Search Results (52)

This paper presents the results of a study on the development of a processing technology for pyrite–cobalt concentrates to obtain iron oxide pigments (Fe₂O₃ and Fe₃O₄) via high-temperature hydrolysis. It was found that, in a single operation, the concentrate can be effectively purified from lead, zinc, and copper, yielding an iron–nickel–cobalt product suitable for further processing by standard technologies, such as smelting into ferronickel. The scientific originality of research concludes in a mechanism of stepwise selective chloride volatilization, which was established as follows: stage I (500–650 °C)—removal of lead; stage II (700–750 °C)—chlorination of copper and iron; stage III (850–900 °C)—volatilization of nickel and cobalt. Microprobe analysis of the powders obtained from high-temperature hydrolysis of FeCl₂·4H₂O and FeCl₃·6H₂O revealed the resulting Fe₃O₄ and Fe₂O₃ powders with particle sizes 50 μm and 100 μm. A visual color palette was created, corresponding to different Fe₃O₄/Fe₂O₃ ratios in the pigment composition—ranging from black (magnetite) to red (hematite)—and potential application areas. For the first time, the new technological scheme was proposed of pigments Fe₂O₃ and Fe₃O₄ production from pyrite–cobalt concentrates via combination of oxidized roasting with subsequent chlorination and high-temperature hydrolysis of the products. Full article

Porphyrins play an extremely important role in both photodynamic (PDT) and sonodynamic therapy (SDT). These techniques, which have a lot in common, are largely based on the interaction between the sensitizer and light or ultrasounds (US), respectively, resulting in the formation of reactive oxygen species (ROS) that have the ability to destroy target cells. SDT requires the use of an appropriate frequency of US waves that are able to excite the chemical compound used. In this study, five porphyrin complexes were used: free-base meso-tetra(N-methyl-pyridinium-4-yl)porphyrin (TMPyP) and its transition metal complexes containing zinc(II), palladium(II), copper(II), and chloride-iron(II). The sonodynamic activity of these compounds was studied in vitro. The obtained results confirm the significant relationship between the chemical structure of the macrocycle and its stability and ability to generate ROS. The highest efficiency in ROS generation and high stability were demonstrated by non-metalated compound and its complex with zinc(II), while complex with copper(II), although less stable, were equally effective in terms of ROS production. Antibacterial activity tests showed the unique properties of the tested compounds, including a reduction in the number of both planktonic and biofilm antibiotic-resistant microorganisms above 5 log, which is rare among sonosensitizers. Full article

An aqueous leaf extract of Egeria densa was used to green-synthesize iron (II) and iron (III) oxide nanoparticles from ferrous sulphate and ferric chloride, respectively. The successful green synthesis of the nanoparticles was confirmed through UV–visible spectroscopy, and the colour of the mixtures changed from light-yellow to green-black and reddish-brown for FeO–NPs and Fe₂O₃–NPs, respectively. The morphological characteristics of the nanoparticles were determined using an X-ray diffractometer (XRD), a Fourier transform infrared spectrophotometer (FTIR), a transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDX). The UV–Vis spectrum of the FeO–NPs showed a sharp peak at 290 nm due to the surface plasmon resonance, while that of the Fe₂O₃–NPs showed a sharp peak at 300 nm. TEM analysis revealed that the FeO–NPs were oval to hexagonal in shape and were clustered together with an average size of 18.49 nm, while the Fe₂O₃-NPs were also oval to hexagonal in shape, but some were irregularly shaped, and they clustered together with an average size of 27.96 nm. EDX analysis showed the presence of elemental iron and oxygen in both types of nanoparticles, indicating that these nanoparticles were essentially present in oxide form. The XRD patterns of both the FeO–NPs and Fe₂O₃–NPs depicted that the nanoparticles produced were crystalline in nature and exhibited the rhombohedral crystal structure of hematite. The FT-IR spectra revealed that phenolic compounds were present on the surface of the nanoparticles and were responsible for reducing the iron salts into FeO–NPs and Fe₂O₃–NPs. Conclusively, this work demonstrated for the first time the ability of Elodea aqueous extract to synthesize iron-based nanoparticles from both iron (II) and iron (III) salts, highlighting its versatility as a green reducing and stabilizing agent. The dual-path synthesis approach provides new insights into the influence of the precursor oxidation state on nanoparticle formation, thereby expanding our understanding of plant-mediated nanoparticle production and offering a sustainable route for the fabrication of diverse iron oxide nanostructures. Furthermore, it provides a simple, cost-effective, and environmentally friendly method for the synthesis of the FeO–NPs and Fe₂O₃–NPs using Egeria densa. Full article

In the present work, meso-tetrakis(2,4,6-trimethylphenyl) porphyrinato)zinc(II): ([Zn(TMP)] (1), meso-tetrakis-(tetraphenyl)porphyrin iron(III))chloride): [Fe(TPP)Cl] (2), and meso-tetrakis(phenyl)porphyrin manganese(III) chloride): [Mn(TPP)Cl] (3) were synthesized. Then, the three prepared porphyrinic complexes (1–3) were functionalized with branched polyethyleneimine (PEI). The prepared complexes were thoroughly analyzed using several analytical techniques, including ¹H NMR, FT-IR, UV-vis, XRD, XRF, TGA-DTA, SEM, and EDX. The presence of sharp main peaks at 2θ between 10° and 80°, in XRD analysis, for all studied compounds suggested the crystalline nature of the porphyrinic complexes. The morphological properties of the porphyrininc complexes were significantly affected by the chemical modification with polyethyleneimine. EDX result confirmed the complexation of zinc, iron, and manganese metals with the porphyrinic core. The increase in carbon and nitrogen contents after the addition of polyethyleneimine to the complexes (1–3) was noticeable. After thermal decomposition, the total mass loss was equal to 92.97%, 66.77%, and 26.78% for complexes (1), (2), and (3), respectively. However, for the complex (1)-PEI, complex (2)-PEI, and complex (3)-PEI, the total mass losses were 83.12%, 81.88%, and 35.78%, respectively. The synthetic compounds were additionally utilized for the adsorption of Naphthol blue black B from water. At optimum adsorption conditions (T = 20 °C, time = 60 min, pH = 5), the highest adsorption capacities were 154 mg/g, 139 mg/g, and 119 mg/g for complex (3)-PEI, complex (2)-PEI, and complex (1)-PEI, respectively. The adsorption mechanism followed the pseudo second order, the Freundlich, and the Temkin models. The results indicated that the adsorption process is reliant on chemical interactions. It was also governed by intraparticular diffusion and other kinetic phenomena. Full article

The water distribution system is a critical infrastructure aiming to deliver safe and clean drinking water, with pipeline materials significantly influencing water quality and efficiency. One critical factor in selecting pipeline materials is the potential for biofilm formation on the inner surfaces of pipes. This study investigates the effects of three iron salts—iron (II) sulfate heptahydrate, iron (III) nitrate nonahydrate, and iron (III) chloride on biofilm formation by Escherichia coli and Enterococcus faecalis in pipeline environments, focusing on water distribution systems. While previous research has examined the effects of iron on various bacterial species, there are limited data on E. coli and E. faecalis biofilm formation in the context of water distribution systems. Results reveal that iron (III) chloride significantly inhibited E. coli biofilm formation by up to 80%, while E. faecalis biofilm growth was promoted by iron (II) sulfate heptahydrate, with an increase of approximately 45%. These findings underscore the critical role of managing iron concentrations to mitigate biofilm-related issues, which influence water quality, infrastructure durability, and microbial resistance. The study highlights the importance of integrating these insights into sustainable water management practices and advancing pipeline material innovations to enhance public health and environmental resilience. Full article

Developing an efficient recycling route for spent single-use medical devices is essential for recovering precious metals. The proposed complete hydrometallurgical route goes through the initial pyrolysis and acid digestion steps, expanding upon our previous relevant work in the field, followed by solvent extraction, stripping, and precipitation procedures. In this study, a complete hydrometallurgical process was developed for the recovery of gold, platinum, iridium, and tantalum, separating them from other metals, i.e., from iron, chromium, and nickel, also present in the examined medical devices, i.e., (i) diagnostic electrophysiology catheters, containing gold, (ii) diagnostic guide wires, containing platinum and iridium alloys, and (iii) self-expanding stents, containing tantalum. This study reports the experimental results of selecting an efficient extractant, stripping, and precipitation agent, along with the effects of key factors that influence each consecutive step of the process, i.e., agent concentration, aqueous to organic phase ratio, contact time, and pH, using simulated metal solutions and also applying the obtained optimal conditions to the treatment of real sample solutions. For the selective separation of gold, Aliquat 336 was used to extract it in the organic phase; it was then stripped using a thiourea solution and precipitated by utilizing an iron sulfate (II) solution and proper pH adjustment. The selective separation of platinum was achieved by using Aliquat 336 for the organic phase extraction and a perchlorate acid solution for stripping it back into the aqueous solution and adding a sodium bromate solution to precipitate it. Due to the similar chemical behavior, the selective recovery of iridium followed the same processes as that of platinum, and the separation between them was achieved through selective precipitation, as heating the solution and adjusting the pH value resulted in the selective precipitation of iridium. Lastly, the selective recovery of tantalum consists of extraction by using Alamine 336, then stripping it back to the aqueous phase by using sodium chloride, and precipitation by using potassium salt solution and proper pH adjustment. A total recovery of 88% for Au, 86% for Pt, 84% for Ir, and 80% for Ta was obtained, thus achieving a high uptake of precious metals from the examined real spent/waste samples. Full article

Crystal violet (CV) is an organic chloride salt and a triphenylmethane dye commonly used in the textile processing industry, also being used as a disinfectant and a biomedical stain. Although CV is widely used, it is carcinogenic to humans and is retained by industrial-produced effluent for an extended period. The different types of metal oxide (MO_x) have impressive photocatalytic properties, allowing them to be utilized for pollutant degradation. The role of the photocatalyst is to facilitate oxidation and reduction processes by trapping light energy. In this study, we investigated different types of metal oxides, such as titanium dioxide (TiO₂), zinc oxide (ZnO), zirconium dioxide (ZrO₂), iron (III) oxide (Fe₂O₃), copper (II) oxide (CuO), copper (I) oxide (Cu₂O), and niobium pentoxide (Nb₂O₅) for the CV decomposition reaction at ambient conditions. For characterization, BET and Raman spectroscopy were applied, providing findings showing that the surface area of the anatase TiO₂ and ZnO were 5 m²/g and 12.1 m²/g, respectively. The activity tests over TiO₂ and ZnO catalysts revealed that up to ~98% of the dye could be decomposed under UV irradiation in <2 h. The decomposition of CV is directly influenced by various factors, such as the types of MO_x, the band gap–water splitting relationship, and the recombination rate of electron holes. Full article

Through the implementation of a one-pot strategy, five examples of non-symmetrical [N,N-diaryl-11-phenyl-1,2,3,7,8,9,10-heptahydrocyclohepta[b]quinoline-4,6-diimine]iron(II) chloride complexes (aryl = 2,6-Me₂Ph Fe1, 2,6-Et₂Ph Fe2, 2,6-i-Pr₂Ph Fe3, 2,4,6-Me₃Ph Fe4, and 2,6-Et₂-4-MePh Fe5), incorporating fused six- and seven-membered carbocyclic rings and appended with a remote para-phenyl group, were readily prepared. The molecular structures of Fe2 and Fe3 emphasize the variation in fused ring size and the skewed disposition of the para-phenyl group present in the N′,N,N″-ligand support. Upon activation with MAO or MMAO, Fe1–Fe5 all showed high catalytic activity for ethylene polymerization, with an exceptional level of 35.92 × 10⁶ g (PE) mol⁻¹ (Fe) h⁻¹ seen for mesityl-substituted Fe4/MMAO operating at 60 °C. All catalysts generated highly linear polyethylene with good control of the polymer molecular weight achievable via straightforward manipulation of run temperature. Typically, low molecular weight polymers with narrow dispersity (M_w/M_n = 1.5) were produced at 80 °C (MMAO: 3.7 kg mol⁻¹ and MAO: 4.9 kg mol⁻¹), while at temperatures between 40 °C and 50 °C, moderate molecular weight polymers were obtained (MMAO: 35.6–51.6 kg mol⁻¹ and MAO: 72.4–95.5 kg mol⁻¹). Moreover, analysis of these polyethylenes by ¹H and ¹³C NMR spectroscopy highlighted the role played by both β-H elimination and chain transfer to aluminum during chain termination, with the highest rate of β-H elimination seen at 60 °C for the MMAO-activated system and 70 °C for the MAO system. Full article

We have described a new route for the preparation of partially methylated polygalacturonic acid containing hydrolyzed (acidic) and unhydrolyzed (methyl esterified) carboxylate groups in a ratio of 1:1 (PGA, compound 1), and one of its basic Fe^III—salts (compound 2) with a ~1:2 Fe^III:GA stoichiometry (GA means galacturonic acid and methylated galacturonic acid units). The partially hydrolyzed pectin was transformed into compound 1 with the use of double ion exchange with a strongly acidic macroreticular sulfonated styrene–divinylbenzene copolymer as a hydrogen ion source. The reaction of compound 1 with FeCl₃ resulted in compound 2. Compound 2 has a polymeric nature and contains binuclear Fe^III(µ-O)(µ-OH)Fe^III core units with two kinds of distorted octahedral iron geometries. The salt-forming acidic and methylated GA units of compound 1 are coordinated to Fe^III centers in asymmetric bidentate-chelating and -bridging (via C=O group and glycosidic oxygen) modes, respectively. Two kinds of outer-sphere chloride anions were also detected by XPS in various chemical environments fixed by different sets of hydrogen bonds. We also observed a partial reduction of Fe^III into Fe^II due to the ring-opening of the chain-end GA units of compound 1. This reaction provides a new route to determine the number of chain-ends in compound 2, and with the use of the number of GA units calculated from charge neutrality, the average length of these chains and the average molecular weight were also determined. The average molecular weight of the partially methylated polygalacturonic acid used in the industrial-scale production of commercial anti-anemic iron–polygalacturonate agents was ~50,000 g/mol. Compound 2 was also characterized by IR, Mössbauer, and X-ray photoelectron spectroscopy, and magnetic susceptibility measurements. These results on the structure and average molecular weight of basic iron(III) polygalacturonate provide a tool to design Fe-PGA complexes with tuned iron-releasing properties. Full article

This study investigates the performance of two bentonite materials, specifically MX-80 (Na-bentonite) and FEBEX (Ca-Mg-Na-bentonite), employed as engineered barriers in deep geological disposal facilities for the isolation of high-level radioactive waste, contained in metallic canisters. Experiments conducted at the laboratory scale focused on the interaction of these bentonites with FeCl₂ powder, used as a soluble iron source, to observe enhanced alteration of the bentonite. The experiments were carried out under a hydrothermal gradient. A dominant Na-Cl-SO₄ saline solution was put in contact with the compacted bentonites from the top, while a constant temperature of 100 °C was maintained at the bottom using a heater in contact with the layer of FeCl₂. The experimental cells were examined after six months of interaction. Various changes in the physical and chemical properties of the bentonites were observed. An increase in the water content, a reduction in the specific surface area and cation exchange capacity, changes in the distribution of aqueous species, and the formation of secondary minerals were observed. Reaction products formed at the bentonite interface with FeCl₂, primarily comprising akaganeite, goethite, and hematite. The smectites showed evident structural modifications, with an enrichment in iron content, and a shift in the exchangeable ion distribution in the case of MX-80 bentonite. This work provides valuable insights into the complex interactions between bentonite barriers and materials that dissolve iron, serving as proxies for deep geological disposal environments and indicating the potential long-term behavior, taking into account higher concentrations of dissolved iron than those expected in a real repository. Full article

Determining the antioxidant abilities and enzyme inhibition profiles of medicinally important plants and their oils is of great importance for a healthy life and the treatment of some common global diseases. Kiwifruit (Actinidia deliciosa) oil was examined and researched using several bioanalytical methods comprehensively for the first time in this research to determine its antioxidant, antiglaucoma, antidiabetic and anti-Alzheimer’s capabilities. Additionally, the kiwifruit oil inhibitory effects on acetylcholinesterase (AChE), carbonic anhydrase II (CA II), and α-amylase, which are linked to a number of metabolic illnesses, were established. Furthermore, LC-HRMS analysis was used to assess the phenolic content of kiwifruit oil. It came to light that kiwifruit oil contained 26 different phenolic compounds. According to the LC-HRMS findings, kiwifruit oil is abundant in apigenin (74.24 mg/L oil), epigallocatechin (12.89 mg/L oil), caryophyllene oxide (12.89 mg/L oil), and luteolin (5.49 mg/L oil). In addition, GC-MS and GC-FID studies were used to ascertain the quantity and chemical composition of the essential oils contained in kiwifruit oil. Squalene (53.04%), linoleoyl chloride (20.28%), linoleic acid (2.67%), and palmitic acid (1.54%) were the most abundant compounds in kiwifruit oil. For radical scavenging activities of kiwifruit oil, 1,1-diphenyl-2-picryl-hydrazil (DPPH^•) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS^•+) radicals scavenging techniques were examined. These methods effectively demonstrated the potent radical scavenging properties of kiwifruit oil (IC₅₀: 48.55 μg/mL for DPPH^•, and IC₅₀: 77.00 μg/mL for ABTS^•+ scavenging). Also, for reducing capabilities, iron (Fe³⁺), copper (Cu²⁺), and Fe³⁺-2,4,6-tri(2-pyridyl)-S-triazine (TPTZ) reducing abilities were studied. Moreover, kiwifruit oil showed a considerable inhibition effect towards hCA II (IC₅₀: 505.83 μg/mL), AChE (IC₅₀: 12.80 μg/mL), and α-amylase (IC₅₀: 421.02 μg/mL). The results revealed that the use of kiwifruit oil in a pharmaceutical procedure has very important effects due to its antioxidant, anti-Alzheimer, antidiabetic, and antiglaucoma effects. Full article

Metallic iron (Fe⁰) is a reactive material for treating polluted water. The effect of water salinity on the efficiency of Fe⁰-based remediation systems is not yet established. This work aims to clarify the reasons why Cl⁻ ions are often reported to improve the efficiency of Fe⁰/H₂O remediation systems. Quiescent batch experiments were carried out to characterize the effect of chloride (Cl⁻) ions on the efficiency of methylene blue (MB) discoloration in the presence of Fe⁰. Cl⁻ was used in the form of NaCl at concentrations ranging from 0 to 40 g L⁻¹. The MB concentration was 10 mg L⁻¹, the Fe⁰ loading was 5 g L⁻¹, and the duration of the experiment varied from 2 to 46 days. Four different Fe⁰ materials were tested in parallel experiments. Tests with different NaCl levels were performed in parallel with three other organic dyes: Methyl orange (MO), orange II (OII), and reactive red 120 (RR 120). The results clearly show that the presence of Cl⁻ reduces the extent of dye discoloration in all systems investigated. The efficiency of the dyes increased in the order MB < MO < RR 120 < OII. In systems with varying NaCl concentrations, dye discoloration initially decreases with increasing NaCl and slightly increases for [NaCl] > 30 g L⁻¹. However, the extent of dye discoloration for [NaCl] = 40 g L⁻¹ remains much lower than for the system with [NaCl] = 0 g L⁻¹. The results clearly demonstrate that the presence of Cl⁻ fundamentally delays the process of contaminant removal in Fe⁰/H₂O systems, thus improving the understanding of the contaminant interactions in Fe⁰-based remediation systems. These results also suggest that the effects of other inorganic anions on the efficiency of Fe⁰/H₂O systems should be revisited for the design of field applications. Full article

The influence of plasma-reduction treatment on iron and copper compounds at different oxidation states was investigated in this study. For this purpose, reduction experiments were carried out with artificially generated patina on metal sheets and with metal salt crystals of iron(II) sulfate (FeSO₄), iron(III) chloride (FeCl₃), and copper(II) chloride (CuCl₂), as well as with the metal salt thin films of these compounds. All the experiments were carried out under cold low-pressure microwave plasma conditions; the main focus was on plasma reduction at a low pressure in order to evaluate an implementable process in a parylene-coating device. Usually, plasma is used within the parylene-coating process as a supporting tool for adhesion improvement and micro-cleaning efforts. This article offers another useful application for implementing plasma treatment as a reactive medium in order to apply different functionalities by an alteration in the oxidation state. The effect of microwave plasmas on metal surfaces and metal composite materials has been widely studied. In contrast, this work deals with metal salt surfaces generated from a solution and the influence of microwave plasma on metal chlorides and sulfates. While the plasma reduction of metal compounds commonly succeeds with hydrogen-containing plasmas at high temperatures, this study shows a new reduction process that reduces iron salts at temperatures between 30 and 50 °C. A novelty of this study is the alteration in the redox state of the base and noble metal materials within a parylene-coating device with the help of an implemented microwave generator. Another novelty of this study is treating metal salt thin layers for reduction purposes in order to provide the opportunity to include subsequent coating experiments to create parylene metal multilayers. Another new aspect of this study is the adapted reduction process of thin metal salt layers consisting of either noble or base metals, with an air plasma pre-treatment prior to the hydrogen-containing plasma-reduction procedure. Full article

The assignments structures of the four 1:1 pipemidic acid (pipH)–magnesium(II), calcium(II), zinc(II), and iron(III) complexes, [Mg(pip)(H₂O)₃(Cl)].6H₂O, [Ca(pip)(H₂O)₃(Cl)].2H₂O, [Zn(pip)(H₂O)₃(Cl)].4H₂O, and [Fe(pip)(H₂O)₂(Cl)₂].6H₂O, (where pip = deprotonated pipemidic), were synthesized through the chemical reactions of MgCl₂.6H₂O, CaCl₂.2H₂O, ZnCl₂, and FeCl₃.6H₂O metal salt chlorides with pipH chemotherapeutic agent ligand in a methanolic solvent. The microanalytical analysis CHN, conductance, (infrared (FTIR) and electronic (UV–Vis.)) spectra, and thermogravimetric measurements (TG) have been utilized to discuss the solid isolated complexes. The X-ray powder diffraction (XRD) analysis and the transmission electron microscopy (TEM) confirm the nanostructured form of the synthesized pip complexes. The deprotonated pipH ligand is coordinated to Mg(II), Ca(II), Zn(II), and Fe(III) metal ions through the two oxygen atoms of the carbonyl (quinolone group) and carboxylic group. The thermodynamic parameters (energy, E*), (entropy, ΔS*), (enthalpy, ΔH*), and (Gibbs free energy, ΔG*) of activation have been estimated based on thermogravimetric curves using “Coats–Redfern and Horowitz–Metzeger non–isothermal” methods. Full article

Mechanically robust ferrogels with high self-healing ability might change the design of soft materials used in strain sensing. Herein, a robust, stretchable, magneto-responsive, notch insensitive, ionic conductive nanochitin ferrogel was fabricated with both autonomous self-healing and needed resilience for strain sensing application without the need for additional irreversible static chemical crosslinks. For this purpose, ferric (III) chloride hexahydrate and ferrous (II) chloride as the iron source were initially co-precipitated to create magnetic nanochitin and the co-precipitation was confirmed by FTIR and microscopic images. After that, the ferrogels were fabricated by graft copolymerisation of acrylic acid-g-starch with a monomer/starch weight ratio of 1.5. Ammonium persulfate and magnetic nanochitin were employed as the initiator and crosslinking/nano-reinforcing agents, respectively. The ensuing magnetic nanochitin ferrogel provided not only the ability to measure strain in real-time under external magnetic actuation but also the ability to heal itself without any external stimulus. The ferrogel may also be used as a stylus for a touch-screen device. Based on our findings, our research has promising implications for the rational design of multifunctional hydrogels, which might be used in applications such as flexible and soft strain sensors, health monitoring, and soft robotics. Full article