Green Synthesis of Cobalt Ferrite Nanoparticles: An Emerging Material for Environmental and Biomedical Applications

Methods that allow for high-throughput synthesis of magnetic nanoparticles are necessary to more feasibly fabricate materials for real-world applications. To accomplish this, in this article, we describe a versatile electrospray-based synthesis method for the synthesis of magnetic cobalt ferrite nanoparticles. This method has the potential to be readily scaled up using methods similar to those currently used in place for the large-scale electrospinning of fibers. To mitigate film formation as often seen with electrospraying ceramics onto a flat plate collector, we developed a method where the magnetic cobalt ferrite nanoparticles were electrosprayed into a silicone oil–based liquid collector. The as-sprayed particles were then crystalized by salt calcining with sodium chloride at 800 °C. The synthesized magnetic nanoparticles obtained using this method had an average particle diameter of 20.7 ± 11.5 nm. This liquid collection method for the synthesis of cobalt ferrite also presents a versatile platform for the synthesis of a wide range of functional nanomaterials and nanocomposites.

In the recent years, nanomaterials are widely used in various fields, such as environmental remediation processes, energy production, industries, and medicines, but the synthesis of nanomaterials using the conventional chemical methods has various adverse effects such as high energy consumption, environmental pollution, and health problems. To address these challenges, green synthetic methods can be applied in which plant extracts are used rather than the toxic chemical substances. Compared to the traditional chemical methods, green synthesis is more beneficial as it is environment-friendly, cost-effective, and biologically safe. In this review, we have discussed about the adverse effect of chemical synthetic methods on the environment. To protect the environment from the harsh chemicals, green synthetic methods can be applied for the synthesis of metal oxide nanoparticles. Here, we have mainly emphasized on the green synthesis of some metal oxide nanoparticles such as SnO2, ZnO, and CuO. In this procedure, extracts of various plant parts (such as fruits, leaf, root), microbes, and ionic liquids can be used as precursors. These “green” metal oxide nanoparticles exhibit high biocompatibility and low toxicity, which enables them for their wide applications in various fields such as environmental remediation processes and removal of various organic pollutants. This chapter also discussed the applications of green synthesized metal oxide nanoparticles in the photocatalytic degradation of various toxic dyes from water bodies. In the end, we have also discussed about the future perspective of green synthetic methods and photocatalytic applications of metal oxide nanoparticles.KeywordsGreen synthesisSnO2ZnOCuOPhotocatalysisDyes

24 - Mechanistic aspects and rate-limiting steps in green synthesis of metal and metal oxide nanoparticles and their potential in photocatalytic degradation of textile dye

Starch from the stem of sago palm (Metroxylon sagu) was demonstrated as a chelating agent in the sol-gel synthesis of cobalt ferrite (CoFe2O4) nanoparticles. Variations in the weight ratio of metal nitrates to sago starch from 1:8 to 1:12 led to the particle size of 30–500 nm. However, further increase in sago starch to 1:16 resulted in ferrimagnetic hysteresis loops with a reduced coercive field and magnetization due to the second phase of hematite (α-Fe2O3). The synthesis conditions and products were comparable to those of the polyvinyl alcohol (PVA) sol-gel synthesis. Thus, sago starch can be implemented in the green synthesis of nanosized ferrites whose magnetic properties are tuned by varying of sol-gel compositions for each application.

Green synthesis, an emerging field in bionanotechnology, refers to the utilization of non-toxic, biologically safe, and eco-friendly substances for the synthesis of desired materials. It provides both economic and environmental benefits along with simple, cost-effective, and reproducible synthesis approaches that result in the development of stable materials. The green synthesis approaches use living biotemplates, including plants and different microorganisms such as viruses, bacteria, fungi, algae, and actinomycetes. The various metabolites present in different parts of the plants, such as leaves, fruits, seeds, flower, and others, serve as the reducing and stabilizing agents. At the same time, the diverse surface chemistry of microorganisms enables them to convert different substrates into a variety of nanomaterials. This review briefly describes the concept of 'green synthesis' and provides an overview of controlled and green synthesis of nanomaterials using the plants and microbial cells as biotemplates. It also discusses the effect of different reaction conditions such as temperature, pH, reaction time, precursor concentration, and the post-synthesis processing of nanoparticles (NPs) on the material properties. It further describes the applications of different NPs in pharmaceutical and environment sectors by considering their diverse antimicrobial, anticancer, antioxidant, antiviral, antimalarial, reduction, and catalytic properties. Finally, it describes various future perspectives of nanomaterials to broaden the understanding of their synthesis mechanism and expand their applications to other fields.

Bioinspired synthesis of iron-based nanomaterials and nanocomposite: For environmental remediation

Chapter 2 - Green synthesis and methodologies of nanomaterials: State of the art

This study explores the photocatalytic degradation of Fast Green FCF dye using nickel oxide (NiO) nanoparticles synthesized through a green synthesis approach. The efficiency of the degradation process was found to be influenced by several parameters including pH, the amount of NiO catalyst, dye concentration and light intensity. Radical scavenging experiments revealed that hydroxyl radicals are primarily responsible for the dye's degradation. The reaction kinetics was monitored using spectrophotometers and followed a pseudo-first-order model. The photocatalytic process was sensitive to variations in operational conditions such as catalyst dosage, dye concentration, pH level and light exposure. Experimental evidence supports a photochemical mechanism for the breakdown of Fast Green FCF.

In recent years, there has been a growing interest in developing environmentally and sustainable methods for the synthesis of nanomaterials (NMs). Among various NMs, ceria-based NMs have gained significant attention due to their unique properties and diverse applications. This chapter provides a comprehensive overview of the green synthesis approaches employed for the fabrication of ceria-based NMs and their subsequent applications. The chapter begins with an introduction to ceria-based NMs, highlighting their exceptional physicochemical properties such as high surface area, redox capabilities, and oxygen storage capacity. Subsequently, it delves into the concept of green synthesis, emphasizing the significance of using environmentally benign routes for NMs fabrication. Various green synthesis methods, including biological, template-mediated, and microwave-assisted techniques, are discussed in detail, highlighting their advantages, limitations, and applicability to ceria-based NMs. Furthermore, the chapter explores the wide-ranging applications of ceria-based NMs in different fields, such as catalysis, energy storage and conversion, environmental remediation, and biomedical applications. Specific examples and case studies are presented to illustrate the effectiveness of ceria-based NMs in these applications. Additionally, the chapter discusses the potential challenges and future perspectives associated with the green synthesis and applications of ceria-based NMs, including scalability, stability, and toxicity considerations. By adopting sustainable and environmentally friendly approaches, the synthesis and applications of ceria-based NMs can contribute to the development of cleaner and more efficient technologies for a sustainable future.

Nickel ferrite (NiFe2O4) spinel-structured nanoparticles (NPs) were synthesized by a green synthesis approach using Hydrangea paniculata flower extract. Green synthesis of NPs was preliminary monitored by a color change. Further confirmation was carried out using different techniques. X-ray diffraction analysis confirmed the cubic crystalline system (fcc) of NiFe2O4. Energy-dispersive spectrum analysis showed the presence of iron, nickel, oxygen, and carbon. Scanning electron microscopy revealed the agglomerating nature of the NPs (30–50 nm). The specific surface area was found to be 46.73 m2/g, revealing the average size D of NPs to be 24 nm. Transmission electron microscopy confirmed the spherical, oval, and irregular shapes of the NPs with a size range between 10 nm and 45 nm, and an average size of 28 nm. The magnetization of the obtained NiFe2O4 NPs in a high magnetic field of 20 kOe was found to be 20 emu/g. The values of remanent magnetization (Mr) and coercive field (Hc) were found to be 1.1 emu/g and 28 Oe, respectively. In the process of magnetization reversal (with a small value of Mr/Ms, 0.055), NiFe2O4 NPs had a loop with low energy loss, showing that the obtained NiFe2O4 NPs were soft magnetic materials. The magnetization curve with a sigmoidal shape indicated that the obtained NiFe2O4 NPs are super-paramagnetic material. In addition, the comparison of green synthesis with the methods available in the literature proved that the green synthesis is the best method. Thus, it is clear that green synthesis is a novel eco-friendly approach for the synthesis of magnetic NiFe2O4 NPs.

Active food packaging has gained increasing attention due to their potential in extending food shelf life. To improve their performance, nanomaterials have been popularly employed in view of their high aspect ratio and numerous active sites. Here, we mainly focus on nanomaterials-enabled active food packaging and their application to delay food deterioration and extend food shelf life. Different dimensions of nanomaterials, as well as their green synthesis approaches, are reviewed. It is found that plant extracts, agricultural by-products, microbes, and microwave-assisted approaches are commonly used in their green synthesis. Then, recent progress of nanomaterials-enabled active food packaging to delay food deterioration and extend food shelf life is summarized. Furthermore, the concerns and future prospects of nanomaterials-enabled active food packaging are discussed.

Magnetic nanoparticles have attracted increasingly attention due to their potential applications in many industrial fields, even extending their use in biomedical applications. In the latter contest the main features of magnetic nanoparticles are the possibility to be driven by external magnetic fields, the ability to pass through capillaries without occluding them and to absorb and convert electromagnetic radiation in to heat (Magnetic Fluid Hyperthermia). The main challenges of the current works on hyperthermia deal with the achievement of highly efficiency magnetic nanoparticles, the surface grafting with ligands able to facilitate their specific internalisation in tumour cells and the design of stealth nanocomposites able to circulate in the blood compartment for a long time. This article presents the synthesis of cobalt ferrite nanoparticles dispersed in diethylene glycol via the so called polyol strategy and the crystal size control through successive synthesis steps. Preliminary heat dissipation evaluations on the prepared samples were carried out and the question of how particles sizes affect their magnetic and hyperthermic properties was addressed as well. Furthermore we will present how surface chemistry can be modified in order to change the dispersity of the product without affecting magnetic and hyperthermic properties. .

It is an age of nanomaterials. Nanotechnology has revolutionized the scientific world. Every sphere of technology has benefited significantly by using nanomaterials. A number of physical and chemical methods are being used for the synthesis of nanomaterials. In recent years, much emphasis is placed on green synthesis, particularly by using plant extracts or microorganisms. This is useful for promoting environmental sustainability. Microwave heating and ultrasound techniques are also being used for the synthesis of different types of nanomaterials. Green synthesis is a more advanced method of synthesizing nanomaterials over other methods because of its simplicity, lower cost, and relatively higher reproducibility. Plants produce more stable nanoparticles compared to other means, and it is straightforward to scale up. The risk of contamination is also lower. In this article, different methods of green synthesis of nanomaterials and applications have been reviewed and discussed.

One-minute and green synthesis of magnetic iron oxide nanoparticles assisted by design of experiments and high energy ultrasound: Application to biosensing and immunoprecipitation

Green and sustainable synthesis of nanomaterials: Recent advancements and limitations