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Engineering multimetallic oxides for enhanced oxygen evolution in green energy applications
No full textThis paper investigates the synthesis and characterization of potential catalysts for oxygen
evolution reactions (OER) using Ce, Y, Yb, Pr, Dy and Nd rare earth elements (REEs) in
combination with transition metals Co and Mn. Multivalent oxides were synthesized via
ultrasonic spray pyrolysis (USP) in a single-step process, utilizing metal salt precursors.
Structural and morphological analyses (XRD, SEM/EDS) confirmed the formation of
homogeneous oxide phases with controlled composition while electrochemical studies
(CV, LSV, PEIS, C-DC) demonstrated enhanced catalytic activity, excellent stability, and
favorable charge transfer kinetics in alkaline media. The results reveal that the engineered
multivalent oxides exhibit superior OER performance compared to conventional catalysts
attributed to the synergistic effects of REEs and transition metals in promoting electron
transfer and surface reactivity.
These oxides are designed for application either as standalone catalysts or as core
materials in core-shell systems where they serve as efficient supports to minimize the use
of expensive nobler metals such as iridium and tantalum. By strategically incorporating
these multivalent oxides as core structures, the nobler metal content can be significantly
reduced while maintaining high catalytic efficiency thus improving cost-effectiveness and
long-term sustainability. This approach aligns with the growing demand for scalable,
durable and resource-efficient electrocatalysts for energy storage and conversion
applications.
The findings of this study provide valuable insights into the design of next-generation
catalysts for green energy technologies including water electrolysis, metal-air batteries
and fuel cells. By leveraging the unique properties of multimetallic oxides this work
contributes to the development of efficient, low-cost and environmentally friendly
alternatives to traditional noble-metal-based OER catalysts ultimately supporting the
transition to cleaner and more sustainable energy solutions
Hydrothermal treatment for enhancing the performance of hierarchical porous carbon electrodes in supercapacitors
No full textInvestigating renewable, cost-effective, and environmentally friendly materials with rapid ion and electron transport, along with adjustable surface chemistry, is crucial for addressing energy production challenges today. Recently, three-dimensional biomass-based hierarchical porous carbons (HPCs) have gained significant attention due to their large surface area, beneficial pore structure, and diverse functionality. High-performance HPCs were produced through hydrothermal carbonization (HTC) of miscanthus followed by chemical activation of the feedstock. The pore structure of HPCs was tailored using various hydrochar precursors, achieved through extended reaction times and the addition of acetic acid.
The comprehensive characterization of the HPCs obtained through the proposed two-stage conversion process involved several techniques: elemental analysis, infrared (FT-IR) spectroscopy, scanning electron microscopy with energy-dispersive spectrometry, specific surface area analysis (SSABET), N2 adsorption-desorption isotherms and mercury intrusion porosimetry. Additionally, temperature-programmed desorption of CO2 from the precursors provided valuable insights into the chemical transformations that occur during these treatments, as well as the structure-function relationships of the resulting products. Electrochemical measurements, including cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic discharge tests, were conducted to assess the performance of the novel HPC electrodes. These measurements helped identify the most suitable miscanthus-based HPCs for use in supercapacitors
Aflatoxin B1 adsorption by bentonite and composites with chitosan and surfactant
No full textAflatoxins (AFs), a group of closely related, extremely toxic mycotoxins produced by some strains of the molds - Aspergillus flavus and Aspergillus parasiticus, can occur as natural contaminants of food and feeds worldwide. In the current study adsorption of aflatoxin B1 (the most toxic representative of AFs), was followed by bentonite – B (supplied from Getraco, d.o.o), B modified with commercial low molecular weight chitosan (sample B–Ch) as well as B–Ch modified with surfactant – hexadecyltrimethyl ammonium bromide (sample B–Ch–S). The initial raw material B and both composites were characterized by thermal analysis (TG/DTG) and determination of zeta potential. Results confirmed presence of chitosan in sample B–Ch and both chitosan and surfactant in sample B–Ch–S. Adsorption of aflatoxin B1 by B, B–Ch and B–Ch–S was investigated at different amounts of each adsorbent in suspension in buffer solution at pH 3 and 7, at fixed contact time (30 min). Results showed that for all materials, aflatoxin B1 adsorption increased with increasing the amount of each adsorbent in suspension and adsorption was practically independent of the solution pH. Although B already has high affinity to adsorb aflatoxin B1, the presence of chitosan and/or surfactant slightly increased adsorption of investigated mycotoxin at pH 3 and 7. Since both chitosan and surfactant have potential antibacterial activity, specifically composite B–Ch–S has a potential for a practical application as an animal feed additive
Balancing economic growth with environmental benefits in serbia's mining industry
No full textSerbia's mining industry is at a pivotal moment, navigating significant environmental challenges while
pursuing economic growth. The country's rich mineral deposits, including copper, gold, and lithium, present
substantial opportunities. However, the sector's development is hindered by outdated technology, limited
institutional capacity, and regulatory frameworks that complicate policy implementation aligned with EU
standards. Key legislative measures, such as the Law on Environmental Protection and the Law on Waste
Management, are in place, with ongoing efforts to establish a mining waste cadastre supported by EU funding.
Despite these efforts, challenges remain due to inadequate institutional capacity and poor interagency
coordination. The industry requires robust regulations, enhanced waste management infrastructure, and
strategic investments to overcome these obstacles. This research underscores the importance of balancing
economic development with environmental stewardship and social welfare to ensure the region's sustainable
growth and long-term prosperity
Exergy analysis and machine learning for enhanced eaf steel recycling
No full textThis study relies on exergy principles to analyze the sustainability of the steel re-cycling process in electric arc furnaces. Focusing on a balance between material and energy efficiencies, the research addresses the degradation of elements such as manganese and silicon from steel to slag phase. Machine learning techniques were employed to predict and optimize element distribution coefficients. By lever-aging HSC v.9 software, a detailed exergy analysis was performed, utilizing precise coefficients for element distribution in steel and slag, with energy consumption. The results demonstrate the potential of integrating exergy analysis and ma-chine learning to enhance the sustainability of steel production, aligning with circular economy principles
Health Risk Assessment and Accumulation of Potentially Toxic Elements in Capsella bursa-pastoris (L.) Medik
No full textCapsella bursa-pastoris (L.) Medik (C. bursa-pastoris) is an underexplored medicinal herb and
bioindicator of potentially toxic elements (PTEs). Its broad traditional utilization combined
with its high capacity for PTE accumulation may endanger human health. Herein, we
investigated the concentrations and mobility of PTEs (Ba, Co, Cr, Cu, Fe, Mn, Ni, Sr, and
Zn) in the urban soil–C. bursa-pastoris system and comprehensively assessed potential
health risks associated with exposure to contaminated soils, plant and herbal extracts.
Cu, Zn, Sr, and Mn were the most abundant in soils and predominantly phytoavailable.
The calculated values of the geo-accumulation index (Igeo) indicated moderate to heavy
Cu, Zn, and Sr contamination in the soil. C. bursa-pastoris demonstrated two strategies
for PTEs—the exclusion of Ba, Cr, Mn, and Sr, and the accumulation of Cu, Ni, Co, and
Fe. Principal Component Analysis (PCA) classified samples from four cities based on the
PTE levels in soils, plants, and herbal extracts. Although plant tissues contained elevated
levels of PTEs, the estimated daily intake (EDI), target hazard quotient (THQ), and lifetime
carcinogenic risk (LCR) demonstrated no significant health risks from consuming C. bursapastoris and its extracts. The obtained results indicated the higher sensitivity of children to
the hazardous effects of PTEs compared to adults. Extensive risk assessments of polluted
soils and inhabiting plants are crucial in PTE monitoring. This study underscored its
importance and delivered new insights into the contamination of medicinal herbs, aiming
to contribute to implementing safety policies in public health protection
Organic geochemical characterization of crude oils from the “PAL” oil field (SE Pannonian Basin, Serbia)
No full textThe most important oil fields in Serbia are located in the northern part of the country (N of river Danube) and belong to the southeastern part of the Pannonian Basin. This area is divided by the river Tisza into the western region of Bačka and the eastern Banat. Crude oils from the Banat were studied to a limited extent in the 1990s and in the 2010s, while data on oils from the Bačka region are largely missing, with the exception of the Velebit oil field. Therefore, oils from the western part of “PAL” oil field (near the Hungarian border) were investigated in this study to establish their origin, depositional environment, thermal maturity and age. For that purpose, physico-chemical parameters, distributions of biomarkers and aromatic hydrocarbons, as well as carbon isotopes were used.
API gravities of “PAL” samples vary between 28.4 and 32.4°, classifying them as light to intermediate oils. The pour point of the most samples is quite uniform (24–27 °C) and the content of asphaltenes is low (≤ 1%). The total acid number (≤ 0.30 mg KOH/g oil) ranks them as non-acidic oils. Dynamic viscosity at 50 °C ranges from 7.12 to 15.26 mPa·s and shows a slight increase with decreasing temperature up to the point of paraffin crystallization, where an abrupt spike is observed. The distillation characteristics of the “PAL” oils at atmospheric pressure are similar, with the average values for initial boiling point, end point and volume percent of pre-distilled oil being 80 °C, 350 °C and 61%, respectively. The carbon residue of the oils is uniform and averages at 3.51%.
n-Alkanes are predominant compounds in the chromatograms of whole oils, as well as in the total ion chromatograms of saturated fractions, showing that “PAL” oils are not biodegraded. The n-alkane distributions are similar in all samples and are characterized by equal abundances of odd and even members (Carbon Preference Index, CPI ~ 1). A domination of short-chain homologues is associated with Low vs. High Carbon Preference Index (LHCPI) values > 2.2 and Terrestrial-to-Aquatic Ratio (TAR) values 1.6 and gammacerane index (GI = 10×G/(G+C30 αβ hopane)) > 1. On the other hand, the presence of oleanane and taraxastane in all samples argues for a contribution of angiosperm derived terrestrial OM. The ternary diagram of relative abundances of regular C27-C29 αα(R) steranes and the values of Pr/n-C17 vs. Ph/n-C18 ratios indicate great similarity between “PAL” oils and also suggest a mixed aquatic-terrestrial origin (kerogen type II), with a domination of the former. This is further supported by the distributions of C19+C20, C21 and C23 tricyclic terpanes, which are characterized by an apparent dominance of C23 homologue and show the following trend: C23 > C19+C20 > C21. Stable carbon isotope compositions (δ13C) of the saturated and aromatic fractions plot “PAL” oils between the marine and terrigenous lines in the Sofer diagram. A negative δ13C slope was observed for n-alkanes from C17 to C19, whereas δ13C profiles of n-alkanes between C20 and C29 are relatively flat (with generally slightly increasing trend with increasing n-alkane chain length), implying a marine contribution to OM of the source rocks. The average δ13C values of C17-C29 n-alkanes (-27.4 to -26.6‰) differ by less than 1‰, confirming that “PAL” oils belong to the same genetic type.
The values of pristane/phytane (Pr/Ph) ratio 1 and the presence of β-carotane indicate deposition of OM under reducing conditions. Isorenieratane was detected in all samples, constituting 0.8–1.2% of the aromatic fractions. Although isorenieratane can be formed from β-carotene, the presence of its characteristic derivatives unambiguously indicates a contribution of green sulphur bacteria Chlorobiaceae to the precursor OM and photic zone of anoxia. The stratification of water column is also supported by the GI > 1. Alkylated 2-methyl-2-(4,8,12-trimethyltridecyl)chromans (MTTCs) occur in all samples. Distributions of MTTCs are quite uniform and characterized by a dominance of 5,7,8-trimethyl-MTTC (~32%) and 7,8-dimethyl-MTTC (~30%), while relative abundances of 8-methyl-MTTC and 5,8-dimethyl-MTTC were ~24% and ~14%, respectively. The values of MTTC ratio of ~0.30, associated with Pr/Ph < 0.85, indicate deposition of OM in “normal“ marine to mesosaline conditions, i.e. moderately increased salinity within the photic zone of the water column.
Hopane maturity ratios C30βα moretane/C30αβ hopane (0.12–0.14) and C31αβ(S)/C31αβ(S+R) (0.57–0.58) show almost identical values in all samples and attain their empirical equilibrium values (C30βα moretane/C30αβ hopane for Cenozoic oils). Sterane maturity ratios C29αα(S)/(C29αα(S)+αα(R)) (0.49–0.51) and C29ββ(R)/(C29ββ(R)+αα(R)) (0.48–0.49) confirm the uniform maturity of “PAL” oils. The same applies to methylphenanthrene maturity indices MPI 1 (0.61–0.66) and MPDF (0.42–0.45). Vitrinite reflectance, calculated from the values of C29αα(S)/(C29αα(S)+αα(R)) sterane ratio (0.80–0.83%) and MPDF index (0.79–0.84%), indicates a uniformly moderate maturity of “PAL” oils and their generation in the main stage of the oil window.
It is concluded that the oils from the “PAL” oil field are similar and belong to the same genetic type. The precursor OM originates from mixed marine/terrestrial sources, with a dominance of the former, and was deposited under reducing conditions. The oils were generated from source rocks in the main stage of the oil window, corresponding to the vitrinite reflectance of 0.80–0.84%. Since so far the source rocks have not been found in the Serbian part of the “PAL” oil field region, and according to the obtained results, it can be assumed that the studied oils derive from the Miocene source rocks located in the Szeged-Kiskunság Basin in south Hungary
Chemical composition of Karnabchul rangeland soils of different grazing intensities under simulated climate conditions
No full textSoils in Karnabchul semi-desert from sites of different grazing intensities are vulnerable to degradation in simulated climate conditions. Changes in of soils chemical composition, particularly through dissolution of cations and anions, shows that unsustainable gazing practices contribute to soil degradation and consequently reduce food security
Polystyrene-nickel interactions in soil: Implications for metal mobility, plant uptake, and human health
No full textThe coexistence of microplastics (MPs) and metals is ubiquitous in terrestrial ecosystems. However, their coupled effects on soil biota and human health remain unknown. The present study investigated the interactive impacts of polystyrene (PS)-nickel (Ni) contamination on Ni mobility in the soil-medicinal plant system and the associated health risks. A soil pot experiment was conducted with Capsella bursa-pastoris under six treatments: control (CK), PS alone (1 % w/w, PS), Ni at 50 and 500 mg kg− 1 (Ni50 and Ni500), and their combinations (Ni50 þPS, Ni500 þPS). The introduction of PS into soil promoted Ni transformation to the reducible soil fraction (F2) and increased its bioavailability by up to 81.2 % compared to treatments without MPs. The mechanism underlying Ni redistribution involved PS–soil associations that mask mineral binding sites and induce a “dilution effect,” whereby Ni loosely associated with PS surfaces became more mobile and bioavailable in the soil matrix. The most prominent increase was recorded in control soil (CK) and soil with 50 mg kg− 1 Ni (Ni50). PS addition to CK and Ni50 also stimulated Ni uptake by C. bursa-pastoris and increased the carcinogenic risk by 62.5 % compared to CK and by 28.6 % in Ni50 þPS compared to Ni50. Structural Equation Modeling (SEM) and Principal Component Analysis (PCA) confirmed that Ni bioavailability and transfer to and within the plant were strongly influenced by the PS presence. The findings of this study provided valuable insights into the toxic effects of PS-Ni exposure on the food safety of medicinal plants
Chitosan–Glucan Biopolymer Design: Extraction from Champignons with Improved Antioxidant and Antimicrobial Features
No full textIn this study, biopolymer chitosan–glucan from fruiting bodies of Agaricus bisporus (Cs-Agrif) was extracted and characterized as a sustainable alternative to commercial low molecular weight (LMW) chitosan obtained from crab shells (Cs-1). Cs-Agrif was prepared through an alkaline treatment process that included deproteination and deacetylation in the same step. The obtained sample was evaluated for its molecular weight, rheological behavior, degree of deacetylation (DD), crystallinity, and β-glucan and phenolic contents. Furthermore, the antioxidant properties of the prepared chitosan were determined under in vitro conditions using four spectrophotometric methods. Finally, its antimicrobial activity was tested against two pathogenic bacteria, one yeast, and mycotoxigenic fungi. Cs-Agrif had low molecular weight, of 45.70 ± 5.20 kDa, with pseudoplastic flow behavior. The degree of deacetylation was 92.7%. FT-IR and XRD analyses confirmed a chitosan-like structure and lower crystallinity in Cs-Agrif compared to pure commercial chitosan. The mushroom-derived chitosan contained β-glucans and phenols, indicating a chitosan–glucan complex. Antimicrobial assays showed low Cs-Agrif microbicidal concentrations (≤2.5 mg mL−1) for Escherichia coli, Enterococcus faecalis, and Candida albicans. The growth of Aspergillus flavus was significantly reduced after five days of incubation. The laboratory-prepared Cs-Agrif exhibited strong antioxidant activity at 5 mg mL−1, comparing to standards. Mushroom-derived chitosan–glucan biopolymer displays excellent physicochemical, antimicrobial, and antioxidant properties, confirming its potential use in biomedicine, food, and the pharmaceutical and cosmetic industries, among many others