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Enzymatic synthesis and membrane purification of fructo‐oligosaccharides
No full textU okviru ove doktorske disertacije razvijeni su postupci sinteze frukto-oligosaharida (FOS)
primenom slobodne i imobilisane fruktoziltransferaze (FT) iz industrijskog preparata
Pectinex® Ultra SP-L. Primenom slobodne FT i izborom optimalnih uslova dobijena je smeša
koja sadrži 60,2 % FOS i sporedne proizvode poput saharoze i monosaharida. Radi razvijanja
efikasnijih postupaka proizvodnje FOS koji podrazumevaju primenu imobilisanih preparata, FT
je imobilisana na nosače različitih funkcionalnih karakteristika putem adsorpcije ili
kovalentnog vezivanja. Posebno pogodnim pokazali su se nemodifikovani i epoksi
modifikovani Purolite® A109 nosač čijom je primenom omogućena selektivna imobilizacija FT,
a time i delimično prečišćavanje preparata od drugih enzima. Imobilisani preparati su
upotrebljeni za proizvodnju FOS u šaržnom i pneumatskom reaktorskom sistemu. S obzirom
na njihovu izuzetnu operativnu stabilnost, razvijeni su i kontinualni procesi proizvodnje FOS.
Dobijena smeša FOS podvrgnuta je i prečišćavanju primenom nanofiltracije sa dijafiltracijom.
Izvođenjem ovog procesa pri izabranim optimalnim uslovima, dobijena je smeša čistoće 87,2 %
FOS. Radi dodatnog unapređenja procesa prečišćavanja, primenjen je i membranski reaktor gde
je simultanim izvođenjem sinteze FOS i prečišćavanja, nakon 9 h dobijena smeša sa 91,8 % FOS.
Visokoprečišćena smeša FOS testirana je u in vitro TIM-2 sistemu koji uključuje primenu ljudske
crevne mikrobiote i simulira procese varenja u debelom crevu, gde rezultati potvrđuju
postojanje prebiotskog potencijala. Primenom stečenih znanja, razvijen je i funkcionalni
proizvod izvođenjem in situ biokonverzije saharoze u FOS primenom FT i komercijalnog
javorovog sirupa. Ovim pristupom dobijen je javorov sirup sa dodatom vrednošću, smanjenog
kalorijskog sadržaja i poboljšanih funkcionalnih karakteristika uz zadržavanje standardnih
parametara kvaliteta.As part of this doctoral dissertation, procedures for the synthesis of fructo-oligosaccharides
(FOS) were developed using free and immobilized fructosyltransferase (FT) from the industrial
preparation Pectinex® Ultra SP-L. By applying free FT under selected optimal conditions, a
mixture containing 60.2 % FOS and by-products such as sucrose and monosaccharides. To
develop a more efficient FOS production process that involves immobilized preparations, FT is
immobilized on supports with different functional characteristics via adsorption or covalent
binding. The unmodified and epoxy-modified Purolite® A109 support are considered
particularly suitable supports, which enabled selective immobilization of FT, and thus partial
purification of the preparation from other enzymes. The immobilized preparations were used
for the FOS production in batch and air-lift reactor system. Considering their exceptional
operational stability, continuous FOS production processes have been developed. The
synthesized FOS mixture was subjected to purification using nanofiltration with diafiltration.
By performing this process under the selected optimal conditions, a mixture with a purity of
87.2 % FOS was obtained. To improve the purification process, a membrane reactor was used,
where the simultaneous execution of the FOS synthesis and purification resulted in a mixture
with 91.8 % FOS after 9 h. The highly purified FOS mixture was tested in the in vitro TIM-2
system, which includes the application of human gut microbiota and simulates digestion
processes in the large intestine, where the results confirm the existence of prebiotic potential.
By applying the acquired knowledge, a functional product was developed by performing in situ
bioconversion of sucrose into FOS using FT and commercial maple syrup. This approach
resulted in a value-added maple syrup with reduced caloric content and improved functional
characteristics while maintaining standard quality parameters
Adsorption of cadmium and zinc ions onto fly ash-based geopolymer
No full textObjective
Fly ash, a combustion byproduct generated in coal-fired thermal power plants, is predominantly
disposed of in landfills, leading to significant environmental risk. This research focuses on
valorizing fly ash as a precursor material for the synthesis of geopolymers with enhanced
adsorption capacities. The conversion of fly ash into geopolymer adsorbents not only reduces the
volume of hazardous waste deposited in landfills but also enables efficient remediation of heavy
metal-contaminated water. This approach integrates waste management with environmental
purification by exploiting the physicochemical properties of geopolymer materials derived from
industrial waste
Chitosan–Hydrazone-Modified Calcium Phosphate Scaffolds: Fabrication, Characterization, and Drug Delivery Potential
No full textBackground/Objectives: Recent advancements in biomaterials aimed at closely mimicking natural biological tissues hold great promise for hard tissue regeneration and controlled drug release due to their superior physical, chemical, and biological properties. This study aimed to develop multi-ion doped calcium hydroxyapatite (HAp) scaffolds with chitosan-based coatings for localized drug delivery, incorporating a novel hydrazone compound with potential anticancer activity. Methods: HAp powders doped with magnesium (Mg2+), strontium (Sr2+), and varying fluoride (F−) contents (0–2 mol.%) were synthesized via a hydrothermal method. Scaffolds were fabricated using the sponge replica technique and subsequently coated with chitosan or a chitosan–hydrazone blend. Dopant incorporation was confirmed by electron dispersive X-ray spectroscopy (EDS). Phase composition and morphology were analyzed via X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties, bioactivity, cytotoxicity, and hydrazone release profiles were systematically evaluated. Results: EDS confirmed successful incorporation of Mg2+ and Sr2+ in all powders, while F− was detected only in powders with 1 and 2 mol.% fluoride. XRD and SEM revealed the phase composition and scaffold microstructure. Chitosan coatings significantly improved scaffold compressive strength and reduced degradation rate, indicating enhanced stability in biological environments. The coated scaffolds supported MRC-5 fibroblast viability. The hydrazone compound exhibited dose-dependent antitumor cytotoxicity comparable to cisplatin and showed sustained release from scaffolds for up to 15 days. Conclusions: The combination of multi-ion doped HAp scaffolds and chitosan–hydrazone coatings provides a promising platform for bone tissue engineering and localized cancer therapy, demonstrating both mechanical stability and controlled, sustained drug release
The Impact of Various Temperatures on Polyphenol and Flavonoid Extraction from Fumaria officinalis Herba
No full textThe objective of the present study was to investigate the influence of high temperature on the extraction of polyphenols and flavonoids from Fumaria officinalis. The polyphenol yield varied from 16.56 to 18.33 mg gallic acid equivalent/g of dried plant material, achieving the highest value in the extract prepared using heat-assisted extraction (HAE) for 30 min. The same trend was noticed for the flavonoid concentration in the extracts (7.14–8.48 mg catechin equivalent/g of dried plant material): macerate after 60 min ≤ macerate after 90 min ≤ HAE extract after 15 min ≤ HAE extract after 30 min. Compared to maceration and taking into consideration the industrial requirements such as high extraction yield for a shorter time, HAE could be recommended as a convenient technique for polyphenol and flavonoid extraction from fumitory.The IX International Congress “Engineering, Environment and Materials in Process Industry”—EEM2025, 2-4 April 2025, Bijeljina, Bosnia and Herzegovin
Mathematical Modeling of the Electrostatic Extrusion Process
No full textПредмет овог рада је постављање математичког модела процеса електростатичке екструзије. Овај процес подразумева примену електричног поља на течност која истиче из капиларне цеви при чему долази до формирања танког млаза течности и атомизације у капи микронских величина. Примењују се у биотехнологији за добијање инкапсулата и имобилисаних биокатализатора у виду микрочестица.
На основу лабораторијских експерименталних података из литературе постављена је полуемпиријска корелација величине честица са релевантним параметрима у процесу електростатичке екструзије. Затим је проширен софтвер за рачунарску динамику флуида OpenFOAM® електрохидродинамичким (ЕХД) моделом савршеног диелектрика и изведен је потпуно нови електромагнетофлуидодинамички (ЕМФД) модел. По први пут је ЕМФД модел укључен у софтвер за рачунарску динамику флуида. Оба модела се могу применити на двофазне системе. Модели су изведени полазећи од Навије-Стоксове једначине увођењем одговарајућих израза који описују дејство електричног или електромагнетног поља. Нови ЕМФД модел је генерално применљив на протицање при утицају електричног или магнетног поља. Може се користити и за високо-проводљиве флуиде. Употребом ЕХД и ЕМФД модела израчунате су деформације капи. Први пут је симулирано електропредење употребом Навије-Стоксове једначине и добијени су пречници млаза. Симулиран је електроспреј процес и предвиђене величине честица добијене електростатичком екструзијом. Провера модела је показала добро слагање нумерички добијених вредности ових величина са вредностима литературних експерименталних резултата и теоријски изведених једначина. Ова докторска теза даје научни допринос развоју електромагнетофлуидодинамике.The subject of this work is the establishment of a mathematical model of the electrostatic extrusion process. In this process an electric field influences a liquid exiting a capillary tube while a thin liquid jet is formed and atomization of microdrops occurs. This process is used for obtaining encapsulates and immobilized biocatalysts in the form of microparticles in biotechnology.
A semi-empirical correlation of particle size with relevant process parameters for the electrostatic extrusion process is established based on laboratory experimental data from literature. Afterwards, the computational fluid dynamics (CFD) software OpenFOAM® is expanded with a perfect dielectric model from electrohydrodynamics (EHD) and a totally new electro-magneto-fluid dynamics (EMFD) model is derived. An EMFD model is implemented into CFD software for the first time. Both models can be applied to two-phase systems. The models were derived starting from the Navier-Stokes equation by including appropriate expressions that describe the electric or electromagnetic field. The new EMFD model is generally applicable to flow influenced by an electric or magnetic field. It can be used for high conductivity fluids. Drop deformations were calculated by using the EHD and EMFD model. The electrospinning was simulated by using the Navier-Stokes equation for the first time and the jet diameters were obtained. The electrospraying process was simulated and the size of particles obtained in the electrostatic extrusion process is predicted. Numerically obtained values were in good agreement with experimental results from literature and theoretically derived equations during the model testing. This doctoral dissertation scientifically contributes to the development of the electro-magneto-fluid dynamics
Polyaniline/TiO2 heterostructure: the efficient photocatalyst for diazepam degradation under simulated solar light
No full textAs pharmaceuticals have become significant wastewater pollutants [1], the objective ofthis work was to design efficient PANI/TiO2 photocatalysts for degradation of psychiatricdrug diazepam since both, titanium dioxide (TiO2) and polyaniline (PANI) are highlyappropriate for photocatalytic application. Hence, PANI/TiO2 heterostructures withdifferent amounts of PANI (0, 1, 3, 5 wt.%) were obtained by mixing TiO2 synthesizedby using hydrothermal method and PANI prepared via chemical oxidativepolymerization. The obtained samples were characterized by XRD, FT-IR, FESEM,EDS, DLS, and UV/Vis methods, while their photocatalytic efficiency was examined byUV/Vis and TOC methods. The tetragonal anatase with preserved structure was obtainedin all the samples, with crystallites sized of about 25 nm. EDS analysis revealed that thePANI/TiO2 heterostructures were successfully formed. According to FESEM, TiO2created spherical particles with an average size of 23 nm, while PANI consisted of fiberswith an average length of 300 nm. Interestingly, with an increase in PANI content,particle size distribution was wider. According to the absorption spectra, the absorptionedge of PANI/TiO2 was shifted to the visible light region compared to pristine TiO2. Allthe samples showed photocatalytic activity towards diazepam, while 1%PANI/TiO2 wasthe most efficient by degrading 95.9% of this drug after 210 min under simulated solarlight. Moreover, this heterostructure showed high mineralization efficiency as well,which was confirmed by TOC measurements. The performed kinetic analysis revealedthat the photocatalytic degradation of diazepam in this work can be well described bypseudo-first kinetic order. The highest value of reaction rate constant (0.017(1) min−1)was obtained for the 1%PANI/TiO2. Finally, based on scavenger tests andelectrochemical calculations, the diazepam photocatalytic degradation in the presence of1%PANI/TiO2 heterostructure under simulated solar light follow direct Z-scheme typeof mechanism
Green Methodology for Producing Bioactive Nanocomposites of Mesoporous Silica Support for Silver and Gold Nanoparticles Against E. coli and S. aureus
No full textThis study considered and compared silver, gold, and their combination of nanoparticles (AgNPs, AuNPs, and Au-AgNPs) with biocompatible material mesoporous silica SBA-15 as potential antibacterial agents. A facile, one-pot “green” methodology, utilizing L-histidine as a reducing agent and bridge between components, was employed to obtain Ag@SBA-15, Au@SBA-15, and Au-Ag@SBA-15 nanocomposites without the use of external additives. Various physicochemical tools (UV-Vis, TEM, SAED, FESEM, XPS, BET, XRD, and FTIR) presented SBA-15 as a good carrier for spherical AgNPs, AuNPs, and Au-AgNPs with average diameters of 8.5, 16, and 9 nm, respectively. Antibacterial evaluations of Escherichia coli and Staphylococcus aureus showed that only Ag@SBA-15, at a very low Ag concentration (1 ppm) during 2 h of contact, completely reduced the growth (99.99%) of both strains, while the Au@SBA-15 nanocomposite required higher concentrations (5 ppm) and time (4 h) to reduce 99.98% E. coli and 94.54% S. aureus. However, Au introduction in Ag@SBA-15 to form Au-Ag@SBA-15 negatively affected its antibacterial potential, lowering it due to the galvanic replacement reaction. Nevertheless, the rapid and effective combating of two bacteria at low NPs concentrations, through the synergistic effects of mesoporous silica and AgNPs or AuNPs, in Ag@SBA-15 and Au@SBA-15 nanocomposites, provides a potential substitute for existing bacterial disinfectants
Influence of Iron on the Mullite Formation
No full textInfluence of iron on the crystallization mechanism of mullite obtained from the hybrid
gels and doped with different concentrations of iron was examined. DTA analysis showed that
iron addition had a beneficial effect on the mullite formation leading to the temperature
decreasing as the amount of iron increased. X-ray diffraction and Mössbauer spectroscopy
confirmed the increased iron content in the mullite lattice, which led to an increase in the unit
parameter and was related to the higher iron content in regular octahedra, disordered
octahedra, and tetrahedra with oxygen vacancies. Plate-like morphology observed by SEM
suggests the two-dimensional crystal growth (n = 2). The most prominent kinetic models were
used to estimate n and Ea from the DTA curves. Ea values increases as iron content increase,
indicating that mullitization slows down due to iron incorporation. The Ea values for the
undoped mullite sample ranged from 820 to 860 kJ/mol, from 820 to 890 kJ/mol for the irondoped mullite sample containing 6.0 wt% of Fe2O3, and from 960 to 1060 kJ/mol for the irondoped mullite sample containing 12 wt% of Fe2O3.Утицај гвожђа на механизам кристализације мулита додијеног из
хибридних гелова допираних различитим концентрацијама гвожђа испитивани су
методом диференцијалне термијсе анализе (ДТА). ДТА метода је показала да додатак
гвожђа има позитиван утицај на формирање мулита што се потврђује смањењем
температуре формирања са повећањем концентрације гвожђа. Рендгенском
дифракцијом и Мезбауеровом (Mössbauer) спектроскопијом потврђено је повећање
садржаја гвожђа у кристалној решетки мулита, што доводи до повећања
параметара решетке, а у вези је са већим сарджајем гвожђа у регуларним
октаедрима, октаедрима нарушене структуре и тетраедрима са кисеоничним
вакансијама. Морфологија плочастих честица, која је потврђена скенирајућом
електронском микроскопијом, указује на дводимензионални раст (n = 2). За
одређивање Аврамијевохг коефицијента (n) и енергије активације (Eа) из резултата
ДТА коришћене су најпознатији кинетички модели. Вредности енергије активације
процеса формирања мулита расте са повећањем сарджаја гвожђа, што указује да се
процес мулитизације успорава због уградње гвожђа у кристалну решетку мулита.
Енергије активације за узорка недопираног мулита варирају у опсегу 820 до 860 kJ/mol,
за узорак са 6.0 mas % Fe2O3 820 до 890 kJ/mol, док су за узорак са 12 mas % of Fe2O3 у
опсегу 960 – 1060 kJ/mol
Causes of Occurrence and Methods of Prevention of Corrosion of Cans for Food Products
No full textThe corrosion resistance and material properties of tinplate cans used in a food production facility in Serbia were analyzed to identify the causes of corrosion occurring at the junction between the lid and the can body. The composition of the steel sheet, the tin coating, the type of passive layer, and the organic coating were determined using different analytical methods (XRF, SEM/EDS, and FTIR). Corrosion resistance was determined using the EIS method and by directly immersing the samples with an artificial defect in a diluted NaCl solution. The tin coating was passivated with titanium oxide, to which an organic coating was applied. When filled cans are laced, at the joint between the lid and the can body, the organic coating is locally damaged, and subsequently, steel corrosion occurs. The insufficient thickness of the tin coating (~0.1 µm), and pour wet adhesion of the organic coating are the main causes of steel corrosion in the gap between the lid and the can body. The application of the passive layers that ensure good adhesion of the covering organic coating and application an organic coatings of the new generation that have property of self-healing is probably the promising solution for this problem
One-pot synthesis of lemon peel/zero-valent iron catalyst for Fenton degradation of 2-chlorophenol in aqueous solutions
No full textThe present study investigates the utilization of lemon peel, an agricultural byproduct, and iron oxide, for the synthesis of an efficient catalyst designed to degrade 2-chlorophenol via the Fenton reaction. The catalysts were obtained through a single-step carbothermal reduction process conducted at 800 °C. The study systematically evaluated the effects of the biomass/iron oxide ratio, initial pH, hydrogen peroxide concentration, catalyst dosage, and the presence of various salts and natural organic matter on the overall degradation efficiency. The results demonstrated the efficacy of lemon peel as a carbonaceous precursor essential for the in-situ reduction of Fe2O3 to zero-valent iron decorated with Fe3O4 particles. An optimal mass ratio of lemon peel to iron oxide of 4:1 was identified. Under optimized conditions (pH 2, 45 min), the prepared catalyst achieved substantial 2-chlorophenol degradation rates of 94 % in aqueous solution, with above 85 % TOC reduction, and a leached iron content of 5.2 %. Notably, this degradation rate was achieved within a significantly shorter timeframe than previously reported systems. Furthermore, the presence of chloride ions reduced the degradation efficiency to 84 %, while the presence of nitrate ions and humic acid did not have a significant influence, suggesting that the investigated catalyst could also be efficient in removing 2-chlorophenol from groundwater. Hence, the findings of this research confirm that the valorisation of waste streams through pyrolytic conversion represents an efficient, sustainable, and cost-effective methodology for producing high-performance catalysts applicable to the remediation of water resources contaminated with 2-chlorophenol