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Recycling of nickel-cadmium batteries
No full textElektrode Ni-Cd akumulatora sadrže teške metale poput Ni, Cd i Co, koji se moraju
reciklirati u cilju rešavanja ekoloških problema. Istovremeno, Ni i Co koji se dobijaju u toku
procesa imaju i značaju ekonomsku vrednost i spadaju u strateški značajne metale (Critical Raw
Materials po EU klasifikaciji). U radu je prikazan literaturni pregled postupaka za reciklažu Ni-
Cd akumulatora sa posebnim osvrtom na luženje sumpornom kiselinom kao najčešće korišćenim
postupkom. Ova jedostavna hidrometalurška tehnologija je idealna za pogone manjeg i srednjeg
kapaciteta jer ne zahteva skupu opremu koja se koristi u pirometalurškoj tehnologiji koja
primenjuje karbotermalnu redukciju na visokoj temperaturi. U radu su prikazani i rezultati
fizičko-hemijske karakterizacije akumulatora nakon ručnog rasklapanja primenom ICP OES i
SEM EDS metoda.The electrodes of Ni-Cd batteries contain heavy metals such as Ni, Cd and Co, which must be
recycled to solve environmental problems. At the same time, Ni and Co obtained during the process
have significant economic value and belong to strategically important metals (Critical Raw Materials according to the EU classification). The paper presents a literature review of procedures for
recycling Ni-Cd batteries with a special reference to leaching with sulfuric acid as the most commonly used procedure. This simple hydrometallurgical technology is ideal for small and mediumcapacity plants because it does not require the expensive equipment used in pyrometallurgical technology that applies carbothermal reduction at a high temperature. The paper also presents the results of the physicochemical characterization of the battery after manual disassembly, performed by
ICP OES and SEM-EDS analyses
Assessment of Environmental Awareness of the Population of the Republic of Serbia in the Context of ISO 14001 Implementation
No full textZbog sve većeg broja ekoloških problema, očuvanje i zaštita životne sredine postaju od izuzetnog značaja. Međunarodna organizacija za standardizaciju (ISO) prepoznala je ovaj problem i 1994. godine razvila je seriju standarda ISO 14000. Ova serija obuhvata dve osnovne grupe standarda: one koji se odnose na sisteme upravljanja životnom sredinom i one koji se odnose na životni ciklus proizvoda. Standard ISO 14001 je generički standard i jedan je od najčešće implementiranih standarda sistema menadžmenta, a njegovi ključni principi uključuju podizanje svesti o ekološkim pitanjima i kontinuirano poboljšanje životne sredine. U okviru ovog rada sprovedeno je anketno istraživanje nivoa svesti stanovništva Republike Srbije o izvorima zagađenja i njihom uticaju na zagađenje. Većina ispitanika ocenila je nivo svesti stanovništva o pitanju životne sredune i trenutno stanje životne sredine u Srbiji kao loše. Na osnovu rezultata istraživanja, identifikovani su ključni izvori informacija o zagađenju životne sredine, a predložene su i odgovarajuće korektivne mere za unapređenje ekološke svesti i zaštite životne sredine.Due to an growing number of environmental problems, the preservation and protection of the environment have become extremely important. The International Organization for Standardization (ISO) recognized this issue and, developed the ISO 14000 series of standards in 1994. This series includes two main groups of standards: those related to environmental management systems and those concerning the product life cycle. The ISO 14001 standard is a generic standard and one of the most widely implemented management system standards. Its key principles include raising awareness of environmental issues and the continuous improvement of environmental performance. As part of this study, a survey was conducted to assess the level of public awareness in the Republic of Serbia regarding sources of pollution and their impact on environmental degradation. Most respondents rated the population’s awareness of environmental issues and the current state of the environment in Serbia as poor. Based on the research results, key sources of information about environmental pollution were identified, and appropriate corrective measures were proposed to improve ecological awareness and environmental protection
Toward Natural Wound Healing Therapy: Honey and Calendula officinalis Loaded κ-Carrageenan Films with Promising Hemostatic Potential
No full textBackground/Objectives: Efficient wound treatment embraces the management of four overlapping phases, starting with hemostasis, an immediate physiological response aimed at stopping bleeding from damaged blood vessels caused by skin injury. This paper proposes an innovative, nature-based hemostatic biomaterial designed to assist natural self-healing regenerative mechanisms. Methods: Light, transparent, and skin-adhesive films based on κ-carrageenan, meadow polyfloral honey, and Calendula officinalis flower extract were fabricated via solution casting. Comprehensive characterization revealed the physicochemical, structural, swelling, and barrier properties and the influence of each bioactive compound utilized for film preparation. Results: The samples subcutaneously implanted in Wistar rats induced vascularization, deposition of collagen, and orientation of collagen fibers while being fully phagocytosed and gradually biodegraded. The rat tail-cut model demonstrated that the films significantly reduced blood loss (0.1875 ± 0.0732 g) compared to the control (0.7837 ± 0.3319 g), and hemostasis was achieved notably faster (355.75 ± 71.42 s) than in the control group (704.25 ± 85.29 s). The rat liver punch biopsy model confirmed reduced blood loss (2.8025 ± 1.5174 g) and shorter time to hemostasis (303.25 ± 77.90 s) compared to the control (3.1475 ± 1.5413 g, 383.00 ± 36.53 s). Conclusions: The results indicate the great potential of the fabricated films as hemostatic wound dressings
Thermoresponsive pNIPAAM Hydrogels: eco-friendly synthesis and antibacterial properties
No full textIntroduction
Stimuli-responsive hydrogels have found applications in various fields due to their easily tunable properties. Among them, poly(N-isopropylacrylamide) (pNIPAAM) hydrogels are well-known for their biocompatibility and temperature-sensitive behavior. Above their lower critical solution temperature, which is close to human physiological temperature, pNIPAAM hydrogels undergo polymer network contraction, which lead to the release of encapsulated active substances. This property makes them highly suitable for controlled drug release applications. Previous studies have demonstrated that a system based on vitamin C and hydrogen peroxide can initiate polymerization of various monomers. In this study, a novel initiator system, utilizing peroxidase isolated from food waste material, hydrogen peroxide, and vitamin C, was employed for the polymerization of N-isopropylacrylamide. The use of peroxidase extracted from food waste aligns with circular economy principles by valorizing waste materials. Antibacterial properties of obtained pNIPAAM hydrogels with encapsulated gentamicin were further analysed.
Experimental
pNIPAAM hydrogels were synthesized using an initiation system composed of peroxidase isolated from food waste material, hydrogen peroxide, and vitamin C. The polymerization was conducted under ambient conditions, leading to successful hydrogel formation with reduced reaction time. The composition of synthesized pNIPAAM hydrogels were confirmed using Fourier-transform infrared spectroscopy (FTIR). The effects of peroxidase activity on hydrogel swelling in phosphate buffer pH 6.8 at different temperatures were investigated. Additionally, the antibacterial properties of these hydrogels were evaluated. Gentamicin was incorporated post-synthesis by immersing xerogels in an aqueous gentamicin solution. Two model bacteria were chosen for this analysis: Escherichia coli K12 (E. coli; Gramm negative) and Staphylococcus capitis (S. capitis; Gramm positive). Fresh cultures of both bacteria were diluted to the same optical density (OD600=0.1) prior starting the experiment. Two mL of bacteria culture was added in falcons with samples. After 1 h, OD of all samples were measured and 5 μL of each suspension was seeded onto agar in 24 well plates. Measurement of OD and bacteria seeding was performed also after 8 h and 24 h of incubation with hydrogel samples. Control was bacterial culture starting at OD600=0.1 without any contact with tested samples during 24 h. After seeding, petri dishes were placed at 37 °C and they were imaged 24 h later using light microscope. The pNIPAAM hydrogel samples were UV sterilized prior the analysis.
Results
The composition of the synthesized pNIPAAM samples was confirmed by the presence of characteristic peaks of poly(N-isopropylacrylamide) in the FTIR spectra of all samples: the peak at 1524 cm⁻¹ corresponding to bending vibrations of the -NH group, the peak at 1639 cm⁻¹ corresponding to C=O stretching vibrations, and the peak at 3281 cm⁻¹ corresponding to N-H vibrations. The equilibrium swelling ratio of the hydrogels decreased with increase in temperature, confirming the thermoresponsive nature of pNIPAAM. Higher peroxidase activity led to increased swelling ratios. The pNIPAAM hydrogels were effective against E. coli after incubation of 24h
FT-IR spektri, mineralni sastav i biološka aktivnost liofilizovanih ekstrakata otpada Fumaria officinalis
No full textPlant waste valorisation offers a sustainable approach to extract secondary metabolites with therapeutic, antioxidant, and cosmeceutical potential. Fumaria officinalis (fumitory), a traditionally used medicinal plant, contains various biologically active secondary
metabolites, but the influence of different extraction methods on its phytochemical yield, mineral composition, and bioactivity
remains underexplored. Four extraction techniques, i.e. maceration (M), heat-assisted extraction (HAE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), were applied to obtain fumitory extracts. The extraction yield, mineral
composition, phytochemical functional groups (Fourier Transform Infrared analysis - FT-IR spectroscopy), antimicrobial potential,
hemolysis inhibition under thermal and hypotonic stress, and sun protection factor (SPF) were assessed. The extraction technique
significantly influenced the extraction yield, which ranged from 17.24% (M) to 37.98% (MAE). Potassium was the most abundant macronutrient (271.56–400.37 g/kg), while all micronutrient concentrations were below 1 g/kg. The FT-IR analysis revealed functional
groups typical of phenolics, alkaloids, and proteins, confirming the complex chemical structure of the extracts. All of the extracts
exhibited antimicrobial activity against Staphylococcus aureus and Enterococcus faecalis, but not against Gram-negative bacteria or
fungi. The UAE and MAE extracts showed superior protection against heat-induced hemolysis (up to 70.4% inhibition at 0.25 mg/
mL), and all the extracts demonstrated moderate, dose-dependent protection in hypotonic conditions. The SPF analysis revealed
UV-B absorbance across 290–320 nm, with the UAE extract at 100 µg/mL achieving the highest SPF value (1.66 ± 0.01). The study
highlights the significantly influence of the extraction method on the physicochemical and biological properties of F. officinalis extracts. Ultrasound-assisted extraction and MAE were the most effective in obtaining extracts with enhanced bioactivity. These findings support the potential application of fumitory extracts in natural therapeutics and cosmetic formulations. Future work should
focus on isolating specific active constituents and evaluating efficacy for pharmaceutical and cosmeceutical applications in terms of
wound-healing or anti-aging activities in novel cell models related to disorders, infections, wounds, burns, or skin ageingEksploatacija biljnog otpada u cilju ekstrakcije sekundarnih metabolita sa terapeutskim, antioksidativnim i kozmetičkim potencijalom, podržava principe održivog razvoja. Fumaria officinalis (dimnjača), tradicionalno korišćena lekovita biljna vrsta, sadrži različite biološki aktivne sekundarne metabolite, ali uticaj različitih metoda ekstrakcije na prinos ekstrakcije, mineralni sastav i bioaktivnost ove biljke još uvek nije dovoljno istražen. Četiri ekstrakcione tehnike, tj. maceracija (M), ekstrakcija na povišenoj temperaturi (HAE), ekstrakcija ultrazvučnim talasima (UAE) i ekstrakcija mikrotalasima (MAE), primenjene su za dobijanje ekstrakata dimnjače. Određeni su prinos ekstrakcije, mineralni sastav, karakteristične funkcionalne grupe (tehnika infracrvene spektroskopije sa Furijeovom transformacijom, FT-IR), antimikrobni potencijal, inhibicija hemolize izazvane termalnim i hipotonim stresom, kao i faktor zaštite od sunca (SPF). Tehnika ekstrakcije značajno je uticala na prinos ekstrakcije, koji je varirao od 17,24% (M) do 37,98% (MAE). Kalijum je bio najzastupljeniji makronutrijent (271,56–400,37 g/kg), dok su koncentracije svih mikronutrijenata bile ispod 1 g/kg. FT-IR analiza je pokazala prisustvo funkcionalnih grupa karakterističnih za fenole, alkaloide i proteine, potvrđujući složen hemijski sastav ekstrakata. Svi ekstrakti su pokazali antimikrobnu aktivnost prema bakterijama Staphylococcus aureus i Enterococcus faecalis, ali ne i protiv testiranih Gram-negativnih bakterija ili gljiva. UAE i MAE ekstrakti su pokazali visok nivo zaštite eritrocita od hemolize izazvane termalnim stresom (do 70,4% inhibicije pri koncentraciji od 0,25 mg/mL), dok su svi ekstrakti ispoljili umerenu i dozno-zavisnu zaštitu eritrocita u hipotoničnim uslovima. SPF analiza je pokazala UV-B apsorpciju u opsegu od 290–320 nm, pri čemu je UAE ekstrakt u koncentraciji od 100 µg/mL postigao najvišu SPF vrednost (1,66 ± 0,01). Studija pokazuje da metoda ekstrakcije značajno utiče na fizičko-hemijska i biološka svojstva F. officinalis ekstrakata. UAE i MAE su se pokazale kao najefikasnije metode za dobijanje ekstrakta sa najvećim biološkim potencijalom. Ovi rezultati podržavaju potencijalnu primenu ekstrakata dimnjače u prirodnim terapeutskim i kozmetičkim formulacijama. Buduća istraživanja treba da se fokusiraju na izolaciju specifičnih aktivnih jedinjenja i procenu njihove efikasnosti u farmaceutskim i kozmetičkim formulacijama, posebno u kontekstu zarastanja rana i delovanja protiv starenja kože, na novim ćelijskim modelima koji simuliraju oboljenja, infekcije, rane, opekotine i starenje kože
Comprehensive Assessment of Heavy Metal(loid) Pollution in Agricultural and Urban Soils near an Oil Refining Facility: Distribution Patterns, Source Apportionment, Ecological Impact, and Probabilistic Health Risk Analysis
No full textThis study investigated the spatial distribution of HMs in agricultural and urban soils near the largest oil refining complex in Serbia, identified pollution sources, and assessed ecological and human health risks. A large fraction of soil samples showed elevated Hg (40% of samples), Pb (53%), Cd (90%), and As (93%) concentrations compared to the background levels. Hotspots for Pb, As, Hg, Cd, and Zn were observed in the industrial area, indicating significant anthropogenic input. Multivariate analysis, including PMF, revealed four contamination sources: emissions from the oil refining industry, agricultural activities, traffic emissions, and natural background. The pollution indices mostly fell into the moderate pollution range, with As, Hg, and Cd showing the highest enrichment. The potential ecological risk index (RI) indicated that about one-third of the samples had moderate ecological risk and determined a major RI hotspot near the refinery. The health risk assessment identified As and Cr as the largest contributors to non-carcinogenic risk, although the average HI was below one. Monte Carlo simulation confirmed that adults and children had negligible health risks at the 95th percentile and highlighted exposure frequency and body weight as the most influential exposure parameters. Based on source-specific risk, the oil refining industry emissions had the highest impact on HI and TCR values
Melting Temperatures and Electrical Conductivity of Lead-Free Soldering Alloys for Filler Materials
No full textLead-based filler metals were used for soldering for many years, but they are now being gradually replaced by lead-free materials, usually alloys. Contemporary alloys commonly contain metals such as antimony, bismuth, copper, indium, tin, zinc, silver, and gallium. Some of their properties still need to be studied in more detail. A good solder joint must create a reliable electrical connection with high conductivity, having suitable thermal properties at the same time. In addition, soldering materials must meet other requirements such as good fluidity and resistance to corrosion. Mechanical strength is usually not a top priority, except in portable or handheld devices, where the joints need to withstand impacts from drops and shocks. Pure metals are seldom used as filler materials in soldering, as alloys are generally preferred due to their broader range of beneficial properties. In this paper, we take a closer look at several key properties of the soldering alloys
Heavy metal(loid) hazards in landfill groundwater: An assessment using self-organizing maps and 2D Monte Carlo modeling
No full textLandfill-derived heavy metal(loid) (HM) contamination of groundwater is a pressing environmental issue, yet comprehensive assessments in such settings remain limited. This study investigated HM pollution, hydrogeochemistry, irrigation suitability, and corrosion/scaling potential in groundwater surrounding the Vinča municipal solid waste landfill, one of the largest in Southeast Europe. Concentrations of Fe and Mn exceeded drinking water standards in 50 % and 77 % of samples, respectively, while other metals remained within permissible limits. The dominant hydrochemical facies was Ca-Mg-HCO3, shifting toward Ca-Mg-SO4-Cl near the landfill. Irrigation quality was generally acceptable, with sodium adsorption ratio (SAR) and sodium percentage (%Na) ranging from 0.42 to 14.1 and 5.8–84.9 %. Scaling indices indicated a tendency toward scale formation, particularly in the northeastern sector. Self-organizing maps (SOM) classified samples into four distinct clusters, corresponding to different HM sources. The heavy metal pollution index (HPI) suggested low to moderate pollution, primarily driven by Cd and Hg. Combined two-dimensional Monte Carlo simulation (2D MCS) and multiple linear regression identified threshold concentrations for Cd (1.8 μg/L) and Hg (0.11 μg/L) necessary to maintain HPI values within the low-pollution category. This integrated approach offers a framework for establishing protective concentration limits to improve groundwater management
Design and Development of Sustainable Geopolymers Based on Fly Ash, Slag, and Diatomaceous Earth: A Chemometric Approach
No full textThe burning of coal in thermal power plants throughout Serbia produces significant amounts of industrial waste, primarily in the form of fly ash, boiler ash, and slag. Given their annual production, availability, and fine grain structure, it is necessary that sus-tainable strategies are developed for their reuse, instead of depositing them directly in landfills. In this research, the possibility of using fly ash, slag, and diatomaceous earth as raw materials for the synthesis of geopolymers at low temperatures was examined, in order to replace cement in construction materials, with the aim of reducing carbon dioxide emissions. Special emphasis was put on the effect of addition of organic macromole-cules—polyvinyl alcohol (PVA), chitosan, and starch—upon the structure and mechanical properties of the obtained materials. In addition, the behavior of the materials with regard to the leaching of heavy metals in different environmental conditions was examined. Chemometric methods of multivariate analysis were used to examine the correlations between the obtained physical–chemical parameters, while the dependence of me-chanical properties on the composition of the raw mixture was analyzed using the Mixture Design of Experiments method. The results obtained indicate that the examined waste materials have potential to be used as an environmentally friendly alternative to cement. The addition of PVA and chitosan had a positive effect on the mechanical properties of the geopolymers, with the highest strength achieved in formulations based solely on fly ash, containing 2.5% PVA, which reached 12.6 MPa. It was also shown that the addition of 30% diatomaceous earth increases the density and compressive strength of the material, while reducing the number of microcracks present in its structure, with a compressive strength of 13 MPa
Temperature-Related Reproductive Challenges in the Plum Cultivar ‘Timočanka’
No full textThe European plum cultivar ‘Timočanka’ (Prunus domestica L.) is valued for its large, high-quality fruits, but it exhibits irregular bearing. To address this issue, the present study was conducted over two consecutive years, with significantly higher average daily temperatures during flowering in the first year. The study comprised in vitro pollen germination, quantitative analysis of pollen tube growth in vivo, and initial and final fruit set under three pollination treatments (open-, self-, and cross-pollination with the cultivars ‘Čačanska Lepotica,’ ‘Čačanska Rodna,ʼ and ‘Stanleyʼ), along with the assessment of flowering phenophase, embryo sac viability in unpollinated flowers, and fertilization success in open-pollinated flowers within 21 days of full bloom. Our results suggest that ‘Timočanka’ has low pollen viability and limited self-fertility, requiring compatible pollenizers that bloom simultaneously for reliable production. The best synchronization of reproductive phases occurred with ‘Čačanska Lepotica’ and ‘Čačanska Rodna.’ Cross-pollination with ‘Čačanska Lepotica’ resulted in the highest values of pollen tube growth parameters, while ‘Čačanska Rodna’ induced the highest fruit set. Faster pollen tube growth and a quicker decline in the functional stages of embryo sacs were observed in the first year, along with improved male–female synchrony and higher number of fertilized embryo sacs. When examining individual pollination variants, specific contrasting trends emerge. These patterns suggest differing levels of resilience to environmental changes among various pollination treatments, further highlighting the complex interactions between pollination dynamics and temperature