Search Results (172)

The treatment of contaminants from road infrastructure poses significant challenges due to their variable composition and the high concentrations of chloride ions, heavy metals, and oil-derived substances. Traditional methods for protecting groundwater environments are often insufficient. A promising alternative is permeable reactive barrier (PRB) technology, which utilizes recycled materials and construction waste as reactive components within the treatment zone of the ground. This paper delves into the potential of employing a composite (MIX) consisting of modified construction aggregate (as recycled material) and activated carbon (example of reactive material) to address environmental contamination from a mixture of heavy metals and chloride. The research involved chemical modifications of the road aggregate, activated carbon, and their composite, followed by laboratory tests in glass reactors and non-flow batch tests to evaluate the kinetics and chemical equilibrium of the reactions. The adsorption process was stable and conformed to the pseudo-second-order kinetics and Langmuir, Toth, and Redlich–Peterson isotherm models. Studies using MIX from a heavy metal model solution showed that monolayer adsorption was a key mechanism for removing heavy metals, with strong fits to the Langmuir (R² > 0.80) and Freundlich models, and optimal efficiencies for Cd and Ni (R² > 0.90). The best fit, at Cd, Cu, Ni = 0.96, however, was with the Redlich–Peterson isotherm, indicating a mix of physical and chemical adsorption on heterogeneous surfaces. The Toth model was significant for all analytes, fitting Cl and Cd well and Pb and Zn moderately. The modifications made to the composite significantly enhanced its effectiveness in removing the contaminant mixture. The test results demonstrated an average reduction of chloride by 85%, along with substantial removals of heavy metals: lead (Pb) by 90%, cadmium (Cd) by 86%, nickel (Ni) by 85%, copper (Cu) by 81%, and zinc (Zn) by 79%. Further research should focus on the removal of other contaminants and the optimization of magnesium oxide (MgO) dosage. Full article

Thin films of manganese–nickel–cobalt oxide with graphene (G@MNCO) were deposited on copper foam using electrochemical deposition. NiCo₂O₄ is the main phase in these films. As the proportion of graphene in the precursor solution increases, the oxygen vacancies in the samples also increase. The microstructure of these samples evolves into hierarchical vertical flake structures. Cyclic voltammetry measurements conducted within the potential range of 0–1.2 V reveal that the electrode with the highest graphene content achieves the highest specific capacitance, approximately 475 F/g. Furthermore, it exhibits excellent cycling durability, maintaining 95.0% of its initial capacitance after 10,000 cycles. The superior electrochemical performance of the graphene-enhanced, manganese-doped nickel–cobalt oxide electrode is attributed to the synergistic contributions of the hierarchical G@MNCO structure, the three-dimensional Cu foam current collector, and the binder-free fabrication process. These features promote quicker electrolyte ion diffusion into the electrode material and ensure robust adhesion of the active materials to the current collector. Full article

In this work, Guar gum and copper oxide-nickel oxide (GG-CuO-NiO) hydrogel were produced with the help of formaldehyde solution to display an efficient catalytic performance toward the catalytic degradation of selected dyes (Methylene Blue (MB), Methyl Orange (MO), and Eosin Yellow (EY)) in the presence of NaBH₄. The morphological and structural properties of the prepared hydrogel were thoroughly analyzed using SEM, EDX, XRD, and FT-IR techniques. According to the results, the GG-CuO-NiO hydrogel was able to reduce MB by 95% in one minute, 90.0% in four minutes, and 80.0% in 10 min for MO and EY, respectively. The catalytic efficiency of the hydrogel for MB was studied by adjusting its concentrations, varying reducing agent concentrations, and altering the amount of gel used. Using the recyclability method, which involved testing the GG-CuO-NiO hydrogel multiple times for the reduction of MB, the stability, reusability, and loss of catalytic activity of the hydrogel were examined. As a result, the designed GG-CuO-NiO hydrogel was stable for up to four times toward the reduction of MB. Lastly, the efficiency of the GG-CuO-NiO hydrogel was evaluated for MB removal in real samples and displayed exceptional reduction capabilities. Full article

Bimetals—materials composed of two metal components with dissimilar standard reduction–oxidation (redox) potentials—offer unique electronic, optical, and catalytic properties, surpassing monometallic systems. These materials exhibit not only the combined attributes of their constituent metals but also new and novel properties arising from their synergy. Although many reviews have explored the synthesis, properties, and applications of bimetallic systems, none have focused exclusively on iron (Fe)- and aluminum (Al)-based bimetals. This systematic review addresses this gap by providing a comprehensive overview of conventional and emerging techniques for Fe-based and Al-based bimetal synthesis. Specifically, this work systematically reviewed recent studies from 2014 to 2023 using the Scopus, Web of Science (WoS), and Google Scholar databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and was registered under INPLASY with the registration number INPLASY202540026. Articles were excluded if they were inaccessible, non-English, review articles, conference papers, book chapters, or not directly related to the synthesis of Fe- or Al-based bimetals. Additionally, a bibliometric analysis was performed to evaluate the research trends on the synthesis of Fe-based and Al-based bimetals. Based on the 122 articles analyzed, Fe-based and Al-based bimetal synthesis methods were classified into three types: (i) physical, (ii) chemical, and (iii) biological techniques. Physical methods include mechanical alloying, radiolysis, sonochemical methods, the electrical explosion of metal wires, and magnetic field-assisted laser ablation in liquid (MF-LAL). In comparison, chemical protocols covered reduction, dealloying, supported particle methods, thermogravimetric methods, seed-mediated growth, galvanic replacement, and electrochemical synthesis. Meanwhile, biological techniques utilized plant extracts, chitosan, alginate, and cellulose-based materials as reducing agents and stabilizers during bimetal synthesis. Research works on the synthesis of Fe-based and Al-based bimetals initially declined but increased in 2018, followed by a stable trend, with 50% of the total studies conducted in the last five years. China led in the number of publications (62.3%), followed by Russia, Australia, and India, while Saudi Arabia had the highest number of citations per document (95). RSC Advances was the most active journal, publishing eight papers from 2014 to 2023, while Applied Catalysis B: Environmental had the highest number of citations per document at 203. Among the three synthesis methods, chemical techniques dominated, particularly supported particles, galvanic replacement, and chemical reduction, while biological and physical methods have started gaining interest. Iron–copper (Fe/Cu), iron–aluminum (Fe/Al), and iron–nickel (Fe/Ni) were the most commonly synthesized bimetals in the last 10 years. Finally, this work was funded by DOST-PCIEERD and DOST-ERDT. Full article

Single-junction perovskite solar cells (PSCs) have been one of the most promising photovoltaic technologies owing to their high-power conversion efficiencies (PCEs) of ~27% and the low-cost fabrication processes involved, which pay off significantly given their distinct structural characteristics. Recently, inorganic hole-transport materials (HTMs) such as nickel oxide (NiO_x) have been developed and received considerable attention for use in OPVs due to their excellent thermal stability, low-cost materials, and compatibility with scalable deposition methods. Here, we summarize the recent progress on inorganic HTMs for PSCs, which can be divided into three categories: NiO_x, copper-based compounds, and emerging new alternatives. The deposition method (sputtering, atomic layer deposition, or a solution-based technique) is one of the most important factors affecting the performance and stability of PSCs. Finally, we review interfacial engineering strategies, such as surface modifications and doping, which can enhance charge transport and extend a device’s lifetime. We also balance the benefits of inorganic HTMs against the key challenges in advancing to commercialization, namely interior defects and environmental degradation. In this review, we summarize the recent progress and challenges toward developing cost-efficient and stable PSCs with inorganic HTMs and provide insights into the future development of these materials. Full article

Nanotechnology is emerging as an innovative and sustainable agricultural approach that minimizes environmental impacts by developing nanostructured materials to promote plant growth and combat plant-parasitic nematodes (PPNs). Plant-based nanoparticles (NPs) are attracting increasing attention as they are more environmentally friendly, economical and biocompatible compared to traditional chemical and physical synthesis methods. The ability of plants to reduce and stabilize metal ions and form NPs of specific size and morphology through their biochemical content offers great advantages for agricultural applications. Phytochemicals produced by plants enable the biological synthesis of metal and metal oxide NPs by acting as reducing agents and coating agents in NP synthesis. The effects of plant-based NPs in nematode control are based on mechanisms such as the disruption of the nematode cuticle, induction of oxidative stress and interference with parasite metabolism. Several plant species have been investigated for the synthesis of metal and metal oxide nanoparticles such as silver (Ag-NPs), nickel oxide (NiO-NPs), zinc oxide (ZnO-NPs), copper oxide (CuO-NPs) and iron (Fe-NPs). These biologically synthesized NPs show potent biological activity against important PPNs such as Meloidogyne spp., Pratylenchus spp. and Heterodera spp. The integration of plant-derived NPs into agricultural systems has significant potential for plant growth promotion, nematode suppression and soil health improvement. This review highlights their role in reducing environmental impact in agricultural applications by examining the sustainable synthesis processes of plant-based NPs. Full article

The historical industrial waste deposit Gater was used to dispose of different metallurgy wastes from lead and zinc production. The metallurgical waste deposit was situated in the open space, between the tailing waste deposit Žitkovac and river Ibar flow. Large amounts of lead-containing wastes are produced in the non-ferrous metallurgical industry, such as lead ash and lead slag generated in Pb smelting, lead anode slime, and lead sludge produced in the raw lead refining process. In addition to the lead concentration, numerous valuable components are found in the lead refinery waste from the group of Critical Raw Materials, such as antimony, arsenic, bismuth, copper, nickel, magnesium, scandium, as well as Rare-Earth Elements. Samples with eight characteristic points were taken to obtain relevant data indicating a possible recycling method. The chemical composition analysis was conducted using ICP; the scanning was completed using SEM-EDS. The mineralogical composition was determined by using XRD. The chemical analysis showed a wide range of valuable metal concentrations, from Ag (in the range from 14.2 to 214.6, with an average 86.25 mg/kg) to heavy metals such as Cu (in the range from 282.7 to 28,298, with an average 10,683.7 mg/kg or 1.0683% that corresponds to some active mines), Ni and Zn (in the range from 1.259 to 69,853.4, with an average 14,304.81 mg/kg), Sc (in the range from 2.4 to 75.3, with an average 33.61 mg/kg), Pb (in the range from 862.6 to 154,027.5, with an average 45,046 mg/kg), Sb (in the range from 51.7 to 18,514.7, with an average 2267.8 mg/kg), Ca (in the range from 167.5 to 63,963, with an average 19,880 mg/kg), Mg (in the range from 668.3 to 76,824.5, with an average 31,670 mg/kg), and As (in the range from 62.9 to 24,328.1, with an average 5829.53 mg/kg). The mineralogy analysis shows that all metals are in the form of oxides, but in the case of As and Fe, SEM-EDS shows some portion of elemental lead, pyrite, and silica-magnesium-calcium oxides as slag and tailing waste residues. The proposed recovery process should start with leaching, and further investigation should decide on the type of leaching procedure and agents, considering the waste’s heterogeneous nature and acidity and toxicity. Full article

In this study, the selective separation of copper ions (Cu²⁺) from leaching solutions containing both Cu²⁺ and nickel ions (Ni²⁺) was investigated using electrolysis cells with high convection (Chemelec). Firstly, the electrochemical behavior of solutions containing only single Cu²⁺, single Ni²⁺, and both Cu²⁺ and Ni²⁺ was investigated using cyclic voltammetry (CV). Cu²⁺ reduction was observed at −0.15 V in solutions that contained either simply Cu²⁺ or a Cu²⁺-Ni²⁺ combination, whereas oxidation happened at 0.17 V in a single step. The CV analysis of a Ni²⁺-containing solution at pH 1 revealed that Ni²⁺ was not reduced. Potentiostatic selective Cu²⁺ reduction experiments were conducted at cathode potentials of −0.3 V, −0.4 V, and −0.5 V. Increasing the potential from −0.3 V to −0.5 V enhanced copper recovery from 84% to 94%. The current efficiency remained above 90% across all three potentials during 3 h experiments. At −0.5 V, extending the experiment time from 3 h to 5 h resulted in copper recovery exceeding 99%, while current efficiency declined from 90% to 80%. The cathode products were analyzed using X-ray diffraction (XRD), revealing that the main phase consisted of metallic copper. Full article

This study employed an in-situ displacement technique to eliminate the oxide layer present on the surface of micron aluminum (μAl). Utilizing the exposed metallic aluminum, we facilitated the displacement of copper and nickel nanoparticles. These nanoparticles, approximately 90 nanometers in size, were densely adhered to the surface of the μAl particles. The elemental composition and structural characteristics of the composite particles were meticulously analyzed using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS), Vibrating Sample Magnetometry (VSM), and X-Ray Photoelectron Spectroscopy (XPS). Subsequently, thermal analysis and combustion performance assessments were conducted to elucidate the catalytic effects of the composite particles ([nCu+nNi]/μAl) on the thermal decomposition and combustion efficiency of ammonium perchlorate (AP). The results elucidate that the nanoparticles immobilized on the surface of μAl are unequivocally metallic copper (nCu) and metallic nickel (nNi). Following the application of nCu and nNi, the oxidation reaction of μAl accelerated by nearly 400 °C; furthermore, the incorporation of [nCu+nNi]/μAl raised the thermal decomposition peak temperature of AP by approximately 130 °C. Notably, the thermal decomposition activation energy of raw AP reached as high as 241.7 kJ/mol; however, upon doping with [nCu+nNi]/μAl, this activation energy significantly diminished to 161.4 kJ/mol. The findings of the combustion experiments revealed that both the raw AP and the AP modified solely with μAl were impervious to ignition via the hot wire method. In contrast, the AP doped with [nCu+nNi]/μAl demonstrated pronounced combustion characteristics, achieving an impressive peak flame temperature of 1851 °C. These results substantiate that the nCu and nNi, when deposited on the surface of μAl, not only facilitate the oxidation and combustion of μAl but also significantly enhance the thermal decomposition and combustion dynamics of ammonium perchlorate. Consequently, the [nCu+nNi]/μAl composite shows considerable promise for application in high-burn-rate hydroxyl-terminated polybutadiene (HTPB) propellants. Full article

Here, we report the characterization of two Cupriavidus strains, NOV2-1 and OV2-1, isolated from an iron-oxide deposit in an underground tunnel of the Naica mine in Mexico. This unique biotope, characterized by its high temperature (≈50 °C) and the presence of heavy metals, is no longer available for sampling at this time. The genomes of NOV2-1 and OV2-1 comprised two replicons: a chromosome of 3.58 and 3.53 Mb, respectively, and a chromid of 2.1 Mb in both strains. No plasmids were found. The average nucleotide identity and the core genome phylogeny showed that NOV2-1 and OV2-1 belonged to the Cupriavidus gilardii species. NOV2-1 and OV2-1 grew up to 48 °C, with an optimal temperature of 42 °C. Discrete differences were observed between C. gilardii CCUG38401^T, NOV2-1, and OV2-1 in the biochemical tests. NOV2-1 and OV2-1 presented resistance to zinc, lead, copper, cadmium, nickel, and cobalt. Several complete and incomplete gene clusters related to the resistance to these heavy metals (ars, czc, cop 1, sil-cop 2, cup, mmf, and mer) were detected in the genome of these strains. Although further studies are needed to determine the origin and role of the detected gene clusters, it is suggested that the czc system may have been mobilized by horizontal gene transfer. This study expands the extreme biotopes where Cupriavidus strains can be retrieved. Full article

This paper presents a non-enzymatic sensor for glucose detection in an environment where glucose and insulin coexist. The sensor is based on a three-electrode chip fabricated by etching the copper foil of a printed circuit board. The working electrode is coated with a graphene oxide-polyvinyl alcohol composite film, followed by the electroplating of a nickel–cobalt layer and an additional surface treatment using O₂ plasma. The experimental results indicate that within a glucose concentration of 2 mM to 10 mM and an insulin concentration of 0.1 mM to 1 mM, the measured current exhibits a linear relationship with the concentration of glucose or insulin, regardless of whether cyclic voltammetry or linear sweep voltammetry is used. However, the detection limit for insulin is 0.01 mM, ensuring that glucose detection remains unaffected by insulin interference. In this sensor, nickel–cobalt serves as a catalyst for glucose and insulin detection, while the graphene oxide-polyvinyl alcohol composite enhances sensing performance. Full article

The advancement in catalytic processes utilizing sustainable raw materials, such as bioethanol, represents a key scientific challenge in this century. One potential approach to producing 1-butanol, a compound primarily obtained from petroleum-derived sources, is through the Guerbet reaction. For this transformation, various multifunctional catalysts have been explored, some of which incorporate Cu and/or Ni nanoparticles that facilitate hydrogenation and dehydrogenation reactions, along with magnesium oxide, which provides the necessary acid/base functionality. To promote nanoparticle formation and maximize the exposed active surface area, high-surface-area graphite (HSAG), a hydrophobic and inert support material, emerges as a promising candidate. In this study, different catalyst formulations containing these components were tested under moderate reaction conditions, at temperatures between 440 and 580 K and a pressure of 50 bar. A strong correlation was observed between butanol selectivity and the presence of medium–high strength basic sites, complemented by moderate acidity. Furthermore, optimizing the copper and nickel loadings to 4 wt.% Cu and 1 wt.% Ni significantly minimized the formation of unwanted byproducts. The highest butanol selectivity (44%) was achieved using a 4Cu1Ni-Mg/HSAG catalyst, which had been pretreated in helium at 723 K before H₂ reduction, yielding approximately 9% 1-butanol. Full article

The development of micro glucose sensors plays a vital role in the management and monitoring of diabetes, facilitating real-time tracking of blood glucose levels. In this paper, we developed a three-layer core-sheath microwire (NW@CuO@Co₃O₄) with nickel wire as the core and copper oxide and cobalt oxide nanowires as the sheath. The unique core-sheath structure of microwire enables it to have both good conductivity and excellent electrochemical catalytic activity when used as an electrode for glucose detecting. The non-enzymatic glucose sensor base on a NW@CuO@Co₃O₄ core-sheath wire exhibits a high sensitivity of 4053.1 μA mM⁻¹ cm⁻², a low detection limit 0.89 μM, and a short response time of less than 2 s. Full article

Background: Associations of antioxidants in prenatal over-the-counter multivitamin-mineral (OTC MVM) supplements with in-utero oxidative stress (OS), antioxidant capacity, and fetal growth are limited. Our objectives were to determine if five fetal ultrasound measurements [biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), and estimated fetal weight] were associated with OTC MVM supplements and with minerals, biomarkers of OS, and total antioxidant capacity in amniotic fluid (AF). Methods: For this retrospective study, 176 pregnant women who had undergone age-related amniocentesis for genetic testing were included. Questionnaires recorded prenatal OTC MVM supplementation (yes, no). Ultrasound measurements for early (16–20 weeks) and late (32–36 weeks) gestation were extracted from medical charts. AF concentrations for 15 minerals and trace elements and OS biomarkers in AF [nitric oxide (NO), thiobarbituric acid-reactive substances (TBARS), and ferric-reducing antioxidant power (FRAP)] were measured at 12–20 weeks of gestation. Associations of AF minerals, OS biomarkers, and ultrasound measures were analyzed using multiple linear regressions. Results: Positive associations were observed between AF TBARS and seven AF minerals/elements (calcium, copper, magnesium, nickel, strontium, zinc and iron). At 16–20 weeks, AF copper, nickel, strontium, and selenium were positively associated with BPD, HC, AC, and FL, respectively, NO was positively associated with FL, and FRAP was inversely associated with estimated weight. At 32–36 weeks, calcium was positively associated with BPD and chromium and arsenic were negatively with HC. At 16–20 weeks, higher AF FRAP was inversely associated with FL and this exposure continued to be inversely associated with estimated weight at 32–36 weeks. Conclusions: Concentrations of AF minerals, trace elements and biomarkers of OS and in-utero antioxidant capacity were linked to specific ultrasound measurements at different stages of gestation, suggesting a complex interplay among in utero OS, antioxidant capacity, OTC MVM supplements, and fetal growth. Full article

Heavy metals (HMs) exert a negative impact on physiological processes in plants, which can adversely affect the productivity of agricultural crops. In this experiment, we assessed the potential to mitigate the toxic effects of HMs on soft wheat through the use of rhizospheric microorganisms from the genus Azospirillum. In the initial phase of the experiment, we identified the most resistant Azospirillum strains to Cu (from 1.5 to 15 mg/L), Ni (from 2 to 20 mg/L), and Pb (from 15.9 to 159.4 mg/L). Both Ni and Pb significantly inhibited bacterial growth and induced substantial oxidative stress in the majority of the studied strains. The strain A. picis B-2897^T exhibited the highest resistance to all HMs. The cultivation of wheat in soil supplemented with Cu led to an increased growth rate and enhanced wheat productivity. Conversely, Ni and Pb reduced wheat productivity by 65% and 27%, respectively. This was accompanied by chlorophyll depletion and a decrease in the expression of genes NDOR and GST, which are involved in xenobiotic detoxification. Pre-inoculation of seeds with Azospirillum led to a decrease in HM concentration in the plant seedlings; in particular, A. picis B-2897^T reduced the level of Ni from 0.005% to a concentration below the detectable level (i.e., below 0.001%), and Pb from 0.014% to 0.008%. The bacteria stimulated the expression of genes responsible for xenobiotic detoxification and contributed to the increased growth and productivity of wheat. Thus, Azospirillum can be utilized as a bioproduct to alleviate the toxic effects of HMs. Full article