The past decade has witnessed a phenomenal rise in nanotechnology research due to its broad range of applications in diverse fields including food safety, transportation, sustainable energy, environmental science, catalysis, and medicine. The distinctive properties of nanomaterials (nano-sized particles in the range of 1 to 100 nm) make them uniquely suitable for such wide range of functions. The nanoparticles when manufactured using green synthesis methods are especially desirable being devoid of harsh operating conditions (high temperature and pressure), hazardous chemicals, or addition of external stabilizing or capping agents. Numerous plants and microorganisms are being experimented upon for an eco–friendly, cost–effective, and biologically safe process optimization. This review provides a comprehensive overview on the green synthesis of metallic NPs using plants and microorganisms, factors affecting the synthesis, and characterization of synthesized NPs. The potential applications of metal NPs in various sectors have also been highlighted along with the major challenges involved with respect to toxicity and translational research.

Green Synthesis of Metallic Nanoparticles: Applications and Limitations

The sustainable growth of any society is in direct proportion with developing novel methods and technologies for the management of its environmental quality. The use of Magnetic Nanoparticles (MNPs) has emerged as an efficient tool for remediation of wastewater owing to its intrinsic qualities including size, surface effect, quantum effect, etc. These intrinsic properties of MNPs have diversified their application in managing the qualitative stress on water resources. The present review aims to assess the use of MNPs in removing organic and inorganic contaminants from wastewater. Insights into various synthesis methods and their effects on contaminant removal are also presented. It is reported that MNPs provide target specificity and cost-effectiveness as compared to conventional treatment methods. Moreover, the biological synthesis of MNPs is proven to be eco-friendly and aids in sustainable development. Nearly 100% removal of various types of contaminants such as pharmaceuticals and personal care products, dyes, pesticides, heavy metals, etc. can be achieved through MNPs. Some MNPs have shown a magnetic saturation reaching up to 70 emu/g, and recycling up to 5 cycles with >95% removal efficiency. High pollutant removal efficiency (>98%) can also be achieved in a short time (within 5 min) by MNPs. It is noteworthy that, nanosorption along with the redox reactions are the most frequently used and efficient mechanisms of contaminant removal from wastewater samples.

Synthesis and characterization of magnetic nanoparticles, and their applications in wastewater treatment: A review

Impact of Cu2+ cations substitution on structural, morphological, optical and magnetic properties of Co1-xCuxFe2O4 nanoparticles synthesized by a facile hydrothermal approach

Recent advances on synthesis, characterization and high frequency applications of Ni-Zn ferrite nanoparticles

Fossil fuel depletion and pollution are calling for alternative, renewable energies such as biofuels. Actual challenges include the design of efficient processes and catalysts to convert various feedstocks into biofuels. Here, we review nanoferrites heterogeneous catalysts to produce biodiesel from soybean and canola oil. For that, transesterification is the main synthesis route and offers simplicity, cost-effectiveness, better process control, and high conversion yield. Catalysis with nanoferrites and composites allow to obtain yields higher than 95% conversion with less than 5.0 wt.% of catalyst loading at 80 °C in 1–2 h. More than 90% conversion yields can be achieved with a moderate alcohol/oil molar ratio, i.e., between 12:1 to 16:1. Catalyst recovery is easy due to the magnetic properties of nanoferrite, which can be effectively reused up to 4 times with less than 10% loss of catalytic efficiency.

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Nanoferrites heterogeneous catalysts for biodiesel production from soybean and canola oil: a review.

Recent advances in synthesis, characterization, and applications of nanoparticles for contaminated water treatment- A review

The water treatment process by removing heavy metals from polluted sources is explained in detail. Various detection and removal techniques and their modeling for heavy metal removal are reviewed. Detection of heavy metals is possible by several optical, spectroscopic and electrochemical methods. Due to their high efficiencies and accurate evaluation capabilities, several spectroscopic as well as other techniques like neutron activation analysis and X-ray fluorescence are discussed and found highly significant. Adsorption, photocatalysis, ion exchange, electrochemical methods, membrane filtration, chemical precipitation, and forward osmosis are the most frequently used techniques for heavy metal removal, being up to 100 % efficient to detect and remove heavy metal ions. The design, operation, and key features of all techniques are explained. The regeneration of used adsorbents, resins, and other materials to remove heavy metals is found as key step in the wastewater treatment process. 

Recent Advances in Detection and Removal of Heavy Metals from Contaminated Water

NixZn1-xFe2O4 (x = 0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) nanoferrites were synthesized using the citrate precursor method with high-purity metal nitrates and citric acid as synthesis precursors. For a detailed analysis of the structural, optical and magnetic properties of these nanoferrites sintered at 700 °C for 3 h, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM) tests were done. The analysis of XRD patterns of the powdered samples revealed that the nanoferrites have a spinel structure, and the crystallite size of the nanoferrites ranged from 23 to 31 nm. The nanoferrite samples were found with a maximum porosity of 57% at x = 0.5 which indicated the higher adsorption capacity of the materials. The density of these nanoferrites varied from 2.318 to 2.590 g/cm3 with the change in their crystallite size and lattice parameter. FTIR spectroscopy also revealed two prominent peaks between 542–582 and 402–415 cm−1, representing the tetrahedral and octahedral site occupancies, occupied by Ni2+, Zn2+ and Fe3+ ions. These peaks indicated the spinel structure of the nanoferrites. The magnetic behaviour of the nanoferrites was analysed from the hysteresis loop obtained from VSM data. It was observed that the nanoferrites are highly magnetic as the value of specific saturation magnetization varied from 1.31 to 63.31 emu/g with the variation in concentration of Ni2+ metal ions ranging from x = 0.0 to x = 1.0. High values of anisotropic constant were observed, which varied from 0.00147 $$\times$$
 105 to 0.16218 $$\times$$
 105 erg/g.

Pinki Punia

Papers

Recent advances in synthesis, characterization, and applications of nanoparticles for contaminated water treatment- A review

Recent Advances in Detection and Removal of Heavy Metals from Contaminated Water

Microstructural, Optical and Magnetic Study of Ni–Zn Nanoferrites

Adsorption of Cd and Cr ions from industrial wastewater using Ca doped Ni–Zn nanoferrites: Synthesis, characterization and isotherm analysis

Cobalt Nanoferrites: a Review on Synthesis, Characterization, and Applications