger. CeO₂ samples with and without different copper contents do not differ significantly in terms of specific surface area and pore diameter. The CeO₂ sample without copper exhibits better catalytic activity compared to the samples with copper nanoparticles
Influence of matrix composition on photolytic and photcatalytic degradation of N-nitrosamines
No full textU procesu dezinfekcije vode mogu nastati dezinfekcijski nusprodukti (DNP) koji su štetni za ljudsko zdravlje. Primjer dezinfekcijskih nusprodukata su nitrozamini koji sadrže dušik te doprinose toksičnosti vode. Zbog toga je neophodno razviti učinkovite metode uklanjanja DNP-a iz vode, kao što su napredni oksidacijski i membranski procesi. U ovom radu istražena je fotolitička i fotokatalitička razgradnja N-nitrozamina korištenjem UV-LED fotoreaktora. Analizirani N-nitrozamini su: N-nitrozo-dimetilamin (NDMA), N-nitrozodietilamin (NDEA),
N-nitrozomorfolin (NMOR) i N-nitrozopiperidin (NPIP). Za izvor zračenja korištene su
UV-A (λ = 365 nm) i UV-C (λ = 272 nm) svjetleće diode. Fotokatalitička razgradnja nitrozamina izvedena je pomoću tankog filma TiO2 te uz pomoć suspenzije TiO2. Fotolitička razgradnja ispitana je u ultračistoj, sintetskoj bazenskoj, morskoj i boćatoj vodi te u retentatu nakon
RO/NF postupka. Istražen je utjecaj valne duljine zračenja, broja LED dioda te sastava matrice na kinetiku razgradnje N-nitrozamina. Rezultati su pokazali da je najučinkovitiji fotoreaktor s najvećim brojem UV-A LED dioda za sve ispitane matrikse tijekom perioda od 60 min.Disinfection by-products (DBP) are harmful to human health and are formed during water disinfection. Examples of disinfection by-products are nitrosamines that contain nitrogen and contribute to the toxicity of drinking water. Therefore, it is necessary to develop effective methods for removing DBPs from water, such as advanced oxidation and membrane processes. In this paper, the photolytic and photocatalytic degradation of N-nitrosamines was investigated using a UV-LED photoreactor. The analyzed N-nitrosamines are:
N-nitroso-dimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosomorpholine (NMOR), and N-nitrosopiperidine (NPIP). UV-A (λ = 365 nm) and UV-C (λ = 272 nm)
light-emitting diodes were used as the radiation source. The photocatalytic degradation of nitrosamines was carried out using a thin film of TiO2 and with the help of a TiO2 suspension. The photolytic degradation was carried out in ultrapure, synthetic pool, sea, and brackish water and in retentate after the RO/NF process. The influence of the radiation wavelength,
the number of LEDs and the type of matrix on the kinetics of N-nitrosamine degradation were investigated. The results showed that the most efficient photoreactor is that with UV-A LED diodes with six columns of UV-LED strips in all tested matrices during a time period of 60 min
Analysis of the effectiveness of the isolated microorganisms in bioremediation of oil and oil products
No full textNafta predstavlja jedan od glavnih energenata današnjice i njena upotreba vrlo je široka. Svakodnevnim korištenjem i eksploatacijom nafte dolazi do neželjenog ispuštanja nafte u okoliš, što predstavlja veliki ekološki problem. Sve se više istražuju nove, „zelene“ tehnologije koje se mogu koristiti za uklanjanje naftnog onečišćenja bez negativnog utjecaja na okoliš. Bioremedijacija može uz prirodne mikroorganizme razgraditi prisutno onečišćenje. Mikroorganizmi proizvode enzime koji razgrađuju naftu i naftne derivate ili koriste naftu kao izvor energije za svoj rast i razmnožavanje. Identifikacija autohtonih mikroorganizama te poznavanje njihovih svojstava od velike je važnosti kako bi se povećala učinkovitost bioremedijacije. U ovom radu provedena je identifikacija i karakterizacija autohtonih mikrobnih kultura iz uzorka tla onečišćenog naftnim derivatima u šaržnim uvjetima i u periodu 28 dana. Dobivene vrijednosti CFU su se kretale u rangu od 6,26 × 10^4 do
7,60 × 10^8 /g tla. Rezultati pokazuju da je aktivnost bakterija i gljiva bila najveća pri pH-vrijednosti 7,8 i 7,0. Na temelju morfologije, biokemijskih testova i MALDI TOF analize identificirane su slijedeće bakterijske vrste: Lysobacter daejeonensis, Cupriavidus necator, Novosphingobium taihuense i Staphylococcus warneri.Oil is one of the most important sources of energy today and its use is widespread. The daily use and exploitation of oil results in the unwanted release of oil into the environment, which is a major environmental problem. New "green" technologies are being explored that can eliminate oil pollution without harming the environment. Bioremediation can break down existing pollution with natural microorganisms. Microorganisms produce enzymes that can break down oil and oil derivatives or use oil as an energy source for their growth and reproduction. Identification of indigenous microorganisms and information about their properties are of great importance to increase the efficiency of bioremediation. In this study, the identification and analysis of the efficiency of microbial cultures from a soil sample contaminated with oil derivatives were carried out under batch conditions over a period of 28 days. The CFU values obtained ranged from 6.26 × 10^4 to 7.60 × 10^8 /g soil. The results show that bacterial and fungal activity was highest at pH 7.8 and 7.0, respectively. Based on morphology, biochemical tests and MALDI TOF analysis, the following bacterial species were identified: Lysobacter daejeonensis, Cupriavidus necator, Novosphingobium taihuense and Staphylococcus warneri
Computational investigation of the interactions of organic pollutants and poly(ethylene terephthalate)
No full textPoli(etilen tereftalat) (PET) je široko korišten polimer, kojeg odlikuju izvrsna mehanička svojstva i kemijska otpornost. Zahvaljujući raširenoj uporabi, često dospijeva u okoliš, gdje se fragmentira na mikro- i nanočestice. U takvom obliku može ostvariti interakcije s raznim organskim onečišćivalima, što ima znatne okolišne implikacije. Ab initio metode pružaju mogućnost detaljnog istraživanja tih interakcija na atomskom nivou, što omogućuje razumijevanje temeljnih sila koje upravljaju vezivanjem organskih molekula na površinu
PET-a. U ovom radu provedeno je istraživanje interakcija između PET-a i dvaju organskih onečišćivala: fenola i anilina, korištenjem DFT metode M06L(GD3)/6-31G(d,p) za geometrijsku optimizaciju modelnih sustava PET-fenol i PET-anilin u softverskom paketu Gaussian. Energija interakcije određena je koristeći osnovni skup 6-31++G(d,p), kako bi se dodatno pokušale bolje opisati disperzijske interakcije. Nadalje, korištena je „counterpoise“ metoda kako bi se korigirala pogreška superpozicije osnovnih skupina. Dobivene energije kompleksacije sustava PET-fenol i PET-anilin su negativne, što ukazuje na stabilnost kompleksa. Međutim, analiza dekompozicije energije otkriva kako sustav PET-anilin ima jače disperzijske interakcije i manju repulziju, što rezultira stabilnijim kompleksom u usporedbi sa sustavom PET-fenol. Elektrostatske interakcije slične su u oba sustava, a parcijalni naboji dobiveni Merz-Kollman analizom ukazuju na jake negativne naboje na kisikovim atomima, što omogućuje stvaranje vodikovih veza. Vizualizacija elektrostatskog potencijala također ide u prilog tomu, pri čemu su kisikovi i dušikovi atomi ključni u stvaranju elektrostatskih interakcija.Poly(ethylene terephthalate) (PET) is a widely used polymer known for its excellent mechanical properties and chemical resistance. Due to its extensive use, it often ends up in the environment, where it fragments into micro- and nanoparticles. In these forms, it can interact with various organic contaminants, leading to significant environmental implications. Ab initio methods provide the opportunity to investigate these interactions in detail at the atomic level, enabling an understanding of the fundamental forces that govern the binding of organic molecules to the surface of PET. In this study, interactions between PET and two organic pollutants, phenol and aniline, were investigated using the DFT method M06L(GD3)/6-31G(d,p) for the geometric optimization of the interacting model systems, i.e., PET-phenol and PET-aniline in the Gaussian software package. The interaction energy was determined using the 6-31++G(d,p) basis set to better account for dispersion interactions. Furthermore, the "counterpoise" method was applied to correct for the basis set superposition error (BSSE). The resulting complexation energies for the PET-phenol and PET-aniline systems were negative, indicating favourable interactions and complex stability. However, the energy decomposition analysis revealed that the PET-aniline system exhibits stronger dispersion interactions and lower repulsion, leading to a more stable complex compared to the PET-phenol system. The electrostatic interactions were similar in both systems, with partial charges obtained from the Merz-Kollman analysis indicating significant negative charges on oxygen atoms, facilitating hydrogen bond formation. The visualization of the electrostatic potential further supported this, showing that oxygen and nitrogen atoms are key contributors to the electrostatic interactions
Removal of xenobiotics by biodegradation using a mixed bacterial culture
No full textNapredak svih ljudskih djelatnosti omogućio je bolju kvalitetu života, ali je i doveo do povećanog ispuštanja ksenobiotika u okoliš koji nepravilnim zbrinjavanjem narušavaju kakvoću okoliša. Sve češći takvi antropogeni spojevi su upravo farmaceutici. Zbog njihove sveprisutnosti u okolišu dolazi do razvijanja otpornosti na antibiotike kod različitih mikrooganizama. Kako bi se riješila problematika ksenobiotika u okolišu, primjenjuje se postupak biorazgradnje. To je ekonomičan i okolišno prihvatljiv postupak koji iskorištava prirodno urođene metaboličke i enzimatske sposobnosti mikroorganizama za razgradnju organskih onečišćujućih tvari. U ovome radu provedeno je istraživanje procesa biorazgradnje β-laktamskog antibiotika amoksicilina pomoću bakterijskih kultura Pseudomonas aeruginosa i Bacillus subtilis. Početne koncentracije amoksicilina izražene preko kemijske potrošnje kisika (KPK) iznosile su 278 mg L^-1 za pokus P1 i 658 mg L^-1 za pokus P2. Za uvid u učinkovitost biorazgradnje provedeni su testovi osjetljivosti i mikroskopska analiza. Učinkovitost procesa biorazgradnje iznosila je za P. aeruginosa 49,6 % i 36,2 % i za B. subtilis 99,7 % i 48,5 % u pokusima P1 i P2.The progress in all human activities has ensured a better quality of life, but it has also led to increased release of xenobiotic compounds into the environment. Due to their improper disposal, they disrupt environmental quality. Such anthropogenic compounds, increasingly present in the environment, are pharmaceuticals. Their ubiquitous presence in the environment contributes to the development of antibiotic resistance in various microorganisms. To solve the problem of xenobiotics in the environment, the biodegradation process is used. This is an economical and environmentally friendly process that utilizes the natural metabolic and enzymatic abilities of microorganisms to degrade organic pollutants. In this study, research was conducted on the biodegradation process of the β-lactam antibiotic amoxicillin using bacterial cultures of Pseudomonas aeruginosa and Bacillus subtilis. Initial concentrations of amoxicillin, expressed in terms of chemical oxygen demand (COD) values, were 278 mg L^-1 and 658 mg L^-1 for experiments P1 and P2. To gain insight into the efficiency of biodegradation, sensitivity tests and microscopic analyses were performed.
The biodegradability was 49.6 % and 36.2 % for P. aeruginosa and 99.7 % and 48.5 % for
B. subtilis in trials P1 and P2, respectively
Modification of poly(3,4-ethylenedioxythiophene) to produce a conductive polymer for flexible electronics
No full textFleksibilna elektronika postala je održiva alternativa tradicionalnoj čvrstoj elektronici, s naglaskom na razvoj nosivih i prilagodljivih elektroničkih uređaja. Međutim, njezin napredak ograničen je nedostatkom materijala koji istovremeno posjeduju visoku električnu vodljivost, mehaničku fleksibilnost i dugotrajnu stabilnost. Ovaj rad usmjeren je na razvoj novih istezljivih i vodljivih polimernih materijala temeljenih na modificiranom poli(3,4-etilendioksitiofenu) (PEDOT) kako bi se poboljšala njihova mehanička svojstva, fleksibilnost i mogućnost samozacjeljivanja. Primijenjena su dva pristupa: modifikacija PEDOT-a bočnim poli(akril-uretan) (PAU) lancima te izrada kompozita PEDOT-a s termoplastičnim elastomerom stiren/etilen-ran-butilen/stiren(SEBS). Prvi pristup uključivao je sintezu graft kopolimera PEDOT-g-PAU metodom radikalske polimerizacije uz prijenos atoma (engl. atom transfer radical polymerization, ATRP). Cilj ove modifikacije bio je poboljšanje mehaničkih svojstava PEDOT-a putem ugradnje molekulskih vrsta koje međusobno ostvaruju vodikove veze. Takav pristup omogućuje nekovalentno umrežavanje putem vodikovih veza bočnih lanaca PAU, što povećava istezljivost i fleksibilnost materijala, dok istovremeno glavni lanac PEDOT-a zadržava konjugaciju i vodljivost. Uspješna sinteza graft kopolimera potvrđena je infracrvenom spektroskopijom s Fourierovom transformacijom (engl. Fourier-transform infrared spectroscopy, FTIR) i nuklearnom magnetskom rezonancijom (engl. nuclear magnetic resonance, NMR), dok je diferencijalnom pretražnom kalorimetrijom (engl. differential scanning calorimetry, DSC) uočeno značajno sniženje temperature staklastog prijelaza, čime je dokazana poboljšana fleksibilnost materijala. Kako je jedna od tehnologija izrade fleksibilne elektronike inkjet ispis i priprema funkcionalnih slojeva na fleksibilnim podlogama, sintetizirani kopolimeri dalje su pripremljeni u obliku vodljive tinte te su inkjet tehnikom ispisani u tri i pet slojeva na poliuretansku (PU) podlogu. Električna provodnost vodljivog sloja bila je između
1,0 S m^-1 i 2,9 S m^-1 u neistegnutom stanju te između 1,6 S m^-1 i 4,1 S m^-1 pri istezanju. Porast vodljivosti kod istegnutih uzoraka može se pripisati boljem poravnanju lanaca i lakšem protoku elektrona tijekom istezanja. Kako bi se simulirala realna primjena u nosivoj elektronici i dodir s kožom, ispitana je adhezija i stabilnosti ispisanog sloja u modelnoj otopini ljudskog znoja. Svi sintetizirani uzorci pokazali su visoku stabilnost i dobru adheziju ispisanog sloja s podlogom, bez znakova delaminacije. Svi uzorci također su pokazali visoku fleksibilnost, jer ih je bilo moguće savijati i istezati iznad 300 % bez pucanja. Uspješna primjena inkjet tehnike potvrđuje mogućnost obrade ovih materijala u obliku funkcionalnih slojeva na fleksibilnim podlogama, što ih čini pogodnima za primjenu u fleksibilnoj elektronici. Drugi pristup obuhvaćao je sintezu kompozita modificiranog PEDOT-a s termoplastičnim elastomerom SEBS i izradu tankih filmova izlijevanjem na staklu. Uspješno graftiranje PAU bočnih lanaca na PEDOT strukturu u otopljenom sulfoniranom SEBS-u (S-SEBS) potvrđeno je FTIR analizom, dinamičkim raspršenjem svjetlosti (engl. dinamic light scattering, DLS) i mjerenjem kontaktnog kuta. Ovi kompoziti pokazali su poboljšana mehanička svojstva, povećanu fleksibilnost i sposobnost samozacjeljivanja što je potvrđeno snimanjem spojeva pretražnom elektronskom mikroskopijom (engl. scanning electron microscopy, SEM). Prekidno istezanje povećano je s 204 % na 346 %, dok je prekidna čvrstoća porasla sa 7,0 MPa na 11,9 MPa. Ispitivanjem električne vodljivosti utvrđeno je da PAU-modifikacija smanjuje vodljivost s
310 S m^-1 na 93 S m^-1, no nakon dopiranja vodljivost je porasla na 288 S m^-1. Iako dolazi do pada vodljivost nakon graftiranja PAU, dobivene vrijednosti vodljivosti su dva do tri reda veličine veće u odnosu na filmove pripremljene inkjet ispisom. Materijal je također pokazao stabilnost u simuliranim uvjetima primjene, dok je zacijeljeni spoj pokazao postojanu strukturu i integritet pod naprezanjem. Primjena razvijenog materijala testirana je na izradi jednostavnog elektromiografskog (engl. electromyography, EMG) senzora za praćenje električne aktivnosti mišića. Graftirani uzorci pokazali su višu amplitudu, bolju definiciju vrhova, veću stabilnost signala tijekom vremena te konzistentniji frekvencijski odziv u usporedbi s nemodificiranim PEDOT-om. Ovi rezultati ukazuju na to da bi PEDOT-g-PAU:S-SEBS materijali mogli imati značajan doprinos u razvoju fleksibilnih senzora i bioelektroničkih sustava. Zaključno, rezultati istraživanja potvrđuju da materijali na osnovi PEDOT-a modificiranog ugradnjom dinamičkih nekovalentnih vodikovih veza predstavljaju značajan iskorak u razvoju fleksibilnih elektroničkih materijala. Integracija PAU lanaca poboljšala je mehanička svojstva i samozacjeljivanje uz zadržavanje dovoljne električne vodljivosti za praktične primjene. Postignuta kombinacija istezljivosti, vodljivosti i mogućnosti obrade inkjet ispisom otvara potencijal za primjenu u fleksibilnoj elektronici, nosivim uređajima i mekoj robotici. Ovi materijali nude novu perspektivu za daljnja istraživanja i razvoj u području funkcionalnih polimera za napredne elektroničke primjene.Flexible electronics has become a sustainable alternative to traditional rigid electronics, focusing on the development of portable and adaptable electronic devices. However, their progress is limited by the lack of materials that simultaneously exhibit high electrical conductivity, mechanical flexibility and long-term stability. This study focuses on the development of novel stretchable and conductive polymer materials based on modified poly(3,4-ethylenedioxythiophene) (PEDOT) to improve their mechanical properties, flexibility and self-healing ability. Two approaches were used: the modification of PEDOT with poly(acryl-urethane) side chains (PAU) and the fabrication of PEDOT composites with the thermoplastic elastomer styrene/ethylene-ran-butylene/styrene (SEBS). The first approach involved the synthesis of PEDOT-g-PAU graft copolymers using atom transfer radical polymerization (ATRP). The aim of this modification was to improve the mechanical properties of PEDOT by incorporating molecular species capable of forming hydrogen bonds. This strategy enables non-covalent crosslinking via hydrogen bonds between the PAU side chains, increasing the stretchability and flexibility of the material while maintaining the conjugation and conductivity of the PEDOT backbone. The successful synthesis of the graft copolymers was confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR), while differential scanning calorimetry (DSC) revealed a significant decrease in the glass transition temperature, indicating improved flexibility of the material. As one of the key technologies in flexible electronics is inkjet printing for the deposition of functional layers on flexible substrates, the synthesized copolymers were further processed into conductive inks and printed in three and five layers on a polyurethane (PU) substrate using inkjet techniques. The electrical conductivity of the conductive layer was between 1.0 S m^-1 and 2.9 S m^-1 in the unstretched state and between 1.6 S m^-1 and 4.1 S m^-1 in the stretched state. The increase in conductivity during stretching can be attributed to better chain alignment and easier electron transport during deformation. To simulate real applications in wearable electronics and skin contact, the adhesion and stability of the printed layer were tested in a model solution of human sweat. All synthesized samples showed high stability and strong adhesion to the substrate with no signs of delamination. In addition, all samples showed excellent flexibility, allowing bending and stretching by more than 300% without cracking. The successful application of inkjet printing confirms the feasibility of processing these materials into functional layers on flexible substrates, making them suitable for use in flexible electronics. The second approach involved the synthesis of composites based on modified PEDOT with SEBS and the fabrication of thin films by solution casting on glass. The successful grafting of PAU side chains onto the PEDOT structure dissolved in sulphonated SEBS (S-SEBS) was confirmed by FTIR analysis, dynamic light scattering (DLS) and contact angle measurements. These composites exhibited improved mechanical properties, increased flexibility and selfhealing ability, as confirmed by scanning electron microscopy (SEM) of the healed interfaces. Elongation at break increased from 204% to 346%, while tensile strength improved from 7.0 MPa to 11.9 MPa. Measurements of electrical conductivity showed that the PAU modification reduced conductivity from 310 S m^-1 to 93 S m^-1, while doping increased it to 288 S m^-1. Despite the decrease in conductivity after PAU grafting, the conductivity values achieved were two to three orders of magnitude higher than inkjet-printed films. The material also proved to be stable under simulated application conditions and the healed interfaces maintained their structural integrity under stress. The developed material was tested in the fabrication of a simple electromyography (EMG) sensor for monitoring electrical muscle activity. The grafted samples showed higher amplitude, better peak definition, greater signal stability over time and a more consistent frequency response compared to unmodified PEDOT. These results suggest that PEDOT-g-PAU:S-SEBS materials could make a significant contribution to the development of flexible sensors and bioelectronic systems. In summary, the research results confirm that PEDOT-based materials modified by incorporating dynamic non-covalent hydrogen bonding represent a significant advance in the development of flexible electronic materials. The integration of PAU chains improved the mechanical properties and self-healing capabilities while maintaining sufficient electrical conductivity for practical applications. The achieved combination of stretchability, conductivity and inkjet printability opens up new possibilities for applications in flexible electronics, wearable devices and soft robotics. These materials offer a new perspective for further research and development in the field of functional polymers for advanced electronic applications