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Physico-chemical, technological and radiological characteristics of kaolinized granite from Northwestern Serbia
No full textIn the ceramic industry, the quality of the final ceramic tile as well as the possibility of its use depends on the quality and characteristics of the starting raw materials. One of the potential raw materials that can be used in the production of ceramic tiles is kaolinized granite, and it is necessary to examine its characteristics. In this research, the kaolinized granite of the Jadar block, northwestern Serbia, from the Beli Majdan surface mine, Jadranska Lešnica, was examined. Chemical analysis, X-ray diffraction analysis (XRD), and differential thermal analysis (DTA) were carried out. Ignition tests of the prepared composites were also conducted at three selected temperatures (1000, 1100, and 1250°C), where total linear shrinkage and water absorption were determined. The activity concentrations of natural radionuclides and the artificial radionuclide 137Cs were determined using the gamma spectrometry method, and then the radiation risk for the external exposure of workers when working with this raw material was assessed. For the samples with the highest content of 226Ra, radon exhalation measurements were performed with the RAD7 device, and the values of the radon emanation coefficient were determined, as well as the values of alpha dose equivalents, which quantified the potential internal exposure of workers. The results of the chemical analysis showed that the content of Al2O3 in the examined composites ranged from 19.11-21.00%, and the content of Fe2O3 from 1.53-1.72%. Additionally, the K2O content in the tested composites ranges from 4.01-5.46%, which indicates the presence of K-feldspar and muscovite, and the Na2O content from 1.82-2.61%. Based on XRD analysis, it was established that the mineral composition of kaolinized granite includes quartz, feldspar, mica, calcite/dolomite, and kaolinite minerals. DTA analysis indicates the occurrence of minor endothermic processes at 488.05°C and 558.12°C, as well as an exothermic process at 980.8°C. The color of the ignition is brick red to dark brown red. A trend of increasing linear shrinkage and decreasing water absorption with increasing ignition temperature was observed with the normal appearance of the samples. The average activity concentration of natural radionuclides are around and below the average values for building materials, expect for 40K. The values for 137Cs are below the values measured in soil. Annual effective doses estimated for external exposure are below 1 mSv y-1, which indicates that there is no increased radiation risk when working with this raw material. The values of the radon mass exhalation rate are in the range of 61-113 mBq kg-1 h-1, and the values of the radon emanation coefficient are 6.3-8.4%. The average value of the alpha dose equivalent is 1mSvy-1, which indicates a potential exposure to radon below 100 Bq m-3. Based on the obtained results, it can be concluded that kaolinized granite is a high-quality and radiologically safe raw material for making ceramic composites in the production of ceramic tiles. It has all the necessary characteristics to partially or completely replace feldspar in ceramic composites
Razvoj i primena metode XRF unapređena sa tehnikama mašinskog učenja za određivanje sastava troske u industriji čelika
No full textU industriji čelika, poznavanje sastava troske ključno je za optimizaciju procesa topljenja, smanjenje utroška energije, materijala i negativnog uticaja na životnu sredinu. Konvencionalne metode analize suočavaju se problemima poput dugotrajne pripreme uzorka i relativno velikih troškova, zbog čega se u praksi izbegava redovna analiza sastava troske. Osim toga razvijene su i brze metode zasnovane na XRF spektrometriji, kojima se obezbeđuje brza istovremena analiza više uzoraka kako bi se zadovoljili zahtevi za visokom preciznošću u raznim industrijama poput čelika, bakra, aluminijuma, cementa i u sferi rudarstva. Ovo tehničko rešenje predstavlja razvoj procedure za XRF analize koja je unapređena tehnikama mašinskog učenja za efikasnu analizu sastava troske. Ovo rešenje omogućava brzu, preciznu i pouzdanu analizu hemijskog sastava troske. Pored toga, integracijom sa istorijskim podacima procesa topljenja, razvijena je i metodologija koja omogućava predviđanje sastava troske, što dodatno doprinosi obuhvatnijem materijalnom i energetskom bilansu. Primena ovog rešenja u praksi prikazana je na primeru elektrolučne peći kapaciteta 60 tona, gde su optimizacija procesnih parametara i strategije upravljanja otpadom pokazale značajna poboljšanja u efikasnosti i održivosti proizvodnje čelika
Organobentonites as perspective adsorbents for nonsteroidal anti-inflammatory drug - diclofenac sodium
No full textVarious chemical substances found in natural water sources and wastewater are considered as emerging
contaminants since they exhibit resistance to traditional water treatment methods and persist in treated effluents.
Of particular concern are pharmaceuticals, given to their widespread use and potential adverse effects on
human health, especially when they contaminate drinking water (Rivera-Utrilla et al., 2013). Nonsteroidal antiinflammatory
drugs (NSAIDs), such as diclofenac, ibuprofen, and naproxen, commonly used in both human and
veterinary medicine for pain relief, are frequently detected in various water bodies, raising concerns about their
environmental impact. Diclofenac has attracted global attention as an emerging contaminant, especially after its
veterinary use was linked to the decline of scavenger bird populations. Additionally, studies have emphasized
the adverse effects of diclofenac on aquatic organisms, further highlighting its environmental significance
(Lonappan et al., 2016). Different methods have been explored for removal of emerging contaminants from
water sources, including advanced oxidation processes, activated sludge, adsorption, membrane filtration, and
others (Rivera-Utrilla et al., 2013). Among the techniques for effective removal of NSAIDs from polluted
water, adsorption onto different materials such as activated carbons, clays, and zeolites is a promising approach
(Smiljanić et al., 2020; Obradović et al., 2022).
This research aims to investigate the potential of modified bentonite in the removal of diclofenac from water
solution. The natural bentonite from the Šipovo deposit in Bosnia and Herzegovina underwent modification
using dodecylamine - an aliphatic primary amine, and di(hydrogenated tallow)dimethylammonium chloride - a
quaternary ammonium salt known under a tradename Arquad®2HT-75. Both surfactants were used in quantities
equivalent to 50% and 100% of the bentonite’s cationic exchange capacity. Analysis of the prepared samples
via Fourier-transform infrared spectroscopy and simultaneous thermal analysis confirmed the presence of the
surfactant in the modified bentonites. Adsorption isotherms demonstrated that the adsorption of diclofenac
increased with the increase of surfactant amount, as well as with the increase of the initial pharmaceutical
concentrations. The highest adsorption of the drug occurred with bentonite containing the highest surfactant
concentration, with slightly higher adsorption reported for composites with Arquad®2HT-75. Considering that
natural bentonite exhibits minimal affinity for diclofenac removal, these findings indicate that organobentonites
have significant potential as effective adsorbents for eliminating diclofenac from contaminated water sources
Coal to Clean: Comparing Advanced Electrodes for Desulfurization and Copper Recovery
No full textThis study explores the electrochemical desulfurization of coal and the recovery of copper
(Cu) using dimensionally stable anode (DSA) electrodes. Background: The research addresses
the need for effective sulfur removal from coal to reduce emissions. Methods: Electrochemical
desulfurization was conducted using DSA and graphite electrodes, evaluating parameters like
activation energy, desulfurization rate, and energy consumption. Cyclic voltammetry and linear
sweep voltammetry were used to study the electrochemical properties. Results: The DSA electrode
demonstrated superior performance with higher desulfurization rates, lower activation energy, and
better response to temperature increases compared to the graphite electrode. Optimal desulfurization
was achieved at 50 ◦C with the DSA electrode, balancing efficiency and energy consumption. Copper
recovery from the solution post-desulfurization was effective, with an 86.34% recovery rate at −0.15 V
vs. (Ag|AgCl). The energy consumption for the Cu recovery was calculated to be 10.56 J, and the
total cost for recovering 1 ton of Cu was approximately 781.20 €. Conclusions: The study highlights
the advantages of DSA electrodes for efficient sulfur removal and metal recovery, promoting cleaner
energy production and environmental sustainability. Future research should focus on optimizing
electrochemical conditions and scaling up the process for industrial applications
Influence of rail foot modification on solidification stress of railway aluminothermic welding by casting simulation
No full textAluminothermic welding has been used to connect railway rails for over a century. This method has several advantages, including its versatility, the tightness of the weld it creates, and its ease of execution. To complete the procedure, no further power source is necessary. The NovaFlow & Solid CV software suite [1] was used to simulate casting thermite steel in the mold cavity or weld joint for the 49E1 rail. As a result, costly experimental techniques in industrial settings lead to ever-changing mould design. The design of the mould with the pouring system, which should ensure even pouring of thermal steel without turbulence, then even heat dissipation or cooling to obtain an appropriate micro and macro structure of steel free of internal and external defects, is one of several factors that contribute to a quality welded joint [2].
Initialy, a crude design of the casting was developed and compared with the real-life results [3], later, preheating was introduced to the simulation [4] and lastly, with the addition of side rails and mould to the casting simulation the design was close to real life conditions. With the final version of the mould design and simulation, stress and strain modeling were performed on the preheated model to provide a more complete understanding of how shrinkage is related to stress [5]. In this paper, the foot of the rail casting was modified to determine how best to eleveate the solidification stress, since the foot is the most compressed part of the rail during explotation. The steel used for simulation is commercial railway steel R260 or EN 1.0623, the molten metal flow was injected in a circle of 10 mm in diameter. Gravity casting was chosen for the filling parameters with a pressure height of 300 mm, making the flow 1.149 kg/s and the casting temperature was set at 2200 ºC. Unfortunately, due to the limitations of the software, it was not possible to move the burner heat source outside of the casting cavity (40 cm above the gating hole); however, the shape of the air flow and temperature were adjusted to reproduce real-life circumstances, but the position of the source remained below the divider.
Software programs are being used to simulate conventional casting procedures that may be used in the casting of thermite steel during the fabrication of welded railway connections in order to prevent costly and time-consuming industrial experimentation. Even though some concave shape modifications of the rail foot proved to be better than others, we will continue to work on developing the simulation conditions and, in the future, compare the most satisfactory with the final weld product experiments
Utilization of Aspergillus niger for nanoparticles synthesis from old flotation tailings Majdanpek (Serbia): A study via field emission scanning electron microscopy
No full textFlotation tailings, a residual product of mineral processing, present significant environmental challenges due to their composition and disposal requirements. This study investigates an innovative approach that harnesses Aspergillus niger for synthesizing nanoparticles from old flotation tailings sourced from Majdanpek, Serbia. Leveraging the biological activities of
microorganisms offers a sustainable strategy to convert waste into valuable nanomaterials. Under controlled conditions, Aspergillus niger was cultured in the presence of flotation tailings. Electron microscopy has played a pivotal role in elucidating the nanoparticle synthesis process and understanding the characteristics of the resulting nanomaterials. The imaging technique
revealed successful nanoparticle synthesis by Aspergillus niger from the flotation tailings, demonstrating a variety of shapes and sizes that highlight the versatility of the biological synthesis process. Detailed structural analysis of both the flotation tailings and the synthesized nanoparticles provided valuable insights into their formation mechanisms and compositions. This
approach not only demonstrates the feasibility of using old flotation tailings as a precursor material but also underscores the importance of sustainable resource management. The nanoparticles obtained hold promise for diverse applications in biomedical, environmental, optical, and quantum technologies, showcasing their potential to contribute significantly to
various fields
Application of MIPAR Software in the Identification and Quantification of Novel Antifungal Agents
No full textIn contemporary medicine, identifying and quantifying new antifungal agents is a critical challenge in combating fungal infections, which are increasingly prevalent and often resistant to existing treatments. Fluorine-containing compounds are known for their biological activities, and their antifungal properties are becoming increasingly significant in the context of fungal infection control. This study explores the application of MIPAR software, a powerful tool for data analysis in the fields of chemical and biomedical research. The discovery and evaluation of new antifungal agents and interpretation of complex biological data enables precise analysis of spectroscopic and other relevant data, thereby MIPAR enhances the efficiency of identifying potential candidates for new therapies. This work investigates the antifungal effects of ammonium fluoride against the pathogens Aspergillus niger and Aspergillus flavus, which are responsible for numerous diseases in humans and plants. Quantification of antifungal effects that impact growth rate and petri dish fungal surface coverage was performed using digital images analyzed with MIPAR software. The findings reveal significant differences in antifungal activity between Aspergillus niger and Aspergillus flavus. Our study revealed that Aspergillus niger was completely inhibited by ammonium fluoride, whereas the effects on Aspergillus flavus were less pronounced. These results highlight the potential of ammonium fluoride as an effective antifungal agent against Aspergillus niger, which may contribute to the development of new therapeutic strategies for fungal infection control. The use of digital imaging combined with MIPAR software represents an innovative approach to researching antifungal agents and can significantly enhance methodologies in this field. This study underscores how integrating software imaging technologies can improve research processes, reduce the time required for discovering new agents, and contribute to the development of more effective antifungal therapies. One of the future implementations for MIPAR software is using its machine learning capabilities and analyzing video frames as images form constant monitoring
Pelletization of fly ash for utilization in dynamic sorption processes
No full textFly ash, a byproduct of coal combustion in thermal power plants, has transitioned from industrial waste to a valuable technogenic raw material. Its alumino-silicate composition, porous structure, large specific surface area, and sorption activity make fly ash an efficient and low-cost sorbent for removing metal ions from acidic mine waters but only in discontinuous (static) systems. Its small particle size and poor hydraulic properties limit its application in continuous (dynamic) water treatment systems. This study aims to produce fly ash pellets with suitable properties for use as a sorbent in dynamic- column purification systems. By agglomerating fly ash with cement and plasticizer, pellets with enhanced mechanical properties such as compressive strength, impact strength, abrasion resistance, and disintegration time in water were developed. These pellets promise to improve the applicability and effectiveness of fly ash in dynamic water treatment processes, offering an economical and efficient solution for removing metal contaminants from wastewater
Geološke karakteristike ležišta zeolita “Toponica” kao sirovine za upotrebu u različitim oblastima ekologije
No full textZeolite was discovered in 1756 by F. Axel Frederic Cronsted, a Swedish mineralogist . He named them after the Greek words “zein” and “lithos”, which means “boiling
stone”. Zeolites are crystalline, hydrated aluminosilicates of alkaline and alkaline earth cations.
They possess an infinite three-dimensional crystal structure. Zeolites are characterized by
the ability to lose or receive wate. Also, they exchange some of their constitutional cations
without any major structural changes [1]. The most important characteristics of natural
zeolite minerals that enable their wide application in various areas of economic activities
are: ability absorption , processes ionic changes and catalysis . Natural zeolites are one of the
most economically significant groups of mineral raw materials due to their origin, physical
and chemical properties, as well as structural characteristics. There are numerous fields of
application of natural zeolites in ecosystems: in the removal of organic sulfur bound to oils,
in air purification from SO 2 , CO 2 and nitrogen oxides. Zeolite is a material that, due
to its properties, is used for removing cesium and strontium from soil contaminated with
nuclear waste, in water purification, in the field of agriculture, veterinary medicine, as a
construction material, etc.
The deposits and occurrences of zeolitic tuffs in Serbia are related to Tertiary lacustrine
volcanic-sedimentary and sedimentary complexes. They are related to the effusive activities
of dacitic, dacito-andesitic and andesitic magmas. In this regard, the most important are:
the Vranje, Toplic, Kruševac, Krivoreč, Sokobanj, Bogovin, West Moravian and Ibar basins,
the eastern part of the Great Moravian Trench as well as the Fruška Gora area
Efficient adsorption of pollutants from aqueous solutions by hydrochar-based hierarchical porous carbons
No full textThree-dimensional hierarchical porous carbons (HPCs) created through hydrothermal carbonization and the subsequent chemical activation of miscanthus were tested as adsorbents of Pb2+ and methylene blue from the aqueous solution. The HPC pore structure was customized using various hydrochar precursors obtained through a longer reaction time and by adding acetic acid. HPC obtained from hydrochar derived from acetic acid’s addition exhibited the highest specific surface area due to a larger micropore volume. This adsorbent proved to be the most efficient in removing lead from aqueous solutions. The Langmuir isotherm best described the lead adsorption process onto HPC with qm = 155.6 mg g−1 and the pseudo-second-order kinetic model. HPC obtained from hydrochar produced with a longer reaction time exhibited improved methylene blue adsorption properties. The pseudo-second-order kinetic model and the Freundlich isotherm best described the experimental data. The theoretical maximum adsorption capacity for methylene blue was 316.0 mg g−1. The type of hydrochar significantly impacted the yield and physical structure of HPCs, while having a lesser effect on the composition of surface functional groups. The results revealed the binding mechanism of each pollutant, highlighting the importance of biomass pretreatment on the structure of the resulting HPC and its effectiveness in water purification