Iron Oxide Research Articles

Magnetite Reduced Graphene Oxide/Ordered Mesoporous Carbon Nanocomposite as Effective Adsorbent for Removal of 2-Naphthol in Wastewater

Background: The wastewater released from various industries contains substantial amounts of organic compounds such as dyes and naphthols. However, naphthols are toxic to the environment and human health. So, it is essential to eliminate them, which will contribute to manufacturing and environmental management. Methods: In the work, an eco-friendly method is adapted to synthesize reduced graphene oxide (rGO) using Equisetum arvense plant extract as a strong reducing and stabilizing agent. Then, a hybrid nano adsorbent based on rGO and ordered mesoporous carbon (CMK-3) decorated with iron oxide nanoparticles (Fe3O4@rGO/CMK-3) was prepared as an adsorbent. We investigate the performance of Fe3O4@rGO/CMK-3 to remove 2-naphthol (2-NP). Results: The FE-SEM images exhibited spherical magnetite nanoparticles with sizes ranging from 31 to 47 nm on composite. Efficient removal (90%) of 2-NP from aqueous solution is demonstrated using high surface area Fe3O4@rGO/CMK-3 (initial concentration of 2-NP: 10 mg mL-1, pH: 5.0, time: 30 min, and amount of adsorbent dosage: 3 mg mL-1). The high surface area of Fe3O4@rGO/CMK-3, hydrogen binding, π-π stacking interaction between the benzene rings of 2-NP and graphitic skeleton of hybrid adsorbent facilitate the adsorption of 2-NP on the Fe3O4@rGO/CMK-3. The 2NP removal capacity by (Fe3O4@rGO/CMK-3) showed a significant decrease during five successive cycles. Conclusions: These results promise the potential of high surface area (Fe3O4@rGO/CMK-3) for efficient removal of 2-NP for wastewater treatment.

Hematite enhances microbial autotrophic nitrate removal in carbonate and phosphate-rich environments by increasing Fe(II) activity

Groundwater contamination by nitrates presents significant risks to both human health and the environment. In groundwater characterized as oligotrophic—low in organic carbon, but abundant in carbonate and phosphate—chemolithoautotrophic bacteria, including nitrate-reducing Fe(II)-oxidizing bacteria (NRFeOB), play a vital role in denitrification. The chemoautotrophic nitrate reduction is sensitive to environmental factors, including widespread iron oxides like hematite in nature. However, the specific mechanisms of this influence remain unclear. We examined the mechanism of how hematite impacts autotrophic nitrate reduction in a model NRFeOB community known as culture KS. We found that hematite enhances the rate of autotrophic nitrate reduction by promoting Fe(II) oxidation. Mössbauer spectroscopy detected a significant amount of adsorbed Fe(II) when hematite was present, leading to a reduction in dissolved ferrous iron. In conjunction with XRD data, it can be inferred that the formation of vivianite decreased, thereby increasing the Fe(II) activity in the reaction system. Within the culture KS bacterial consortium, hematite fosters the proliferation of autotrophic microorganisms, specifically Gallionellaceae, and amplifies the presence of denitrifying microbes, notably Rhodanobacter. This dual enhancement improves Fe(II) utilization and nitrate reduction capabilities. Our findings highlight intricate interactions between hematite and a model NRFeOB community, offering insights into groundwater nitrate removal mechanisms and the ecological strategies of autotrophic bacteria in mineral-rich environments.

El láser en la restauración de hierros arqueológicos intensamente mineralizados: criterios y protocolo de intervención en el caso de las armas de una necrópolis Vaccea (Valladolid, España)

The aim of this paper is to present the conservation treatment of a set of iron weapons from the Vaccean necropolis of the Ruedas de Pintia (Padilla de Duero, Valladolid) dated between the 4th century BCE and 2nd century CE. The cremation and burial conditions have been very detrimental to their state of conservation, generating an intense corrosion and their complete mineralization. This left the weapons in a very fragile and brittle state that made their restoration difficult, since it implied the removal of hard crusts that were much adhered to the surface and, during this process, the pieces were in danger of further fragmentation. Our proposal is the combined use of traditional abrasive cleaning techniques together with the 1064nm Nd:YAG laser cleaning that, in addition to removing corrosion products, transforms the surface into magnetite, a stable iron oxide.

Modulation of Solid-state Thermal Reaction of Iron(III)Citrate by a Co-precursor Studied using Thermogravimetry: Evaluation of Kinetic and Thermodynamic Parameters and Nucleation Rate

Background: Solid state reaction of iron(III)citrate leads to a range of ironbased oxides by varying the reaction conditions, e.g., the presence of co-precursor. The influence of reaction conditions on the kinetics of the solid-state reaction of iron(III)citrate needs to be investigated. Objective: Kinetic analysis of the solid-state reaction of iron(III)citrate in the presence of a co-precursor has been explored to realize the influences of the co-precursor on the reaction process as well as decomposed material. Method:: Non-isothermal thermogravimetry profiles are deconvoluted to individual reaction steps. The model-free kinetic methodology is utilized to estimate step-wise activation energy and, hence, the reaction mechanism along with the reaction rate. Conversiondependent thermodynamic parameters and nucleation rate are estimated. XRD analysis has been used to characterize the decomposed material. Results: Thermogravimetry profiles obtained for an iron(III)citrate and malonic acid mixture are deconvoluted into six steps. The decomposed nanomaterial is identified as magnetite (size 10 nm). The observed reaction mechanisms associated with each step are different, where the activation/reaction rate is conversion-dependent. A good fit between the experimental and reverse-constructed conversion profiles is obtained. The nucleation rate at higher temperatures is affected by both the extent of conversion and the heating rate. A possible reaction pathway is proposed. The study elucidates the role of malonic acid as a co-precursor in modifying the thermal reaction of iron(III)citrate and product formation. Conclusion: This investigation proposes the applicability of suitable co-precursors as a potential controlling factor for preparing iron oxides from iron-based compounds.

Competitive adsorption behavior of As(V) and Sb(V) on Hematite: Facet and pH dependent coordination affinity and role of outer-sphere complexes

The environmental mobility and fate of arsenic (As) and antimony (Sb) are influenced by ubiquitous iron minerals, but little is known about whether their co-adsorption behavior is affected by the exposed facets. Herein, we used cubic and rod-shaped hematite nanocrystals (HNC and HNR) to investigate the effect of exposed facets on competitive adsorption behaviors. TEM analysis indicated that the primary exposed facets of HNC and HNR were {110} and {012}, separately. Calculations supported the predictions of our model, revealing that the competition in acidic and alkaline environments was mainly influenced by the affinity and bond stability of facet-related adsorption configurations. However, the competition in neutral conditions was jointly influenced by facet-related coordination and adsorption behavior, due to the dependence of Sb(V) on protonation sites. On HNR (pH = 3), the adsorption of Sb(V) (50.6 %) was approximately twice that of As(V) (27.8 %) for its significant advantage in bidentate coordination on the {110} facet, whereas on HNC, As(V) (65.9 %) and Sb(V) (69.3 %) exhibited similar competitiveness. Notably, As(V) and Sb(V) tend to be adsorbed through outer-sphere coordination under alkaline conditions. On the {012} facet, As(V) and Sb(V) exhibited similar competitiveness for outer-sphere sites, whereas on the {110} facet, As(V) outer-sphere coordination showed stronger affinity, giving it an edge in competing on HNR. Overall, this study elucidated the critical role of varying exposed facets in the competitive adsorption process and proposed novel strategies for the selective removal of coexisting As(V) and Sb(V) through tailored fixed-facet iron oxides.

Rhodium-doped iron oxides promoted by sodium for highly selective hydrogenation of CO2 to ethanol and C2+ hydrocarbons

Hydrogenation of CO2 to produce high-value C2 + products has gained great interest, but catalyst design for highly selective ethanol still remains a challenge. Herein, bifunctional catalysts of iron oxide promoted with rhodium and sodium, Na-Rh-FeOx and Rh-FeOx-Na, were prepared by using simple methods of incipient wetness impregnation (IWI) and coprecipitation. The former catalyst prepared via IWI, Na-Rh-FeOx, is remarkably efficient for the hydrogenation of CO2 to ethanol with high selectivity of 91 % at 200 °C in the liquid fraction. The latter catalyst synthesized solely through the coprecipitation in a sodium-containing medium, Rh-FeOx-Na, displayed the synergy effect to perform a better CO2 conversion of 23 % at 200 °C. Characterization of catalysts via XRD, XPS, N2 physisorption, CO2-TPD, and gas pulse-chemisorption reveals that different preparation methods influenced the dispersion of sodium particles. This property, in turn, impacts the ratio of hydrogen-activating sites to CO-adsorption sites, directly related to the balance between dissociative- and non-dissociative CO* intermediates, which is crucial for ethanol formation. Adding alkali metal facilitates the formation of iron carbide Fe5C2, known to be active for C–C propagation. Integrating Na-Rh-FeOx with ZSM-5 support further increased ethanol selectivity up to 97 % in liquid phase and 90 % in gas phase. By selecting a proper route for introducing alkali metals and combining with supports, the catalyst properties can be effectively tailored, thereby regulating the catalytic activity and selectivity.

Magnetic-Responsive Triple Shape Memory Polymer from Bio-Based Benzoxazine/Urethane Polymer Alloys with Iron Oxide Nanoparticles

Novel magnetic-responsive triple shape memory polymers (SMPs) derived from bio-based benzoxazine-urethane (V-fa/PU) polymer alloys containing iron oxide nanoparticles (Fe3O4 NPs) were developed in this work. Shape memory effect and curing behavior of the alloys were investigated at various bio-based PU contents. The polymerization of V-fa/PU polymer alloys with a heterogeneous network generated a broad glass transition temperature, which is a crucial feature for the development of triple SMPs. The influence of Fe3O4 NPs incorporation into the polymer nanocomposites on the SMP performance triggered by magnetic fields was also investigated. It was found that the addition of Fe3O4 NPs can enhance the dynamic mechanical properties and magnetic characteristics of the V-fa/PU polymer alloys thanks to the superparamagnetic property of Fe3O4 NPs. Moreover, the performance of the SMPs based on V-fa/PU polymer nanocomposites filled with Fe3O4 NPs showed high shape fixity of up to 98%, a shape recovery of 98%, and a recovering time of 8 s. Furthermore, bio-based V-fa/PU polymer alloys containing Fe3O4 NPs were developed as magnetic responsive triple SMPs with shape fixity in the range of 95–97% and shape recovery in the range of 85–95%. The results suggested that magnetic responsive triple SMPs from bio-based V-fa/PU polymer alloys filled with Fe3O4 NPs are promising candidate for advanced applications.

Activation of Persulphate by a Waste-Extracted Metal–Organic Framework-Derived Iron Oxide as a Photocatalyst for Effective Degradation of Salicylic Acid

Activation of Persulphate by a Waste-Extracted Metal–Organic Framework-Derived Iron Oxide as a Photocatalyst for Effective Degradation of Salicylic Acid

Skin Staining After Injection of Superparamagnetic Iron Oxide for Sentinel Lymph Node Dissection: A Retrospective Study of Two Protocols for Injection and Long-Term Follow-Up

Skin Staining After Injection of Superparamagnetic Iron Oxide for Sentinel Lymph Node Dissection: A Retrospective Study of Two Protocols for Injection and Long-Term Follow-Up

Comparative analysis of microstructural, compositional, and grazing incidence characteristics of oxide scale on 316L steel: SLM vs. wrought conditions

The aim of this research is to compare the oxidation behavior and characteristics of oxide scale of 316L steel produced by two methods: selective laser melting (SLM) and conventional casting and forming (wrought). To this end, the initial composition and microstructure of samples produced by those methods were first studied. Thermogravimetric analysis (TGA) and long-term isothermal oxidation tests were carried out on the samples and the oxidation kinetics were compared. The oxidized samples were then examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and grazing incidence X-ray diffraction (GIXRD). The results indicated that in the temperature range of 600 °C–900 °C, the oxidation resistance of the SLM alloy is lower than that of the wrought alloy, especially at 800 °C. This is attributed to the combined effect of: i) smaller grain size due to the rapid solidification in the SLM alloy that increases the paths of oxygen penetration, ii) lower presence of chromium and manganese elements in the oxide layer and iii) preferential growth of iron oxide in the form of hillocks on the surface. Surface and cross-section analysis of the oxide layers show that iron oxide is dominant on the surface of the SLM sample at temperatures of 600 °C and 800 °C, and at 800 °C its extended hilly growth leads to significant spallation of the oxide scale and an exponential increase in the oxidation rate. However, at 900 °C, with the formation of a continuous oxide layer containing Fe2MnO4 and CrMnO4, the oxidation rate significantly decreases in both alloys.

PHYSICOCHIMICAL,MINERALOGICALAND GEOTECHNICALCHARACTERIZATION OF THE EARTH OF THE 9TH DISTRICT OF THE CITY OF NDJAMENA IN CHAD WITH A VIEW TO THE CONSTRUCTION OF HYDRAULIC STRUCTURES

The work carried out in this paper aims at the physicochimical, mineralogical and geotechnical characterization of the soils used in the construction of dikes in the 9th district of the city of NDjamena in Chad in order to guide those responsible for the construction of structures related to this soil.Physicochimical,mineralogical and geotechnical analyses were conducted. The results obtained show that the soils used for the construction of the dikes (existing structure is a dam made of earth without a coating at the time) are fine soils with a percentage of the fines that varies between 38.7% and 73.1% at the 80μm screen. According to the GTR classification, these floors belong to classes A2 and A3.The plasticity index of the soils studied ranges from 18 to 35. These values confirm that the soils used are plastic soils. The porosity is in the range of 34.23% to 40% and the void index is between 0.36 and 0.59. These soils are very sensitive to water, compaction and deformation.Chemical analysis shows us that Silicon oxide is the most dominant constituent (63.29% to 80.22%) followed by Aluminum oxide (10.49% to 18.15%) and iron oxide (3.22% to 5.87%).Mineralogical analysis confirms that Quartz is dominant (56.24% to 46.5%) followed by Kaolinite (27.41% to 12.07%), illite (12.38% to 9.43%), k-feldspar, plagioclase and other minerals. The presence of smectite shows that the soils are made up of clays that have a high swelling capacity. Thus, the use of these soils in hydraulic structures such as dikes and dams requires special treatment so that it can effectively perform their roles.

Interfacial effects of Cu/Fe3O4 in water-gas shift reaction: Role of Fe3O4 crystallite sizes

Copper-promoted iron oxides are commonly utilized in high-temperature water-gas shift (WGS) reactions. Although the promotional effect of Cu has been previously documented, the nature of the active sites for Cu/Fe3O4 remains debated and the role of the crystallite size of Fe3O4 has not been tackled. In this study, a wide range of Cu/Fe3O4 catalysts were designed by hosting Cu species onto Fe3O4 of two contrasting crystallite sizes (approximately 10 and 160 nm) and by utilizing different preparation methods (ammonia evaporation and deposition-precipitation). The evaluation of their catalytic WGS performances revealed a remarkable and previously undocumented phenomenon: the addition of Cu resulted in universal activity enhancements only for small Fe3O4 crystals, while the larger analogues displayed decreased activity. This peculiar phenomenon can be explained by the creation of Cu–Fe3O4 interfaces present in the iron oxides of small crystallite sizes. Thorough characterizations, such as advanced electron microscopic, in situ powder X-ray diffractions, in situ diffuse reflectance infrared Fourier transform spectroscopy, and computational studies, suggest strong electronic interactions between the different metal species, facilitated reductions of the individual oxides, and more favorable CO activation at the interfacial sites, all accounting for the promoted activity.

SPECIATION OF HEAVY METALS AND MICROBIAL CONTAMINANTS IN HARMATTAN DUST WITHIN THE FEDERAL POLYTECHNIC KAURA NAMODA MAIN CAMPUS, ZAMFARA STATE

Harmattan dust is a natural phenomenon contributing to air pollution due to the presence of heavy metals and microorganisms. This research aimed to determine the speciation of heavy metal and microbial contaminants in Harmattan dust samples within the polytechnic Kaura Namoda. The composite sample of each month, namely, December 2023, January 2024, and February 2024, was collected with the aid of a sterilized petri dish. Five extraction phases were carried out, in order of mobility of the metals: exchangeable ion > metal bound with carbonate > metal bound to iron and manganese oxide > metals bound to organic matter and sulfide > residual phase. This was achieved using Tessie’s method and AAS for extraction and analysis. The result for the heavy metals shows Cr (13.6%) and Zn (25.5%) are more abundant in the exchangeable phases in December and January. Metals bound to Fe and MnO extraction phases have Zn (25.50%) abundance in December and January. The residual phase of extraction shows the highest percentage of pb (95.3%) and nickel (85.40%) for December and January. The bacteria and fungi identified are Bacillus cereus, Staphylococcus, Aspergillum, and Clodosporium, respectively. There is no significant difference in physicochemical parameters between the Harmattan dust samples collected in December, January, and February. The percentages of heavy metals in the Harmattan dust are high in the immobility phase of extraction, and bacterial and fungal levels are high in December and January. There is a need for preventive and protective measures to mitigate the health effects associated with...

Biosynthesis of Iron Oxide Nanoparticles and Combination with Glyphosate Herbicide and Effect Against Cogon Grass Control

For enhancing herbicide efficacy a total of 42 soil samples, five species of bacteria that grew the most were selected for regarding other isolates: (Enterobacter cloacae, Serratia fonticola, Aeromonas hydrophila, Pantoea spp., Pseudomonas mendocina). Extracellular extracts of these bacteria were made and then used to manufacture iron oxide nanoparticles biologically. It was observed after measuring the average diameter by AFM (Atomic Force Microscopy) for each NPs prepared were 65.14, 29.21, 63.87, 57.89 and 36.59 nm, respectively. The synthesis conditions were a pH of 7 and 50°C. Based on the AFM values, Serratia fonticola was selected as having the smallest average diameter of 29.21 nm to complete the rest of the techniques (UV-VIS, AFM, FTIR and FE-SEM). The wavelength of Fe2O3NPs by using UV-VIS is 359 nm, Image FE-SEM displays spherical Fe2O3NPs in Nano-cluster form and the average volume is 29.21 nm by AFM. Utilizing the Randomized Complete Block Design methodology with 6 treatments, two factors: Glyphosate herbicide at the recommended dose and three concentrations of the prepared (Fe2O3NPs) from Serratia fonticola were 0.5, 1 and 1.5 g/ml. Halfa plant was controlled using these treatments, and after 30 days, the efficiency of the treatments was measured on a set of characteristics. It was found the lowest number of plants and the highest percentage of control was in the treatment 5 glyphosate and Fe2O3 NPs con. (1.5g/ml) was 1.26, 5.33 and 90%, respectively. The study effectively shows the potential of employing Fe2O3NPs generated from S. fonticola to improve the efficacy of Glyphosate for Cogon management.

Biogenic Iron Oxide Nanoparticles Based on Algal Biofilm Formed in the Wastewater Treatment Plant and Their Dye Removal Performance

In the field of environmental pollution removal, bioremediation plays a crucial role in removing or converting toxic substances from the environment. Bacteria, yeasts, molds, algae, and plants are widely used in bioremediation events. Recently, green-synthesized nanoparticles have also been employed in bioremediation applications. In this study, iron oxide nanoparticles (FeONPs) were synthesized from algal biofilms that are naturally formed in the settling ponds of the Gümüşhane Municipality Wastewater Treatment Plant. These biological nanoparticles were utilized to investigate their adsorption efficiency for water-polluting dyes such as methylene blue (MB), malachite green (MG), and phenol red (PR). The synthesized FeONPs were characterized using Fourier transform infrared spectroscopy (FTIR) scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD). To test their efficacy, MB, MG, and PR dye solutions were treated with 5.0, 10.0, and 20 g/L FeONP concentrations. The remaining dye concentrations were quantified with a UV-VIS spectrophotometer after filtration. The results showed that FeONPs obtained from algal biofilms effectively removed MB, MG, and PR, with the highest efficiency observed for PR.

Cu1−Fe Dual Sites for Superior Neutral Ammonia Electrosynthesis from Nitrate

AbstractThe electrochemical nitrate reduction reaction (NO3RR) is able to convert nitrate (NO3−) into reusable ammonia (NH3), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO3− to NH3 undergoes water dissociation to generate active hydrogen atoms and nitrogen‐containing intermediates hydrogenation tandemly. The two relay processes compete for the same active sites, especially under pH‐neutral condition, resulting in the suboptimal efficiency and selectivity in the electrosynthesis of NH3 from NO3−. Herein, we constructed a Cu1‐Fe dual‐site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero‐valent iron (nZVI) for the electrochemical NO3RR, achieving an impressive NO3− removal efficiency of 94.8 % and NH3 selectivity of 99.2 % under neutral pH and nitrate concentration of 50 mg L−1 NO3−−N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO3− adsorption on Fe sites and strengthened water activation on single‐atom Cu sites, decreasing the energy barrier for the rate‐determining step of *NO‐to‐*NOH. This work develops a novel strategy of fabricating dual‐site catalysts to enhance the electrosynthesis of NH3 from NO3−, and presents an environmentally sustainable approach for neutral nitrate wastewater treatment.

Adsorption Characteristics of Antibiotic Oxytetracycline on CoFe2O4@Au nanocomposite

Oxytetracycline (OTC) is a widely used broad-spectrum antibiotic for treating bacterial infections in humans and animals. Gold nanoparticles (AuNPs) and cobalt iron oxide (CFO) were combined to create composite magnetic materials designed for the selective adsorption of OTC. The strong affinity of AuNPs for the amine group in the OTC molecule allows for the preferential adsorption of OTC. Simultaneously, the high magnetism of CFO enables the efficient retrieval of materials from the sample solution. The CFO@Au nanomaterials showed an enhanced adsorption capacity of 23.75 mg/g at optimum conditions of pH 7.0; an adsorption time of 90 min, and an adsorbent mass of 0.05g. The adsorption isotherm was in accordance with a Langmuir monolayer model while the kinetic adsorption follows pseudo–second-order kinetic model.. This study provides a simple method for the effective adsorption of OTC as well as a suggestion for the adsorption of other amine-containing substances.

Cu1-Fe Dual Sites for Superior Neutral Ammonia Electrosynthesis from Nitrate.

The electrochemical nitrate reduction reaction (NO3RR) is able to convert nitrate (NO3 -) into reusable ammonia (NH3), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO3 - to NH3 undergoes water dissociation to generate active hydrogen atoms and nitrogen-containing intermediates hydrogenation tandemly. The two relay processes compete for the same active sites, especially under pH-neutral condition, resulting in the suboptimal efficiency and selectivity in the electrosynthesis of NH3 from NO3 -. Herein, we constructed a Cu1-Fe dual-site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero-valent iron (nZVI) for the electrochemical NO3RR, achieving an impressive NO3 - removal efficiency of 94.8 % and NH3 selectivity of 99.2 % under neutral pH and nitrate concentration of 50 mg L-1 NO3 --N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO3 - adsorption on Fe sites and strengthened water activation on single-atom Cu sites, decreasing the energy barrier for the rate-determining step of *NO-to-*NOH. This work develops a novel strategy of fabricating dual-site catalysts to enhance the electrosynthesis of NH3 from NO3 -, and presents an environmentally sustainable approach for neutral nitrate wastewater treatment.

Evolution of red ceramic pigments: from hazardous compounds to environmentally friendly alternatives

Synthesis of red ceramic pigments is a challenging task in the ceramic industry. Most classic reds are based on severely toxic materials including lead, arsenic, mercury, selenium, and cadmium, which are forbidden in many countries. On the other hand, the red color is super sensitive to the synthesis parameters, heat treatment conditions (atmosphere and temperature), particle size, etc. Therefore, achieving a bright true red shade and its stability at high temperatures is crucial. There has been a massive attempt to find a sustainable high-temperature resistant alternative for these hazardous compounds. Iron oxide is one of the first red pigments in history, but it cannot produce a bright red shade and its color is mostly red-brown. Ce2S3 is another red pigment with a beautiful red color. But it cannot stand the temperature above 350 °C in an oxidizing atmosphere. Doping lanthanides in the perovskites or entrapping the toxic beautiful chromophores in the core-shell structures are among the strategies to achieve safe bright red pigments. This review outlines the recent progress of hazardous classic reds to environmentally friendly ceramic red pigments. Various compounds and dopants, applied to develop sustainable reds, from simple iron-oxides to composites, solid solutions, core-shell structures, or even purified wastes have been covered in this review.

Biodegradation by Cancer Cells of Magnetite Nanoflowers with and without Encapsulation in PS-b-PAA Block Copolymer Micelles.

Magnetomicelles were produced by the self-assembly of magnetite iron oxide nanoflowers and the amphiphilic poly(styrene)-b-poly(acrylic acid) block copolymer to deliver a multifunctional theranostic agent. Their bioprocessing by cancer cells was investigated in a three-dimensional spheroid model over a 13-day period and compared with nonencapsulated magnetic nanoflowers. A degradation process was identified and monitored at various scales, exploiting different physicochemical fingerprints. At a collective level, measurements were conducted using magnetic, photothermal, and magnetic resonance imaging techniques. At the nanoscale, transmission electron microscopy was employed to identify the morphological integrity of the structures, and X-ray absorption spectroscopy was used to analyze the degradation at the crystalline phase and chemical levels. All of these measurements converge to demonstrate that the encapsulation of magnetic nanoparticles in micelles effectively mitigates their degradation compared to individual nonencapsulated magnetic nanoflowers. This protective effect consequently resulted in better maintenance of their therapeutic photothermal potential. The structural degradation of magnetomicelles occurred through the formation of an oxidized iron phase in ferritin from the magnetic nanoparticles, leaving behind empty spherical polymeric ghost shells. These results underscore the significance of encapsulation of iron oxides in micelles in preserving nanomaterial integrity and regulating degradation, even under challenging physicochemical conditions within cancer cells.