Search Results (2,580)

Advanced oxidation processes using porphyrin-based heterogeneous catalysts hold promise for removing hazardous pollutants from wastewater. Their high visible-light absorption coefficients enable absorption of light from the solar spectrum. Moreover, their conjugated aromatic skeletons and intrinsic electronic properties facilitate the delocalization of photogenerated electrons during photodegradation. Delaying the recombination of photogenerated electron–hole pairs by introducing specific materials increases efficiency, as separated charges have more time to participate in redox reactions, boosting photocatalytic activities. However, applying these photocatalysts for wastewater treatment is challenging owing to facile agglomeration, deactivation, and recovery of the photocatalyst for reuse, which can significantly increase the overall cost. Therefore, new photocatalytic systems comprising porphyrin molecules must be developed. For this purpose, porphyrins can be conjugated to nanomaterials to create hybrid materials with photocatalytic efficiencies superior to those of free-standing starting porphyrins. Various transition metal oxides (TiO₂, ZnO, and Fe₃O₄) nanoparticles, main-group-element oxides (Al₂O₃ and SiO₂) nanoparticles, metal plasmons (silver nanoparticles), carbon-based platforms (graphene, graphene oxide, and g-C₃N₄), and polymer matrices have been used as nanostructured solid supports for the successful fabrication of porphyrin-conjugated hybrid materials. The conjugation of porphyrin molecules to solid supports improves the photocatalytic degradation activity in terms of visible-light conversion ability, recyclability, active porous sites, substrate mobility, separation of photogenerated charge species, recovery for reuse, and chemical stability, along with preventing the generation of secondary pollution. This review discusses the ongoing development of porphyrin-conjugated hybrid nanomaterials for the heterogeneous photocatalytic degradation of organic dyes, pharmaceutical pollutants, heavy metals, pesticides, and human care in water. Several important results and advancements in the field allow for a more efficient wastewater remediation process. Full article

In this work, four different magnetic Fe₃O₄ nanoparticles are prepared via solvothermal method. According to the morphology, the products can be divided into flower-like Fe₃O₄ (F-Fe₃O₄), solid spherical Fe₃O₄ (S-Fe₃O₄), hollow spherical Fe₃O₄ (HO-Fe₃O₄), and hexahedral Fe₃O₄ (HE-Fe₃O₄). A set of measurements is performed to confirm the structure, composition, and pore properties of the obtained materials. The catalytic activities of the prepared materials are examined and compared. The results prove that the four materials have an intrinsic catalytic property. HO-Fe₃O₄ ranks first in the catalytic activity mainly due to its large surface area and reasonable element composition. The maximum specific saturation magnetization and specific surface area of HO-Fe₃O₄ are 72.94 emu/g and 42.60 m²/g. Fe²⁺/Fe³⁺ in HO-Fe₃O₄ is 51.5%. It is found that HO-Fe₃O₄ possesses fantastic stability and perfect reproducibility as it is used as a catalyst several times without significant loss in its activity. Full article

Background: Chemodynamic therapy (CDT) and photothermal therapy (PTT) based on nanomaterials have garnered widespread attention in cancer treatment. However, most single-modal nanotherapeutics suffer from limited therapeutic efficacy. Methods: Herein, a magnetic mesoporous composite nanoparticle, Fe₃O₄@MSN@PDA-HA-FA, is successfully fabricated, with Fe₃O₄ nanoparticles as the magnetic core; mesoporous silica nanoparticles (MSNs) as the mesoporous shell; and dopamine hydrochloride (DA·HCl), hyaluronic acid (HA), and folic acid (FA) as the functional ligands. Results: Notably, this composite serves as both an efficient photothermal converter and a chemodynamic promoter, enhancing hydroxyl radical (·OH) generation and improving PTT efficacy. Under near-infrared (NIR) light irradiation, Fe₃O₄@MSN@PDA-HA-FA exhibits high photothermal conversion and heat transfer efficiencies. The Fe²⁺ ions in Fe₃O₄ enable a Fenton reaction-mediated conversion of endogenous hydrogen peroxide (H₂O₂) into ·OH for CDT. Additionally, the MSNs provide a substantial drug-loading capacity, while the HA and FA provide additional surface functionalities that can modulate the nano-bio interactions and improve colloidal stability. Conclusions: In vitro experiments validate the synergistic therapeutic efficacy of PTT, CDT, and chemotherapy. This study demonstrates that Fe₃O₄@MSN@PDA-HA-FA exhibits antitumor efficacy, laying a promising foundation for its potential clinical translation in cancer treatment. Full article

This manuscript reports a green approach for producing multifunctional acrylic fabrics co-decorated with Fe₃O₄ and Ag nanoparticles using Brachychiton populneus extract. Acrylic fabric was first amidoxime-functionalized to enable strong anchoring of Fe₃O₄ nanoparticles, followed by in situ deposition of AgNPs, during which the extract’s phytochemicals acted as reducing and stabilizing agents. FTIR, SEM/EDX, and VSM analyses confirmed successful surface modification and nanoparticle incorporation. The sequential treatments produced measurable add-on values (16.7% after amidoximation, followed by 10.9% and 8.5% after Fe₃O₄ and AgNP deposition, respectively). The Ag/Fe₃O₄-coated fabrics exhibited enhanced hydrophobicity and strong antimicrobial activity, with inhibition zones up to 14 mm against bacteria (including MRSA) and 26.9 mm against fungi at the highest Ag loading. Antioxidant activity was also markedly improved, showing up to a 78-fold increase in reducing power. Overall, this sustainable plant-mediated route provides an effective strategy for developing antimicrobial and antioxidant acrylic textiles for technical and protective applications. Full article

Light and antioxidant systems play a crucial role in the life activities of algal cells. This study investigates the algicidal efficacy of hydrogen peroxide (H₂O₂) against the harmful algal bloom (HAB)-forming dinoflagellate Prorocentrum donghaiense Lu, with a focus on the modulating roles of light conditions and iron ion environments. Within 180 min, dark-adapted cells showed 78% greater viability loss than light-exposed ones, and Fe₃O₄ nanoparticles synergistically enhanced H₂O₂ inhibition. Imaging and cytometry confirmed cell damage, including membrane rupture. Mechanistically, H₂O₂ penetrated cells, induced severe oxidative stress, suppressed photosynthesis, and compromised membrane integrity. Darkness likely exacerbated toxicity by depleting antioxidant reserves. This study elucidates an apoptosis-like pathway underlying H₂O₂-induced cell death and highlights the critical influence of ambient light on treatment efficiency. These findings reveal an apoptosis-like death pathway and highlight ambient light’s critical role, suggesting that optimized nighttime H₂O₂ application with nanomaterial synergists could improve HAB control strategies. Full article

The degradation of mercapto organic contaminants is highly important for safety and environmental protection since the specific chemical properties and the strong nature of S-containing bonds can make them less susceptible to traditional degradation mechanisms compared to other types of organic bonds. Thus, degradation of mercapto organic contaminants often requires catalysts with specific bandgap properties to ensure efficient generation of reactive species and appropriate redox potential alignment. Hence, in this work, we prepared bandgap-engineered semiconductor photocatalysts based on nanoparticles of different silica-doped spinel cobalt ferrite [SiO₂/CoFe₂O₄] (abbreviated as SiMCoF) [SiMCoF-1, SiMCoF-2, and SiMCoF-3] and characterized them by different analytical techniques. Since the dopant composition in a heterogeneous semiconductor material has important effects on its photocatalytic efficiency because adjusting the dopant profile can modulate impurity bands and enhance optical properties, which is crucial for the oxidative degradation of organic pollutants. Results from TEM, SEM, and their EDS analysis revealed that increased SiO₂ content showed improved surface area in the matrix, facilitating the increased absorption of oxygen impurities. This is further observed by the higher R_max values presented in AFM of SiMCoF-3 (139 nm) compared to SiMCoF-2 (116 nm) and SiMCoF-1 (8.78 nm), depicting its larger effective surface area (100 µm²), which in turn increases the active binding sites in the matrix. The Raman spectrum and XRD pattern of SiMCoF-3 showed various crystal planes with different atomic arrangements and a smaller crystallite size, leading to varying affinities for oxygen impurities. As a result, the optical bandgap decreased from 3.42 eV to 2.89 eV for SiMCoF-3, which is attributed to the quantum confinement effects caused by the smaller particle size and the dispersion of silica particles in the cobalt ferrite matrix. Thus, SiMCoF-3 showed elevated degradation performance without using any potential oxidants over the degradation of mercapto organic contaminants such as 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, and thiophenol under sunlight irradiation compared to other ferrites, and showed better results than Fenton’s reagent. Full article

The widespread use of antibiotics has taken a heavy toll on the environment, which cannot be ignored. Tetracycline antibiotics (TCs), as representative pharmaceutical contaminants, have emerged as a growing environmental concern due to their persistence and potential ecological risks. This study utilized 1,3,5-benzenetricarboxylic acid (BTC) as a functionalizing reagent to synthesize magnetic nanoparticles NiFe₂O₄-COOH. These were then combined with Zr-MOF to create the magnetic adsorbent designated as NCF@Zr-MOF (where NCF represents carboxyl-functionalized nickel ferrite). Magnetic solid-phase extraction (MSPE) technology was employed to remove two representative tetracycline antibiotics, tetracycline (TC) and chlortetracycline (CTC) from the environment. The Langmuir model fitting revealed maximum adsorption reached 190.85 and 196.32 mg/g for TC and CTC, respectively, both of which conformed to the pseudo-second-order model during the adsorption process with spontaneous, heat-absorbing and entropy-increasing properties. Furthermore, following five cycles of adsorption and desorption, the removal rate for TCs was found to have decreased by 30%, yet the removal of CTCs remained at 95.32%. This adsorbent enables rapid separation via an external magnetic field. With its excellent stability and reusability, NCF@Zr-MOF shows great potential for removing antibiotics from water. Full article

Inorganic arsenic species, As(V) and As(III), present significant toxicity and carcinogenic risks in water, making their effective removal critical for global water safety. This study introduces Fe-Ti-Mn/chitosan composite xerogel beads (FTMO/chitosan) designed to overcome the limitations of conventional single-component adsorbents, particularly for simultaneous removal of As(V) and As(III), and to address solid–liquid separation challenges common with powdered adsorbents. The xerogel beads feature a rough, porous surface composed of agglomerated nanoparticles. Batch tests demonstrated that the Freundlich model provided a better fit for the adsorption process, with max uptake capacities of 22.6 mg/g and 16.2 mg/g for As(III) and As(V) at 25 °C, respectively, outperforming most reported adsorbents. Adsorption kinetics were fast, reaching equilibrium within 24 h and fitting well with a pseudo-second-order kinetic model. The adsorption efficiency was strongly influenced by solution pH and the existence of minor coexisting anions. Mechanistically, As(V) removal occurred via inner-sphere surface complexation through the substitution of surface hydroxyl groups, whereas As(III) removal involved a coupled oxidation-adsorption process: MnO₂ oxidized As(III) to As(V), which was then adsorbed onto the material surface. Furthermore, the adsorbent confirmed excellent regeneration capacity and operational stability, illuminating its promising potential for frequent utilization in water treatment and environmental remediation applications. Full article

The dimensions and the reduction capacity of Fe₃O₄ nanoparticles are considered to be the key parameters in achieving the successful, efficient removal of hexavalent chromium, aiming for drinking water purification. This research study focuses on the optimization of reaction parameters during the oxidative precipitation of FeSO₄ carried out in a microwave-heated plug-flow reactor, to realize the preparation of Fe₃O₄ nanoparticles with an increased reduction potential as reflected in the Fe²⁺/Fe³⁺ ratio by approximating the ideal value of 0.5. In particular, the coupling of synthesis with features that allow for control of the oxidation extent, and include the addition of a reducing agent, an increase in ageing temperature, and inhibition of aggregation, were tested as potential approaches to tune the reducing potential and overcome reported Cr(VI) capture efficiencies provided by Fe₃O₄ nanoparticles. The evaluation results showed that adding a reductant after nanoparticle formation inhibits spontaneoussurface oxidation, bringing an improvement in the Cr(VI) uptake capacity for a residual concentration equal to the new EU regulation limit, by around 40%, reaching a value of 2.15 mg/g. However, working at an ageing temperature of around 100 °C resulted in an even better performance with an uptake increase of 120% and a capacity value of 3.45 mg/g. Finally, adding nanoparticles in the form of a dispersion instead of a dried powder provides an extra 10% improvement as a consequence of limited aggregation. Full article

In this study, we aimed to develop a high-performance, anti-fouling ultrafiltration membrane by integrating photocatalytic and Fenton-like functions into a polymer matrix, in order to address the critical challenge of membrane fouling and achieve simultaneous separation and degradation of organic pollutants. To this end, a novel Fe-V_O-TiO₂-embedded polyethersulfone (PES) composite membrane was designed and fabricated using a facile phase inversion method. The key innovation lies in the incorporation of Fe-V_O-TiO₂ nanoparticles containing abundant bulk-phase single-electron-trapped oxygen vacancies, which not only modulate membrane morphology and hydrophilicity but also enable sustained generation of reactive oxygen species for the pollutant degradation under light irradiation and H₂O₂. The optimized Fe-V_O-TiO₂-PES-0.04 membrane exhibited a significantly enhanced pure water flux of 222.6 L·m⁻²·h⁻¹ (2.2 times higher than the pure PES membrane) while maintaining a high bovine serum albumin (BSA) retention of 93% and an improved hydrophilic surface. More importantly, the membrane demonstrated efficient and stable synergistic Photocatalytic-Fenton activity, achieving 82% degradation of norfloxacin (NOR) and retaining 75% efficiency after eight consecutive cycles. A key finding is the membrane’s Photocatalytic-Fenton-assisted self-cleaning capability, with an 80% flux recovery after methylene blue (MB) fouling, which was attributed to in situ reactive oxygen species (·OH) generation (verified by ESR). This work provides a feasible strategy for designing multifunctional membranes with enhanced antifouling performance and extended service life through built-in catalytic self-cleaning. Full article

Introduction: Magnetic nanoparticles are widely investigated as multifunctional platforms for drug delivery and theranostic applications, yet their biomedical implementation is hindered by aggregation, limited colloidal stability, and insufficient biocompatibility. Hybrid biopolymer coatings can mitigate these issues while supporting drug incorporation. Aim: This study aimed to develop casein–pullulan-coated Fe₃O₄ nanocomposites loaded with xanthohumol, enhancing stability and enabling controlled release for potential theranostic use. Methods: Fe₃O₄ nanoparticles were synthesized through co-precipitation and incorporated into a casein–pullulan matrix formed via polymer complexation and glutaraldehyde crosslinking. A 3² full factorial design evaluated the influence of casein:pullulan ratio and crosslinker concentration on physicochemical performance. Nanocomposites were characterized for size, zeta potential, morphology, composition, and stability, while drug loading, encapsulation efficiency, and release profiles were determined spectrophotometrically. Molecular docking was performed to examine casein–pullulan interactions. Results: Uncoated Fe₃O₄ nanoparticles aggregated extensively, displaying mean sizes of ~292 nm, zeta potential of +80.95 mV and high polydispersity (PDI above 0.2). Incorporation into the biopolymer matrix improved colloidal stability, yielding particles of ~185 nm with zeta potentials near –35 mV. TEM and SEM confirmed spherical morphology and uniform magnetic core incorporation. The optimal formulation, consisting of a 1:1 casein:pullulan ratio with 1% glutaraldehyde, achieved 5.7% drug loading, 68% encapsulation efficiency, and sustained release of xanthohumol up to 84% over 120 h, fitting Fickian diffusion (Korsmeyer–Peppas R² = 0.9877, n = 0.43). Conclusions: Casein–pullulan hybrid coatings significantly enhance Fe₃O₄ nanoparticle stability and enable controlled release of xanthohumol, presenting a promising platform for future targeted drug delivery and theranostic applications. Full article

Shallot (Allium hirtifolium Boiss.) is of considerable nutritional and medical significance due to its strong antioxidant properties; however, no nanophytotoxicity studies have assessed whether the use of nanofertilizers would improve shallot performance, micronutrient iron (Fe) enrichment, and yield in semi-arid regions. Herein, we evaluated the effects of magnetite nanoparticles (nFe₃O₄) on shallot grown for a full lifecycle in two semi-arid regions through bulb-priming followed by foliar application and compared them with conventional ferrous sulfate (FeSO₄) fertilizer and untreated control. Our results showed remarkable cellular adaptations to semi-arid climate upon nFe₃O₄ treatment as leaves displayed thickened cell walls, distinct chloroplasts featuring organized thylakoid grana and stroma, normal mitochondria, abundant starch grains, and plastoglobuli around chloroplasts compared to FeSO₄ or untreated control. At 900 mg/L nFe₃O₄, chlorophyll-a, chlorophyll-b, and carotenoid increased by 27–55%, 108–126%, and 77–97%, respectively, compared to FeSO₄ applied at recommended field rate (1800 mg/L). Significant increments in bulb diameter (38–39%) and sister bulb number (300–500%) were observed upon 900 mg/L nFe₃O₄ treatment compared to FeSO₄ (1800 mg/L) and control. Furthermore, with 900 mg/L nFe₃O₄ treatment, total phenol, flavonoids, and Fe in bulbs increased by 27–46%, 29–73%, and 486–549%, respectively, compared to FeSO₄ (1800 mg/L). These findings demonstrate that bulb-priming followed by foliar application of 900 mg/L of nFe₃O₄ could significantly promote cellular adaptation, thereby improving photosynthetic efficiency, bulb yield, antioxidant activities, and Fe biofortification in shallot, and may serve as a novel approach for improving shallot production in semi-arid regions. Full article

This work investigates the feasibility of synthesis hybrid x Gd₂O₃ + (100 − x) Fe₃O₄ nanoparticles using the scalable method of high-energy ball milling for dual-contrast magnetic resonance imaging applications. Comprehensive studies of the structure, magnetic and functional properties of the hybrid nanoparticles were conducted. It was found that the milling process initiates the transformation of the cubic phase c-Gd₂O₃ ($\mathrm{I}\mathrm{a}\overline{3}$) into the monoclinic m-Gd₂O₃ (C2/m). Measurements of the magnetic properties showed that the specific saturation magnetization of the Fe₃O₄ phase is substantially reduced, which is a characteristic feature of nanoparticles due to phenomena such as surface spin disorder and spin-canting effects. The transmission electron microscopy results confirm the formation of hybrid Fe₃O₄-Gd₂O₃ nanostructures and the measured particle sizes show good correlation with the X-ray diffraction results. A comprehensive structure–property relationship study revealed that the obtained hybrid nanoparticles exhibit high r₂ values, reaching 160 mM⁻¹s⁻¹ and low r₁ values, a characteristic that is determined primarily by the presence of a large fraction of Gd₂O₃ particles with sizes of ≈30 nm and Fe₃O₄ crystallites of ≈10 nm. Full article

The increasing energy crisis demands sustainable functional materials. Wood, with its natural three-dimensional porous structure, offers an ideal renewable template. This study demonstrates that microstructural engineering of wood is a decisive strategy for enhancing magnetothermal conversion. Using eucalyptus wood, we precisely tailored its pore architecture via delignification and synthesized Fe₃O₄ nanoparticles in situ through coprecipitation. We systematically investigated the effects of delignification and precursor immersion time (24, 48, 72 h) on the loading, distribution, and magnetothermal performance of the composites. Delignification drastically increased wood porosity, raising the Fe₃O₄ loading capacity from ~5–6% (in non-delignified wood) to over 14%. Immersion time critically influenced nanoparticle distribution: 48 h achieved optimal deep penetration and uniformity, whereas extended time (72 h) induced minor local agglomeration. The optimized composite (MDW-48) achieved an equilibrium temperature of 51.2 °C under a low alternating magnetic field (0.06 mT, 35 kHz), corresponding to a temperature rise (ΔT) > 24 °C and a Specific Loss Power (SLP) of 1.31W·g⁻¹. This performance surpasses that of the 24 h sample (47 °C, SLP = 1.16 W·g⁻¹) and rivals other bio-based magnetic systems. This work establishes a clear microstructure–property relationship: delignification enables high loading, while controlled impregnation tunes distribution uniformity, both directly governing magnetothermal efficiency. Our findings highlight delignified magnetic wood as a robust, sustainable platform for efficient low-field magnetothermal conversion, with promising potential in low-carbon thermal management. Full article

Direct hydroxylation of benzene to phenol using hydrogen peroxide is a cornerstone of sustainable green chemistry. This paper presents the results of a stability study of an iron-containing mordenite catalyst in the liquid-phase hydroxylation of benzene to phenol with a 30% aqueous hydrogen peroxide solution. The study utilizes a combination of catalytic activity measurements, dynamic light scattering (DLS), and electron paramagnetic resonance (EPR) spectra. The system is initially shown to exhibit high phenol selectivity; however, over time, DLS measurements indicate aggregation of the catalyst particles with an increase in the average particle diameter from 1.8 to 2.6 μm and the formation of byproducts–dihydroxybenzenes. Iron is present predominantly as magnetite nanoparticles (Fe₃O₄) ~10 nm in diameter, stabilized on the outer surface of mordenite, with minor leaching (<10%) due to the formation of iron ion complexes with ascorbic acid as a result of the latter’s interaction with magnetite particles. Using a thermodynamic approach based on the Ulich formalism (first and second approximations), it is shown that the reaction of benzene hydroxylation H₂O₂ in the liquid phase is thermodynamically quite favorable (ΔG° = −(289–292) kJ·mol⁻¹ in the range of 293–343 K, K = 1044–1052). It is shown that ascorbic acid acts as a redox mediator (reducing Fe³⁺ to Fe²⁺) and a regulator of the catalytic medium activity. The stability of the catalytic system is examined in terms of the Lyapunov criterion: it is shown that the total Gibbs free energy (including the surface contribution) can be considered as a Lyapunov functional describing the evolution of the system toward a steady state. Ultrasonic (US) treatment of the catalytic system is shown to redisperse aggregated particles and restore its activity. It is established that the catalytic activity is due to nanosized Fe₃O₄ particles, which react with H₂O₂ to form hydroxyl radicals responsible for the selective hydroxylation of benzene to phenol. Full article