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A comprehensible approach to enhanced photocatalytic efficiency of boron-doped carbon quantum dots: organic dyes compared to herbicides
No full textBoron-doped carbon quantum dots (B-CQDs) have emerged as promising photocatalysts due to their tunable electronic properties, strong visible light absorption, and high stability. This study investigates the photocatalytic activity of B-CQDs for the degradation of organic dyes, such as rose bengal, and herbicides, including fluroxypyr, clomazone, and Quinmerac, under UV light irradiation. The research aims to elucidate the mechanisms governing the photocatalytic efficiency of B-CQDs and to compare their performance in degrading structurally diverse pollutants. The results indicate that B-CQDs exhibit significantly higher photocatalytic activity toward organic dyes compared to herbicides. This enhanced performance is attributed to the strong adsorption of dyes on the B-CQD surface, the susceptibility of their chromophores to reactive oxygen species (ROS), and the potential synergistic photosensitization effects of the dyes. In contrast, the chemical stability and weaker adsorption of herbicides limit their degradation efficiency, despite the ROS generation capabilities of B-CQDs. These findings highlight the potential of B-CQDs as efficient photocatalysts for environmental remediation, particularly for the treatment of dye-laden wastewater. However, the study also emphasizes the challenges associated with degrading more stable pollutants like herbicides, pointing to the need for further optimization of catalyst design and process conditions. This research advances understanding of B-CQD photocatalysis and offers insights into their selective environmental application
Cu and Ag Deposited on Pristine and Plasma-Treated g-C₃N₄: Noble vs. Non-Noble Metal Photocatalysts for Cr(VI) Reduction
No full textPhotocatalytic reduction using semiconductors offers a cost-effective, sustainable way to remove toxic Cr(VI) from industrial effluents. Graphitic carbon nitride (g-C3N4, CN) is a promising option due to its chemical stability, facile synthesis, and visible light activation enabled by its moderate band gap (2.7 eV). However, its photocatalytic efficiency is limited by high carrier recombination and low utilization of visible light. The combination of CN with metal nanoparticles (NPs) forms metal-semiconductor heterostructures (MS) that enhance charge separation via the Schottky barrier and improve visible light absorption via the localized surface plasmon resonance (SPR) effect. The effective creation of MS heterostructures requires strong contact between CN and metal NPs. We assumed that plasma treatment, a widely used method to modify photocatalyst surfaces, could improve NP adhesion by introducing functional groups, altering morphology, and creating defects. The result would be enhanced stability and performance of CN-based heterostructures.
This study explores the chemical reduction deposition of Ag and Cu on pristine and plasma-treated CN. Bulk CN was synthesized by thermal polymerization of urea, while CuCl2 or AgNO3 were used as NPs precursors. The properties of the photocatalysts were studied by XRD, FTIR, FESEM, EDS, TEM, PL and DRS analyses. Characterization revealed enhanced visible light absorption (DRS) and reduced carrier recombination (PL). A greater amount of Ag/Cu was deposited on the plasma-treated CN (EDS), with Ag-based samples showing superior and Cu-based samples showing lower photocatalytic performance compared to the pristine CN
Carp Scales Modified with Cerium Oxide Nanoparticles as a New Bio-Adsorbent for Arsenic and Chromium Separation from Water
No full textDifferent treatments of fish scales from carps (Cyprinus carpio) (FS)—mechanical milling, modified with cerium dioxide (CeO2) nanoparticles and controlled carbonization of FS and modification with CeO2—were applied to obtain FS, FS-CeO2 and CFS-CeO2 bio-adsorbents. The synthesized adsorbents were used for As(V) and Cr(VI) oxyanion separation from water. Porosity and the amount of CeO2 nanoparticles deposition were controlled using different experimental conditions. Response surface methodology (RSM) was used to select optimal parameters for adsorbent synthesis to obtain the highest adsorption capacity. The structural and surface characteristics of the synthesized adsorbents were examined using FTIR, XRD and SEM techniques. The efficiency of pollutant removal was analyzed in terms of varying experimental conditions: the mass of adsorbent, pH, temperature and contact time. RSM was also used to optimize adsorption and desorption processes. The adsorption data, obtained at 25, 35 and 45 °C, were processed using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm and Van’t Hoff thermodynamic models. The FS-CeO2 bio-adsorbent showed good adsorption capacities of 92.61 and 65.50 mg g−1 for As(V) and Cr(VI) ion removal, respectively, obtained by using the Langmuir model. Thermodynamic parameters proved that adsorption was a viable, spontaneous and endothermic process. The results from kinetic modeling indicated that both adsorbate and surface functional group concentration determine overall kinetic law with the highest participation of intra-particle diffusion resistance to pollutant transport. Exceptional adsorption and desorption performances of FS-CeO2 in conjunction with the bio-based origin of synthesized adsorbents offer valuable alternatives for the remediation of polluted water
Structural, morphological, mechanical and thermal properties of PMMA/SiC composites
No full textIn this study, silicon carbide (SiC) microfibers were added as reinforcement to improve the thermomechanical properties of
poly (methyl methacrylate) polymer, PMMA, since this type of composite has not been explored well enough so far. The aim
of this study is to obtain PMMA/SiC composite materials with superior mechanical and thermal qualities out of the starting
material, which are customizable for potential applications in flexible electronics as protective/buildable films. Thin PMMA
composite films with 0.5 wt.% and 1.0 wt.% SiC microfibers regarding PMMA were made by casting. The Differential
Scanning Calorimetry (DSC) analysis verified that the PMMA/SiC composites achieved greater thermal stability than the
neat PMMA due to the presence of SiC microfibers. The glass transition temperatures of PMMA/0.5 wt.% SiC and PMMA/
1.0 wt.% SiC films were around 2.4°C and 3.5°C higher, respectively, in comparison with the pure PMMA film. The results
also showed that the PMMA films with 0.5 wt.% and 1.0 wt.% SiC reinforcement had 17.9% and 55.6% improvement in
microhardness, respectively, compared to the neat PMMA film. The Atomic Force Microscopy (AFM) characterization of
the PMMA composite films was also carried out. The addition of SiC microfibers to the PMMA polymer matrix also caused
an increase in the roughness of the PMMA/SiC films. The average roughness values of the PMMA/SiC films were approximately 3.9 (with 0.5 wt.% SiC) and 13.7 (with 1.0 wt.% SiC) times larger than those obtained for the pure PMMA film.
AFM in semi-contact operation mode was used to obtain 3D images of Vickers indents on the surface of PMMA and PMMA/
SiC composite films. Both optical and atomic force microscopy approved the presence of pile-up effect after the indentation
of PMMA films
Source apportionment and probabilistic health risk assessment of polycyclic aromatic hydrocarbons in sediment from an urban shallow lake
No full textPolycyclic aromatic hydrocarbons (PAHs) in sediment from urban shallow lake Bubanj (Serbia) were investigated in terms of their concentration, distribution, and potential effects on the environment and human health. The concentration of 16 PAHs (ΣPAHs) ranged from 24.4 to 107 ng/g dw. Low-molecular-weight PAHs (2- and 3-aromatic rings) were dominant, accounting for 71% of the total. Multivariate statistical analyses revealed that the main source of PAHs was the incomplete combustion of organic sources. Diagnostic ratios and positive matrix factorization (PMF) methods further indicated that combustion of organic matter and petroleum leakage were the dominant sources. The toxic equivalent quantity (TEQ) of ΣPAHs varied from 0.5 to 17.6 ng-TEQ/g-dry. BaP had the highest contribution to TEQ, followed by Ant, DahA, and BaA, with respective shares of 74.3%, 6.4%, 5.6%, and 5.3%. Dermal contact and ingestion were the primary exposure routes for PAHs, whereas inhalation posed negligible cancer risk. The incremental lifetime cancer risk (ILCR) values for adults were in the range of 3.9 × 10−9–1.4 × 10−7 and for children 5.3 × 10−9–1.9 × 10−7, indicating negligible carcinogenic health risks. Monte Carlo simulation showed that ILCR values for adults and children remained below the permissible limit of 1.0 × 10−6, even at the 90th percentile
High-entropy spinel oxides: Self-propagating synthesis and densification by spark plasma sintering
No full textThe self-propagating room temperature method was utilized to synthesize high-entropy spinel oxides (HESOs): (Co,Cr,Fe,Mn,Ni)3O4-δ, (Mg,Cr,Fe,Mn,Ni)3O4-δ, (Mg,Co,Fe,Cr,Mn)3O4-δ, (Mn,Zn,Fe,Ni,Cr)3O4-δ, and (Co,Mn,Zn,Fe,Cr)3O4-δ. After thermal treatment at 1000 °C, XRD analysis confirmed their single-phased spinel structure. Densification by spark plasma sintering was successfully used for the first time on HESOs, resulting in relative densities from 94 % to 99 % while retaining the spinel structure. SEM/EDS mapping displayed a homogenous, dense microstructure with minimal porosity. (Mn,Zn,Fe,Ni,Cr)3O4-δ displayed the highest bending strength (171.5 MPa) and Young’s modulus (188 GPa). (Mg,Co,Fe,Cr,Mn)3O4-δ demonstrated the highest hardness (8.8 GPa), while (Mg,Cr,Fe,Mn,Ni)3O4-δ exhibited the highest indentation fracture toughness (1.5 MPa m–1/2). The lowest thermal diffusivity (0.67 – 0.51 mm2 s–1) was recorded for (Co,Mn,Zn,Fe,Cr)3O4-δ, while (Co,Cr,Fe,Mn,Ni)3O4-δ, had the highest thermal diffusivity (0.82 – 0.58 mm2 s–1). The study demonstrated a simple and efficacious method of synthesizing and densifying HESOs with structural, mechanical, and thermal properties favourable for different applications
Anti-Inflammatory and Immunomodulatory Properties of Inorganic Fullerene-Like Tungsten Disulfide Nanoparticles in the Culture of Human Peripheral Blood Mononuclear Cells
No full textTungsten disulfide (WS2) nanoparticles have emerged in the biomedical field as potential theranostic agents due to their unique properties, including biocompatibility. However, their impact on the immune response remains unexplored. This study aimed to evaluate the effects of inorganic fullerene-like WS2 (IF-WS2) nanostructures on human peripheral blood mononuclear cells (PBMCs) in vitro. The study investigated several parameters to evaluate the effects of IF-WS2 nanoparticles. Cytotoxicity was assessed by measuring cell viability, apoptosis, and necrosis. Internalization of IF-WS2 by PBMCs was analyzed using morphological and flow cytometric techniques. Proliferation was studied in CellTrace Far Red-prestained total PBMCs stimulated with phytohemagglutinin (PHA) and in isolated T cell cultures stimulated with CD3/CD28-coated beads. Additionally, the production of cytokines and chemokines was measured in culture supernatants of total PBMCs and T cells. IF-WS2 nanoparticles were non-cytotoxic up to a concentration of 200 µg/mL. Concentrations ≥25 µg/mL inhibited PHA-stimulated PBMC proliferation but did not affect T cell proliferation. Morphological and flow cytometric analysis demonstrated dose- and time-dependent internalization of IF-WS2 by macrophages. Additionally, IF-WS2 significantly reduced the production of pro-inflammatory cytokines (IL-1β, TNF-α, IL-8, MCP-1, and GRO-α) in PHA-stimulated PBMCs. Th1, Th17, and Th21 cytokines were downregulated, while Th2, Th9, and T regulatory cytokines were upregulated. In conclusion, this study demonstrated for the first time that pristine IF-WS2 nanoparticles, at non-cytotoxic concentrations, exhibit notable anti-inflammatory and immunomodulatory properties on activated PBMCs in vitro
Study of a Sensitive and Selective Electrochemical Biosensor for Glucose Based on Bi2Ru2O7 Pyrochlore Clusters Combined with MWCNTs
No full textThe development of sensitive, selective, and reliable glucose biosensors remains
a persistent challenge in clinical diagnostics. In this study, we exploited the advantageous
(electro)catalytic properties of bismuth ruthenate (Bi2Ru2O7) pyrochlore clusters, known
for their high surface activity and metallic-like conductivity, and the favorable physicochemical properties of multi-walled carbon nanotubes (MWCNTs) by combining them with
glucose oxidase (GOD) in a sensitive and selective disposable glucose biosensor. The integration of Bi2Ru2O7 enabled an enhanced and more reproducible response of the biosensor
along with fast and improved communication between the supporting electrode and the
upper biosensing layer. The architecture of the biosensor involves the deposition of an
MWCNT layer on a ferrocyanide-modified screen-printed carbon electrode (FCN-SPCE),
followed by the application of a biorecognition layer including GOD and Bi2Ru2O7 clusters.
The voltammetric biosensor showed excellent electroanalytical performance, capable of
detecting low glucose concentrations with a detection limit of 40 µM along with a linear
response across the examined concentration range of 1.0–20.0 mM. The biosensor exhibited
good reproducibility with a relative standard deviation (RSD) of 1.2% and interference-free
operation against several of the most common interfering compounds. The practical applicability of the biosensor was demonstrated by the determination of glucose in a real serum
sample spiked with different concentrations of glucose
Towards zero carbon emissions: Electrification and decarbonization of an ethylene Plant's utility system
No full textThe industrial sector faces significant challenges in decarbonization, within the petrochemical industry being a major contributor to global greenhouse gas (GHG) emissions. Ethylene, a key feedstock for polymers such as polyethylene (PE) and polyethylene terephthalate (PET), is primarily produced through steam cracking, a process heavily reliant on fossil fuels and responsible for substantial CO₂ emissions. This study introduces a systematic approach to retrofit steam utility system for an ethylene production plant, featuring the integration of hydrogen-fired boilers, electric superheaters, electric boilers and supplementary turbines linked to electrical generators. Powered entirely by renewable energy sources, this innovative electrification strategy is designed to enhance operational efficiency while optimizing both capital and operating costs. By adopting renewable energy options within the utility system, the proposed design significantly reduces the plant's carbon footprint, contributing to a more sustainable and environmentally responsible ethylene production process