Search Results (479)

Plating on Plastics (PoP) requires specific surface pre-treatment steps to enable metallization. The conventional PoP industry utilizes hexavalent chromium (toxic, carcinogenic) and palladium (critical raw material) for surface etching and activation, respectively, raising significant health, environmental, and economic concerns. This work is based on a new Cr⁶⁺-free and Pd-free PoP technology that uses piranha (H₂O₂-H₂SO₄) solutions for surface etching, nickel salts for activation, and NaBH₄ for reduction, ultimately forming metallic nucleation sites for downstream electroless plating and electroplating. A comprehensive modeling approach was developed to simulate and predict unit operation performance (reaction kinetics and yields) and material properties (contact angle and adhesion) across processing stages of the new technology. State-of-the-art and data-driven modeling revealed the combinatorial relationships among process performance, the achieved properties and the different settings of process operating conditions. The results also highlighted capabilities for tuning all processes over a range of conditions, reaching desired product specifications (adhesion and thickness). The models were constructed as a Decision Support Tool (DST) serving economic, environmental, safety and Safe and Sustainable by Design (SSbD) objectives. The DST can be used through a user-friendly interface that enables the insertion of user-defined inputs and monitoring of optimization results. Full article

The development of cost-effective and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) is pivotal for sustainable hydrogen energy production. Herein, coaxial electrospinning one-dimensional (1D) hollow carbon nanofiber (HCNF) in situ-grown MoS₂/CoS₂ nanosheets were impregnated with a NaBH₄ solution to obtain a HCNF-loaded sulfur-vacancy-rich MoS₂/CoS₂ heterojunction nanosheets catalyst of Vs-MoS₂/CoS₂-0.1@HCNFs. The unique hollow architecture afforded by electrospinning facilitates rapid electron transport and effectively mitigates the agglomeration of active 2D nanosheets, ensuring maximum exposure of catalytic sites. Furthermore, NaBH₄ impregnation introduces abundant sulfur vacancies into the heterojunction lattice, synergistically modulating the electronic structure. Benefiting from the structural advantages of the electrospun framework and defect engineering, the optimized catalyst (Vs-MoS₂/CoS₂-0.1@HCNFs) exhibits superior HER activity in 1.0 M KOH, requiring an overpotential of only 115 mV to achieve a current density of 10 mA cm⁻², along with a low Tafel slope of 83.3 mV dec⁻¹ and excellent long-term stability. This study demonstrates the efficacy of electrospinning in designing high-performance, self-supported electrocatalysts for sustainable energy applications. Full article

The nickel-derived metal–organic framework (MOF), Ni-BTB, synthesized from 4,4′,4″-benzene-1,3,5-tribenzoic acid (H₃BTB), was investigated as a multifunctional platform for enhanced energy applications including production and storage. In catalytic hydrogen generation by NaBH₄ hydrolysis, Ni-BTB attained a hydrogen generation rate (HGR) of 4640 mL H₂/g•min with 1 mg of catalyst, with an activation energy of 76.44 kJ/mol. Under optimized reaction conditions (60 °C, 20 mg catalyst, and 1 g NaBH₄), the HGR increased to 9542 mL H₂/g•min, while exhibiting high recyclability throughout four successive cycles. As a supercapacitor electrode, Ni-BTB achieved a specific capacitance of 156 F/g at 1 A/g and showed remarkable cycling stability, maintaining its capacitance after 10,000 charge–discharge cycles. Furthermore, Ni-BTB exhibited exceptional electrocatalytic activity for oxygen evolution reaction (OER), requiring only 106 mV overpotential to achieve 10 mA/cm², offering a time-of-flight (TOF) of 0.0585 s⁻¹ and demonstrating significant operational longevity of at least 12 h. These findings underscore Ni-BTB as a durable, reusable, and adaptable material for hydrogen production, energy storage, and electrocatalytic applications. Full article

In this study, the in situ solvothermal synthesis of a copper-based metal–organic framework (Cu-BTC MOF) into two porous ceramic substrates with a 10 cm diameter and 2 cm thickness was reported. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, diffuse reflectance spectroscopy (DRS), Tauc plot analysis, optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were the techniques that were utilized to verify the formation and incorporation of the MOF into ceramics (two samples, with different SiO₂ particles; 500 µm (Ceramic 1), and 150 µm (Ceramic 2)). The synthesized Cu-MOF exhibited a crystalline structure. Both the composites and the Cu-MOF exhibited visible-light absorption, with optical band gaps of 2.5 eV and 2.4 eV, respectively, as determined by DRS. TEM images demonstrated that crystalline MOF domains were successfully included inside the ceramics. Methyl orange (MO), Congo red (CR), and methylene blue (MB) were used to assess the composites’ ability to remove dyes. Catalytic hydrogenation, powered by in situ hydrogen production from NaBH₄ hydrolysis, demonstrated high removal efficiencies of 91–97% after 60 min. Adsorption, on the other hand, was ineffective. Despite undergoing four consecutive cycles without performance degradation, the materials demonstrated remarkable recyclability. Cu-MOF@ceramic composites are effective, durable, and practically applicable for improved wastewater treatment. Full article

Pyrolysis of plastic from waste electrical and electronic equipment (WEEE) is a promising method for producing value-added chemicals. However, flame retardants in WEEE can cause halogen contamination in pyrolysis oil, reducing its value. This work aims to develop an innovative catalytic hydrodehalogenation (CHD) protocol for the removal of chlorobenzene and bromobenzene. Iron sulphate heptahydrate (FeSO₄·7H₂O) and nickel ammonium sulphate hexahydrate ((NH₄)₂Ni(SO₄)₂·6H₂O) were used as catalysts, while sodium borohydride (NaBH₄) acted as a hydrogen donor for iron reduction. The novelty of the process lies in the generation of nano zero-valent iron (nZVI) that takes place within the CHD reactor (in situ) without the addition of strong acids. Various experimental set-ups were investigated to optimise the key process parameters (e.g., reagent concentrations). The optimal conditions—obtained in the autoclave at 30 °C with a 1:1 molar ratio of chlorobenzene to catalyst, omission of nickel salt, and 5 mmol of NaBH₄—resulted in a 75% reduction in chlorobenzene and complete removal of bromobenzene. The results confirm the effectiveness of the proposed protocol for the dehalogenation of chlorobenzene and bromobenzene, which can facilitate the valorization of pyrolysis oils derived from plastic waste, contributing to the closure of the WEEE cycle (the widest and fastest-growing source of global waste with significant environmental, social and economic impacts). Full article

The renewed interest in hydrogen peroxide-based space propulsion systems has highlighted the persistent issue of catalyst degradation during long-term operation. Although several studies have investigated the underlying causes of this phenomenon, effective regeneration techniques capable of restoring catalytic activity have not yet been clearly demonstrated. This study investigates the mechanisms responsible for performance degradation and proposes a viable regeneration strategy for palladium-based catalysts. Experimental analyses were conducted on a batch of commercial Al₂O₃/Pd pellets subjected to multiple firing cycles in a 10 N-class hybrid mini-thruster. Monitoring of the propulsive performance revealed a progressive decline in catalytic activity, ultimately preventing ignition of the hybrid rocket engine. To characterize the degradation mechanisms, the pellets were examined through visual inspection, static hydrogen peroxide decomposition tests, and Temperature Programmed Reduction (TPR) analysis. The results indicated significant surface oxidation of palladium, leading to reduced decomposition efficiency. A chemical regeneration procedure based on sodium borohydride (NaBH₄) treatment was subsequently developed to restore catalytic performance. The regenerated pellets were tested under the same experimental conditions that had previously led to ignition failure. Their propulsive performance was then compared with both the degraded pellets and a new batch of equivalent catalysts. The results demonstrate that the regeneration process successfully restored the catalytic activity to levels comparable with the original state, enabling stable and efficient hybrid combustion. These findings confirm the role of surface oxidation in catalyst degradation and demonstrate that targeted chemical treatment can significantly extend catalyst lifetime. The proposed regeneration strategy offers a practical method to reduce costs of ground-based experimental campaigns and support the future deployment of hydrogen peroxide-based propulsion systems in space applications by providing insights into the mechanisms that can degrade the performance of palladium catalysts. Full article

A systematic study of the chemoselectivity of the reduction of 3-methylcyclohex-2-enone (seudenone) to 3-methylcyclohex-2-enol (seudenol) was performed. Two approaches were investigated, namely the reduction of this ketone using NaBH₄ with modifiers and Catalytic Transfer Hydrogenation (CTH). The former resulted in higher conversions (95–99%) and high selectivity (up to 95%), whereas with CTH, a selectivity of 100% was achieved, albeit with a low conversion. The study therefore demonstrated that it is possible to chemoselectively reduce an α,β-unsaturated ketone in the liquid phase CTH using MgO as the catalyst and 2-pentanol as the hydrogen donor. The application of modifiers such as CeCl₃ · 7H₂O and MCl₂, where M = Be, Mg, Ca, Sr, and Ba, resulted in a significant improvement of the chemoselectivity (up to 95%) of the reduction with NaBH₄. The effect of parameters such as the solvent mixture composition, reaction temperature and modifier:NaBH₄ molar ratio was also investigated. In CTH, although high conversions of the ketone were observed for Al₂O₃, ZrO₂ and MgO in the vapor phase, the first two did not yield 3-methylcyclohex-2-enol among the obtained products. It was shown that 3-methylcyclohex-3-enol was the main product of the transformations of 3-methylcyclohex-2-enone in the presence of MgO, with yields of 25–33%. In a series of experiments, it was shown that 3-methylcyclohex-3-enol is formed as a result of the transformation of 3-methylcyclohex-2-enol in the presence of MgO as a catalyst. Full article

The generation of high-purity hydrogen via chemical reaction from hydrogen-rich materials is one of the ways in the alternative energy industry. In this approach, the utilization of catalytic materials that possess the capacity to initiate the decomposition of the starting material and the subsequent release of hydrogen is of paramount importance. In this study, nickel/cobalt-plated copper catalysts (NiCo/Cu) are presented, comprising from 4 to 90 wt.% of cobalt as catalytic materials for hydrogen generation via sodium borohydride (NaBH₄) hydrolysis reaction. The NiCo/Cu catalysts were synthesized via electroless deposition from glycine-based baths, utilizing Ni²⁺ and Co²⁺ ions as metal sources and morpholine borane (MB) as the reducing compound. The catalytic performance in alkaline NaBH₄ hydrolysis was found to correlate with the cobalt loading in the coating. The maximum rate of hydrogen production, which was determined to be 14.22 L min⁻¹ gcat⁻¹, was achieved at 343 K for a catalyst composed of 90 wt.% Co. The reaction proceeded with the activation energy of 52.5 kJ mol⁻¹, while the catalyst exhibited high durability, preserving nearly 88% of its initial activity after five successive reaction cycles. The combination of nickel and cobalt, along with their synergistic effect and high efficiency in the borohydride hydrolysis reaction, makes them promising catalysts. Full article

This study focuses on the synthesis and characterization of buckwheat husk-derived activated carbon, chemically activated with potassium hydroxide (KOH) and subsequently modified with urea and Prussian Blue (PB). The obtained carbons were evaluated in terms of particle-size distribution, surface morphology, structural features, and electrokinetic properties using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and electrophoresis, as well as N₂ adsorption–desorption (BET surface area and porosity analysis). The results confirmed that both pyrolysis conditions and the type of modifier significantly affect the physicochemical properties of the activated carbon and its behavior in electrolyte solutions. Colloidal stability and particle size were strongly dependent on pH and the type of anions present in solution, with sodium nitrate (NaNO₃) systems showing higher stability than sodium chloride (NaCl). Modification with KOH and urea imparted a more basic surface character, whereas PB introduced more acidic properties. All samples exhibited predominantly negative surface charges and mesoporous structures, which are favorable for adsorption processes and enhance affinity for heavy-metal cations. Among the tested materials, BH-KOH-Fe (Fe-modified KOH-activated carbon) showed the most favorable performance for the targeted application, while BH-KOH (KOH-activated buckwheat husk-derived carbon) exhibited high surface area and good colloidal stability. The prepared materials show promising applicability for water purification, including the removal of organic pollutants and radionuclides (e.g., ¹³⁷Cs and ⁹⁰Sr), as well as metal cations (K⁺, Na⁺, and Li⁺). Full article

Biosurfactants produced by halophilic bacteria are gaining attention as eco-friendly and biocompatible alternatives to synthetic surfactants due to their high surface activity, stability under extreme conditions, and intrinsic antimicrobial properties. These amphiphilic biomolecules hold great promise for bioremediation, biomedical, and pharmaceutical applications. In this study, moderately halophilic bacteria capable of biosurfactant production were isolated from saline mud collected at the Burgas solar salterns (Bulgaria). The halophilic microbiota was enriched in Bushnell–Haas (BH) medium containing 10% NaCl amended with different carbon sources. Primary screening in BH liquid medium evaluated the isolates’ ability to degrade n-hexadecane while at the same time producing biosurfactants. Thirty halophilic bacterial strains were isolated on BH agar plates supplemented with 2% n-hexadecane, 2% olive oil, or 2% glycerol. Four isolates—BS7OL, BS8OL, BS9GL, and BS10HD—with strong emulsifying activity (E₂₄ = 56%) and reduced surface tension in the range of 27.3–45 mN/m were derived after 7 days of batch fermentation. Strain BS10HD was chosen as the most potent biosurfactant producer. Its phylogenetic affiliation was determined by 16S rRNA gene sequence analysis; according to the nucleotide sequence, it was assigned to Halomonas ventosae. The extract material was analysed by thin-layer chromatography (TLC) and Fourier transform infrared spectroscopy (FTIR). Upon spraying the TLC plate with ninhydrin reagent, the appearance of a pink spot indicated the presence of amine functional groups. FTIR analysis showed characteristic peaks for both lipid and peptide functional groups. Based on the observed physicochemical properties and analytical data, it can be suggested that the biosurfactant produced by Halomonas ventosae BS10HD is a lipopeptide compound. Full article

Groundwater is the main water source for irrigated agriculture, accounting for an increasing share of the domestic supply in the hyper-arid district of La Yarada Los Palos (Tacna, Peru); however, at the sector scale, concerns about arsenic, boron and salinity remain poorly quantified. Arsenic and boron were selected as target contaminants because of their naturally elevated concentrations associated with coastal and volcanic hydrogeological settings, and their well-documented implications for human health and irrigation suitability. This study reports a 12-month monitoring program (September 2024–August 2025) in three irrigated sectors, in which wells were sampled monthly and analyzed by inductively coupled plasma–mass spectrometry (ICP-MS) for total arsenic, boron, lithium and sodium, along with electrical conductivity, pH, temperature and total dissolved solids. The sector–month total arsenic means ranged from 0.0089 to 0.0143 mg L⁻¹, with 33 of 36 exceeding the 0.010 mg L⁻¹ drinking water benchmark recommended by the World Health Organization (WHO). Total boron ranged from 1.11 to 2.76 mg L⁻¹, meaning that all observations were above the 0.5 mg L⁻¹ irrigation guideline for agricultural use proposed by the United Nations Food and Agriculture Organization (FAO). A marked salinity gradient was observed from the inland Sector 1-BH (median Na ≈ 77 mg L⁻¹; EC ≈ 1.2 mS cm⁻¹) to the coastal Sector 3-LC (median Na ≈ 251 mg L⁻¹; EC ≈ 3.3 mS cm⁻¹), with Sector 2-FS showing intermediate salinity but the highest median boron and lithium levels. Spearman rank correlations indicate that sodium, electrical conductivity and total dissolved solids define the main salinity axis, whereas arsenic is only moderately associated with boron and lithium and is not a simple function of bulk salinity. Taken together, these results show that groundwater from the monitored wells is not safe for drinking without treatment and is subject to at least moderate boron-related irrigation restrictions. The sector-resolved dataset provides a quantitative baseline for La Yarada Los Palos and a foundation for future work integrating expanded monitoring, health-risk metrics and management scenarios for arsenic, boron and salinity in hyper-arid coastal aquifers. Full article

Hexahydrocannabinol (HHC), a hydrogenated derivative of Δ⁹-tetrahydrocannabinol (Δ⁹-THC), is a semi-synthetic cannabinoid marketed as an alternative to Δ⁹-THC. Its hydroxylated metabolite, 8-hydroxyhexahydrocannabinol (8-OH-HHC), exists as four stereoisomers: (6aR,8R,9R,10aR), (6aR,8S,9S,10aR), (6aR,8S,9R,10aR), and (6aR,8R,9S,10aR). However, the lack of reference standards has hindered pharmacokinetic and forensic studies. This work reports the first stereoselective synthesis and structural confirmation of all four 8-OH-HHC stereoisomers. Two strategies were employed: hydroboration–oxidation and epoxidation–reduction. Hydroboration of Δ⁸-THC with BH₃·THF followed by oxidation predominantly produced anti-isomers (6aR,8R,9R,10aR) and (6aR,8S,9S,10aR) in moderate yields, along with small amounts of syn-isomer (6aR,8S,9R,10aR), suggesting an atypical mechanistic pathway. In contrast, syn-isomers (6aR,8S,9R,10aR) and (6aR,8R,9S,10aR) were accessed via epoxidation of Δ⁸-THC acetate using mCPBA and subsequent reduction with NaBH₃CN/BF₃·OEt₂, affording the desired products with moderate selectivity. Absolute configurations were confirmed by nuclear Overhauser effect spectroscopy (NOESY). These methods will facilitate future pharmacokinetic and forensic research and support the development of improved detection strategies. Full article

To address gaps in the characterization of Roman chamomile (Anthemis nobilis L., Asteraceae)—an ethnobotanically and commercially important species—we profiled its essential oil (EO), focusing on esters that are incompletely characterized or unreported. Comprehensive GC-MS of two commercial EOs and their chromatographic fractions, combined with synthesis and co-injection of reference compounds, enabled the identification of 190 constituents. We uncovered a homologous series of angelates, tiglates, and senecioates by partial-ion-current (PIC) screening (m/z 55, 83, 100, 101), augmented by co-injection and NMR confirmation. Among these EO constituents, four esters, methallyl 3-methylbutanoate (6h), methallyl senecioate (3h), 3-methylpentyl 2-methylbutanoate (5c), and 5-methylhexyl angelate (2g) are reported here as new natural products and previously unreported compounds in the literature. Selected methacrylates and related α,β-unsaturated esters underwent model Michael additions to methanethiol (generated in situ from dimethyl disulfide and NaBH₄), confirming their thiol-acceptor reactivity. In an Artemia salina assay, the EO and most esters were non-toxic; methacrylates showed only low toxicity at the highest concentrations. These results refine the chemical map of A. nobilis EO and highlight specific ester families for future mechanistic and biological evaluation. Full article

Glyphosate (GLY) is a systemic herbicide used in agriculture and has a carcinogenic effect after long-term usage. Herein, a molecularly imprinted electrochemical sensor based on palladium@yttrium oxide@boron nitride nanosheets (Pd/Y₂O₃@BN) nanocomposite was developed for the detection of GLY in drinking water. After the preparation of Pd/Y₂O₃@BN nanocomposite by using sonication and NaBH₄ reduction methods, Pd/Y₂O₃@BN nanocomposite as electrode material was applied on glassy carbon electrode by infrared lamp. Then, a molecularly imprinted glassy carbon electrode based on Pd/Y₂O₃@BN (MIP) was designed with cyclic voltammetry (CV) in presence of pyrrole monomer and GLY molecule. After the spectroscopic and microscopic characterizations, the linearity in the range of 1.0 × 10⁻⁹–1.0 × 10⁻⁸ M with a detection limit (LOD) of 3.3 × 10⁻¹⁰ M was obtained for GLY molecule. After MIP electrode was applied to drinking water samples with high recovery, the selectivity, stability, repeatability, and reproducibility features were studied. These promising results suggested that the as-fabricated MIP electrode presented a novel and highly effective approach for GLY assay. Full article

Divalent europium complexes have attracted significant attention in various fields due to the unique electronic configuration of the Eu(II) ion. Given the high sensitivity of the 5d → 4f emission of Eu(II) ions to the ligand field, it is crucial to explore the relationship between ligands and this emission in Eu(II) complexes. However, the heavy-atom effects on the 5d → 4f emission of Eu(II) complexes coordinated with non-metal elements in the same group remain unclear. In this study, five mononuclear Eu(II)-chalcogenide complexes, Eu[H₃B·EPh-κE,H,H]₂(DME)₂ (E = S for 1 and Se for 2; DME = 1,2-Dimethoxyethane) and Eu[EPh]₂(18-C-6) (E = S for 3, Se for 4, and Te for 5; 18-C-6 = 1,4,7,10,13,16-Hexaoxacyclooctadecane), were synthesized via reduction of diphenyl disulfide chalcogenide analogs with Eu(BH₄)₂(THF)₂ or NaH. The structures of these complexes were investigated by single-crystal X-ray diffraction, and their properties were characterized by thermogravimetric analysis and photophysical property tests. Complexes 1 and 2 are isomorphous and show similar yellowish-green luminescence, while complexes 3–5 have similar structures but crystallize in different space groups with bluish-green luminescence. This research reveals the influence of chalcogenide ligands on the 5d → 4f emission of Eu(II) complexes, providing a theoretical basis and new research ideas for the application of Eu(II) complexes in various fields, including luminescent materials, cryogenic refrigerants, and magnetic materials. Full article