Green Synthesis of Fe3O4 Nanoparticles and Survey their Magnetic Properties

Green and sustainable synthesis of nanomaterials: Recent advancements and limitations

Nanomaterials have been widely used in diverse fields of research such as engineering, biomedical science, energy, and environment. At present, chemical and physical methods are the main methods for large-scale synthesis of nanomaterials, but these methods have adverse effects on the environment, and health issues, consume more energy, and are expensive. The green synthesis of nanoparticles is a promising and environmentally friendly approach to producing materials with unique properties. Natural reagents such as herbs, bacteria, fungi, and agricultural waste are used in the green synthesis of nanomaterials instead of hazardous chemicals and reduce the carbon footprint of the synthesis process. Green synthesis of nanomaterials is highly beneficial compared to traditional methods due to its low cost, negligible pollution level, and safety for the environment and human health. Nanoparticles possess enhanced thermal and electrical conductivity, catalytic activity, and biocompatibility, making them highly attractive for a range of applications, including catalysis, energy storage, optics, biological labeling, and cancer therapy. This review article provides a comprehensive overview of recent advancements in the green synthesis routes of different types of nanomaterials, including metal oxide-based, inert metal-based, carbon-based, and composite-based nanoparticles. Moreover, we discuss the various applications of nanoparticles, emphasizing their potential to revolutionize fields such as medicine, electronics energy, and the environment. The factors affecting the green synthesis of nanomaterials, and their limitations are also pointed out to decide the direction of this research field, Overall, this paper highlights the importance of green synthesis in promoting sustainable development in various industries.

Factors Affecting the Analytical Performance of Magnetic Molecularly Imprinted Polymers

During the last few years, separation techniques using molecular imprinting polymers (MIPs) have been developed, making certain improvements using magnetic properties. Compared to MIP, Magnetic molecularly imprinted polymers (MMIPs) have high selectivity in sample pre-treatment and allow for fast and easy isolation of the target analyte. Its magnetic properties and good extraction performance depend on the MMIP synthesis step, which consists of 4 steps, namely magnetite manufacture, magnetic coating using modified components, polymerization and template desorption. This review discusses the factors that will affect the performance of MMIP as a selective sorbent at each stage. MMIP, using Fe₃O₄ as a magnetite core, showed strong superparamagnetism; it was prepared using the co-precipitation method using FeCl₃·6H₂O and FeCl₂·H₂O to obtain high magnetic properties, using NH₄OH solution added for higher crystallinity. In magnetite synthesis, the use of a higher temperature and reaction time will result in a larger nanoparticle size and high magnetization saturation, while a higher pH value will result in a smaller particle size. In the modification step, the use of high amounts of oleic acid results in smaller nanoparticles; furthermore, determining the correct molar ratio between FeCl₃ and the shielding agent will also result in smaller particles. The next factor is that the proper ratio of functional monomer, cross-linker and solvent will improve printing efficiency. Thus, it will produce MMIP with high selectivity in sample pre-treatment.

Sustainable plant and microbes-mediated preparation of Fe3O4 nanoparticles and industrial application of its chitosan, starch, cellulose, and dextrin-based nanocomposites as catalysts

Iron oxide nanoparticles (Fe₃O₄ NPs) attracted significant scientific interest, considering their immense diversity of usage and biocompatibility. Perceiving the growing importance of sustainable chemistry, many efforts have been made to prepare these NPs using naturally occurring materials mostly plant extracts and microbes. Magnetic NPs (MNPs) are commonly used as composites and are considered in two matters: synthesis and modification of their functional groups. Biopolymeric nanocomposites are a group of hybrid materials composed of natural polymers and inorganic nanomaterials. Biopolymers such as alginate, cellulose, starch, gelatin, chitosan, etc. have been considered extensively and provided composites with better electrical and mechanical thermal properties. Fe₃O₄ NPs incorporated in a polymer and biopolymer matrix is a good instance of the functional nanostructure, which has been able to enhance the properties of both ingredients. These hybrids can have impressive applications in various scopes such as magneto-optical storage, electromagnetic interference shielding, catalyst, water remediation, biomedical sensing, and so on. In this study, we have tried to briefly introduce Fe₃O₄ NPs, investigate the green and sustainable methods that have been suggested for its synthesis and review recent utilization of their biopolymeric nanocomposite (NC) including starch, chitosan, dextrin, etc. as catalysts and photocatalysts.

NO oxidation over Fe-based catalysts supported on montmorillonite K10, γ-alumina and ZSM-5 with gas-phase H2O2

The catalytic gas-phase H₂O₂ oxidation of NO was achieved over Fe-based catalysts supported on montmorillonite K10, γ-alumina and ZSM-5. ESR tests illustrate that the three catalysts can catalyze decomposition of H₂O₂ yielding highly reactive hydroxyl radicals, of which Fe/K10 has the fastest rate, followed by Fe/γ-alumina. Fe³⁺ in Fe/K10 and Fe/γ-alumina show lower density of electron cloud due to a strong interaction between Fe³⁺ and the support, which benefits the electron transfer from the H₂O₂ to Fe³⁺, thus favoring the production of hydroxyl radicals. Fe species exist on the surface of Fe/K10 mainly in the form of Fe₂O₃, whereas Fe species of Fe/γ-alumina and Fe/ZSM-5 exist mainly in the form of Fe₃O₄, and it is found that Fe₂O₃ is more active than Fe₃O₄ in catalytic gas-phase H₂O₂ oxidation of NO. Interestingly, Fe/ZSM-5 has the lowest efficiency in generating hydroxyl radicals, its NO removal efficiency is 90%, which is much higher than 47.5% for Fe/γ-alumina and 62.3% for Fe/K10. In-situ IR results suggested that Fe/ZSM-5 are dual functional in oxidation of NO, that is, whether both Fe ion sites and Brønsted acid sites collectively provide the catalytic functionality. In the meantime, a possible reaction mechanism on catalytic gas-phase H₂O₂ oxidation of NO over Brønsted acid sites is proposed.

One-pot sonochemical synthesis of magnetite@reduced graphene oxide nanocomposite for high performance Li ion storage

In this research, we introduce a one-pot sonochemical method for the fabrication of magnetite@reduced graphene oxide (Fe₃O₄@rGO) nanocomposite as anode material for Li-ion batteries. Fe₃O₄@rGO is synthesized under ultrasonic irradiations by using iron (II) salt and GO as raw materials. An in-situ oxidation-reduction occurs between GO and Fe²⁺ during the ultrasonic chemical reaction process. Fe₃O₄ particles with the size of ∼20 nm are uniformly deposited on the surface of rGO nanosheets. The electrochemical activity of Fe₃O₄@rGO is systematically evaluated as an anode material in Li-ion battery. Li-ion cells using Fe₃O₄@rGO as electrode deliver high discharge and charge capacities of 1433.6 and 907.8 mAh g^-1 in the initial cycle at 200 mA g^-1. Even performed at 500 and 5000 mA g^-1, it is able to deliver reversible capacities of 846.4 and 355.6 mAh g^-1, respectively, demonstrating outstanding Li-ion storage performance. This research presents a straightforward and efficient method for the fabrication of Fe₃O₄@rGO, which holds great potential in synthesis of other metal oxides on graphene sheets.