Search Results (86)

Nanotechnology plays an increasingly important role in the economy and human life, which means that more and more amounts of nanosubstances, including nanoparticles of metal oxides, together with wastewater, end up in the environment. This study aimed to study the impact of iron(III) oxide nanoparticles (n-Fe₂O₃), which have magnetic properties, on the efficiency of the Anammox wastewater treatment process. The results indicate that n-Fe₂O₃ in the range of low concentrations may have a positive effect on nitrogen metabolism, increasing the efficiency of NH₄-N removal to 98% in 120 min and at 30 °C. During the first 30 min of the process, when almost anaerobic conditions arose, nanoparticles of Fe₂O₃, stabilized the system by producing ROS. However, a constant control of TOC and pH is necessary because of the constant increase in the amount of organic compounds and H⁺ ions during the reaction. However, a longer contact of n-Fe₂O₃ with biomass causes the efficiency to decrease, and, as a result, the efficiency is lower compared to the system containing only Anammox. 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

Chromium-containing wastewater poses severe threats to ecosystems and human health due to the high toxicity of hexavalent chromium (Cr(VI)). Although iron oxide nanoparticles (IONPs) show promise for Cr(VI) removal, their practical application is hindered by challenges in recovery and reuse. Herein, a novel three-dimensional porous nanocomposite, Artemia cyst shell biochar-supported iron oxide nanoparticles (ACSC@ IONP), was synthesized via synchronous pyrolysis of Fe³⁺-impregnated Artemia cyst shells (ACSs) and in situ reduction of iron. The optimized composite C@Fe-3, prepared with 1 mol/L Fe³⁺ and pyrolyzed at 450 °C for 5 h, exhibited rapid removal equilibrium within 5–10 min for both Cr(VI) and total chromium (Cr(total)), attributed to synergistic reduction of Cr(VI) to Cr(III) and adsorption of Cr(VI) and Cr(III). The maximum Cr(total) adsorption capacity was 110.1 mg/g at pH 2, as determined by the Sips isothermal model for heterogeneous adsorption. Competitive experiments demonstrated robust selectivity for Cr(VI) removal even under a 64-fold excess of competing anions, with an interference order of SO₄²⁻ > NO₃⁻ > Cl⁻. Remarkably, C@Fe-3 retained 65% Cr(VI) removal efficiency after four adsorption–desorption cycles. This study provides a scalable and eco-friendly strategy for fabricating reusable adsorbents with dual functionality for chromium remediation. Full article

Magnetic iron oxide (II,III) nanoparticles (MNPs) are highly interested in biomedicine. However, their application is limited by oxidation, aggregation, rapid clearance from the body, and poor biodistribution. Coating by human serum albumin (HSA), the predominant blood plasma protein, can significantly influence properties, prolong circulation half-life, and enhance tumor capture efficiency. Here, we report the synthesis of oleic acid and Tween20-coated MNPs and their interaction with HSA. The influence of albumin coating on MNP size, zeta potential, aggregation ability, and toxicity was studied. The particles were characterized by dynamic light scattering, transmission electron microscopy, and Fourier transform infrared spectroscopy methods. The nanoparticles’ relaxivities (r₁ and r₂) were assessed under a magnetic field of 1.88 T to evaluate their performance in MRI applications. The anticancer drug doxorubicin (DOX) loading capacity of up to 725 µg/mg for albumin-coated MNPs was determined. DOX-loaded MNPs displayed pH-sensitive drug release during acidic conditions. The series of DOX-loaded nanocomposites indicated inhibition of A549 cell lines, and the IC₅₀ values were evaluated. This research underscores the utility of HSA-coated MNPs in enhancing the efficacy and stability of drug delivery systems in biomedicine. Full article

While microparticles can be removed by a filtration step at a drinking water treatment plant (DWTP), engineered nanoparticles (ENPs), which are widely used in industry, commerce and households, pose a major problem due to their special properties, e.g., size, reactivity and polarity. In addition, many ENPs exhibit toxic potential, which makes their presence in drinking water undesirable. Therefore, this study investigated the removal of ENPs in the laboratory and at a pilot-scale DWTP. Eight ENPs were synthesized and tested for stability in different types of water. Only three of them were stable in natural water: cetyltrimethylammonium bromide-coated gold (CTAB/AuNPs), polyvinylpyrrolidone-stabilized gold and silver nanoparticles (PVP/AuNPs, PVP/AgNPs). Their retention on quartz sand, silica gel and fresh anthracite was low, but CTAB/AuNPs could be retained on fresh river sand and thus should not overcome riverbank filtration, while PVP/AuNPs and PVP/AgNPs showed no retention and may be present in raw water. During ozonation, PVP/AuNPs remained stable while PVP/AgNPs were partially degraded. The advanced oxidation process (AOP) was less effective than ozone. PVP/AgNPs were almost completely retained on the pilot plant anthracite sand filter coated with manganese(IV) oxide and ferrihydrite from raw water treatment. PVP/AuNPs passed the filter with no retention. In contrast to PVP/AuNPs, PVP/AgNPs and CTAB/AuNPs were also retained on activated carbon. The integration of a flocculation step with iron(III) salts can improve ENP removal, with PVP/AuNPs requiring higher flocculant doses than PVP/AgNPs. PVP/AuNPs, in particular, are well-suited for testing the effectiveness of water treatment. Further data on the occurrence of stable ENPs in raw water and their behavior during water treatment are needed to perform a risk assessment and derive the measures. Full article

In this study, magnetic binary/ternary Zn_xCo_1−xFe₂O₄ (x = 0, 0.5, 1) nanoparticles were synthesized using a straightforward one-step microwave technique. To produce the Zn_xCo_1−xFe₂O₄ nanoparticles, iron (III) nitrate nonahydrate, zinc nitrate hexahydrate, and cobalt nitrate hexahydrate were used as metal sources, with urea used as the fuel and ammonium nitrate as the oxidizer. These materials were combined in an alumina crucible covered by a CuO jacket to absorb microwave energy and facilitate calcination. The thermal treatment involved placing the alumina crucible in a domestic microwave oven at 450 W for 30 min. The key strengths of this experimental strategy include its simplicity, cost-effectiveness, and rapidity, aligning with green chemistry principles. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, a vibrating sample magnetometer (VSM), and Brunauer–Emmett–Teller (BET) analysis. XRD analysis confirmed the presence of the pure ferrite nanocrystalline phase. Scanning electron microscopy (SEM), employed with energy-dispersive X-ray spectroscopy (EDS), was used to study the surface morphology and analyze the elemental composition. The SEM analysis revealed that the synthesized magnetic nanoparticles had particle sizes ranging from 30 to 50 nm. Furthermore, we explored the potential use of these magnetic nanoparticles as photocatalysts for degrading organic pollutants such as methylene blue in aqueous solutions. Full article

Iron oxide nanoparticles (IONs) are extensively used in biomedical applications due to their unique magnetic properties. This study optimized ION synthesis via the co-precipitation method, exploring the impact of the reactant concentrations (Fe(II) and Fe(III)), NaOH concentration, temperature (30 °C–80 °C), stirring speed (0–1000 rpm), and dosing rate (10–600 s) on particle size and growth. Using small-angle X-ray scattering (SAXS), we observed, for example, that higher temperatures (e.g., 67 °C compared with 53 °C) led to a 50% increase in particle size, while the stirring speed and NaOH concentration also influenced nucleation and aggregation. These results provide comprehensive insights into optimizing synthetic conditions for targeted applications in biomedical fields, such as drug delivery and magnetic resonance imaging (MRI), where precise control over nanoparticle size and properties is crucial. Full article

In this study, we achieved the biosynthesis of novel 7–8 nm iron-oxide nanoparticles in the presence of different concentrations (5 to 50% w/v) of commercial white quinoa extract. Initially, quinoa extract was prepared at various concentrations by a purification route. The biosynthesis optimization was systematically monitored by X-ray diffraction, and the Rietveld quantitative analysis showed the presence of goethite (5 to 10 wt.%) and maghemite phases. The first phase disappeared upon increasing the organic loading (40 and 50% w/v). The organic loading was corroborated by thermogravimetric measurements, and it increased with quinoa extract concentration. Its use reduces the amount of precipitation agent at high quinoa extract concentrations with the formation of magnetic nanoparticles with hard ferrimagnetic character (42 and 11 emu g⁻¹). The enrichment of hydroxyl groups and the negative zeta potential above pH = 7 were corroborated by a reduction in the point of zero charge in all the samples. For alkaline values, the zeta potential values were above the stability range, indicating highly stable chemical species. The evidence of hydroxyl and amide functionalization was qualitatively observed using infrared analysis, which showed that the carboxyl (quercetin/kaempferol), amide I, and amide III chemical groups are retained after biosynthesis. The resultant biosynthesized samples can find applications in environmental remediation due to the affinity of the chemical agents present on the particle surfaces and easy-to-handle them magnetically. Full article

Much progress has been made in the determination of As (III), while numerous electrochemical sensors based on metal nanomaterials with significant sensitivity and precision have been developed. However, further research is still required to achieve rapid detection and avoid interference from other metal ions (especially copper ions). In this study, bimetallic AuPt nanoparticles are electrochemically modified with screen printing electrodes. What’s more, L-cysteine also self-assembles with AuNPs through Au-S bond to enhance the electrochemical performance. To overcome the interference of Cu (II) in the sensing process, the reduced iron powder was chosen to remove Cu (II) and other oxidizing organics in aqueous solutions. The lowest detectable amount is 0.139 ppb, a linear range of 1~50 ppb with superlative stability by differential pulse anodic stripping voltammetry. Fortunately, the reduced iron powder could eliminate the Cu (II) with no effect on the As (III) signal. Full article

Hybrid material-derived adsorbents have shown a great applicable efficiency in various fields, including industrial uses and environmental remediation. Herein, zinc oxide nanoparticle modified with carbon (ZnO-C) was fabricated and utilized for wastewater treatment through the adsorption of Zn(II), Cd(II), Co(II), and Mn(II). The surface and structural characteristics were examined using TEM, SEM, XRD, FTIR spectroscopy, EDS, and the BET surface area. Kinetics and equilibrium investigations were applied to optimize the adsorptive removal of Zn(II), Cd(II), Co(II), and Mn(II) onto ZnO-C. The results indicated that the formation of ZnO-C in crystalline sphere-like granules with a nano-size between 16 and 68 nm together with carbon matrix. In addition, the spherical granules of zinc oxide were gathered to form clusters. FTIR spectroscopy indicated that the ZnO-C surface was rich with OH groups and ZnO. The adsorption capacity 215, 213, 206, and 231 mg/g for Zn(II), Cd(II), Co(II), and Mn(II), respectively, at the optimal conditions pH between 5 and 6, a contact time of 180 min, and an adsorbent dose of 0.1 g/L. The adsorptive removal data modeling for the uptake of Zn(II), Cd(II), Co(II), and Mn(II) onto ZnO-C showed agreement with the assumption of the pseudo-second-order kinetic model and the Freundlich isotherm, suggesting a fast adsorption rate and a multilayered mechanism. The achieved adsorption capacity using the prepared ZnO-C was more effective compared to ZnO, carbon, Fe₃O₄, and Fe₃O₄-C. Real wastewater samples were applied, including valley water, industrial wastewater, and rain wastewater, and evaluated for the applicable uptake of Zn(II), Cd(II), Co(II), and Mn(II) using ZnO-C and Fe₃O₄-C with effective removal efficiency. Full article

Graphene oxide and its magnetic nanoparticle-based composites are a well-known tool to remove heavy metals from wastewater. Unfortunately, one of the major issues in handling such small particles consists of their difficult removal from treated wastewater (even when their magnetic properties are exploited), due to their very small diameter. One possible way to overcome this problem is to embed them in a macroscopic biopolymer matrix, such as alginate or chitosan beads. In this way, the adsorbent becomes easier to handle and can be used to build, for example, a packed column, as in a traditional industrial adsorber. In this work, the removal performances of two different embedded magnetic nanocomposite adsorbents (MNAs) are discussed. The first type of MNA is based on ferrite magnetic nanoparticles (MNPs) generated by coprecipitation using iron(II/III) salts and ammonium hydroxide, while the second is based on a 2D material composed of MNP-decorated graphene oxide. Both MNAs were embedded in cross-linked alginate beads and used to treat artificial water contaminated with chromium(III), nickel(II), and copper(II) in different concentrations. The yield of removal and differences between MNAs and non-embedded magnetic nanomaterials are also discussed. From the results, it was found that the time to reach the adsorption equilibrium is higher when compared to that of the nanomaterials only, due to the lower surface/volume ratio of the beads, but the adsorption capacity is higher, due to the additional interaction with alginate. Full article

This study synthesizes magnetic iron oxide nanoparticles from agro-waste sweet pepper extract, exploring their potential as antioxidant additives and in food preservation. Iron (III) chloride hexahydrate is the precursor, with sweet pepper extract as both a reducing and capping agent at pH 7.5. Characterization techniques, including microscopy and spectroscopy, analyze the sweet pepper extract-magnetic iron oxide nanoparticles. Antioxidant capacities against 2,2-diphenyl-1-picrylhydrazyl are assessed, incorporating nanoparticles into banana-based bioplastic for grape preservation. Microscopy reveals cubic and quasi-spherical structures, and spectroscopy confirms functional groups, including Fe–O bonds. X-ray diffraction identifies cubic and monoclinic magnetite with a monoclinic hematite presence. Sweet pepper extract exhibits 100% inhibitory activity in 20 min, while sweet pepper extract-magnetic iron oxide nanoparticles show an IC₅₀ of 128.1 µg/mL. Furthermore, these nanoparticles, stabilized with banana-based bioplastic, effectively preserve grapes, resulting in a 27.4% lower weight loss rate after 144 h compared to the control group (34.6%). This pioneering study encourages institutional research into the natural antioxidant properties of agro-waste sweet pepper combined with magnetic iron and other metal oxide nanoparticles, offering sustainable solutions for nanopackaging and food preservation. Current research focuses on refining experimental parameters and investigating diverse applications for sweet pepper extract-magnetic iron oxide nanoparticles in varied contexts. Full article

Magnetite-based nanoparticles are of constant interest in the scientific community as potential systems for biomedical applications. Over the years, the ability to synthesize diverse systems based on iron (II, III) oxide nanoparticles has been mastered to maximize their potential effectiveness in the targeted delivery of active substances in cancer therapy. The present review explores recent literature findings that detail various magnetic nanosystems. These encompass straightforward designs featuring a polymer coating on the magnetic core and more intricate matrices for delivering chemotherapeutic drugs. This paper emphasizes novel synthetic approaches that impact the efficacy and progress of anticancer investigations, specifically targeting a particular cancer type. The research also delves into combinations with alternative treatment methods and diagnostic approaches. Additionally, it highlights a critical aspect—the interaction with cells—identifying it as the least developed aspect in current research on these systems. Full article

This study details the synthesis of tomato extract–magnetic iron oxide nanoparticles (TEx-MIONPs), focusing on the antioxidant capacity and food preservation applications. Utilizing key reagents, including 98% iron (III) chloride hexahydrate, a controlled process yielded TEx-MIONPs. The characterization involved X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). XRD analysis revealed a predominant cubic magnetite structure. TEM and SEM depicted diverse morphologies, such as ultrasmall cubic and quasi-spherical structures. FTIR spectroscopy confirmed Fe–O bonds in a mixed phase of Fe₂O₃ and Fe₃O₄. Antioxidant activity assessment showcased the potent scavenging effects of TEx and TEx-MIONPs against DPPH free radicals, with 100% inhibition after 20 min and an IC₅₀ of about 137 µg/mL, respectively. Furthermore, TEx-MIONPs, when stabilized with banana-based bioplastic and utilized as nanocoating preservation materials, demonstrated efficacy in grape preservation by exhibiting a lower weight loss rate compared to the control group over six days. Specifically, the weight loss rate for preserved grapes was 28.6% on day 6, contrasting with 34.6% for the control. This pioneering study amalgamates the natural antioxidant properties of tomatoes with the enhanced characteristics of magnetic iron oxide nanoparticles, offering sustainable solutions for food preservation and nanopackaging. Ongoing research aims to refine the experimental conditions and explore the broader applications of TEx-MIONPs in various contexts. Full article

Multifunctional materials based on carbon xerogel (CX) with embedded bismuth (Bi) and iron (Fe) nanoparticles are tested for ultrasensitive amperometric detection of lead cation (Pb²⁺) and hydrogen peroxide (H₂O₂). The prepared CXBiFe-T nanocomposites were annealed at different pyrolysis temperatures (T, between 600 and 1050 °C) and characterized by X-ray diffraction (XRD), Raman spectroscopy, N₂ adsorption, dynamic light scattering (DLS), and electron microscopies (SEM/EDX and TEM). Electrochemical impedance spectroscopy (EIS) and square wave anodic stripping voltammetry (SWV) performed at glassy carbon (GC) electrodes modified with chitosan (Chi)-CXBiFe-T evidenced that GC/Chi-CXBiFe-1050 electrodes exhibit excellent analytical behavior for Pb²⁺ and H₂O₂ amperometric detection: high sensitivity for Pb²⁺ (9.2·10⁵ µA/µM) and outstanding limits of detection (97 fM, signal-to-noise ratio 3) for Pb²⁺, and remarkable for H₂O₂ (2.51 µM). The notable improvements were found to be favored by the increase in pyrolysis temperature. Multi-scale parameters such as (i) graphitization, densification of carbon support, and oxide nanoparticle reduction and purification were considered key aspects in the correlation between material properties and electrochemical response, followed by other effects such as (ii) average nanoparticle and Voronoi domain dimensions and (iii) average CXBiFe-T aggregate dimension. Full article