scholarly journals Magnetic Iron Oxide Colloids for Environmental Applications

2021 ◽  
Author(s):  
Alvaro Gallo-Cordova ◽  
Daniela Almeida Streitwieser ◽  
María del Puerto Morales ◽  
Jesús G. Ovejero
Keyword(s):  
Iron Oxide ◽  
Low Cost ◽  
High Surface ◽  
Volume Ratio ◽  
Efficient Production ◽  
Ionic Exchange ◽  
Magnetic Iron Oxide ◽  
Oil Crops ◽  
Organic Pollutants Removal ◽  
Pollutants Removal

This chapter deals with magnetic colloids with catalytic properties for the treatment of polluted waters and the efficient production of fuel alternatives. This kind of materials presents great advantages such as high surface/volume ratio, reproducibility, selectivity, ability to be magnetic harvested, functionalizable surfaces (e.g. with tunable pores and selective chelators deposited on them), high efficiencies and reusability. In particular, this chapter will consider the case of magnetic iron oxide colloids, which can be easily synthesized at low cost, are biocompatible and presents a well-developed surface chemistry. The most common techniques for the synthesis and functionalization of these magnetic nanoparticles will be reviewed and summarized. The iron oxide nanoparticles present outstanding properties that can be exploited in different aspect of the wastewater treatment such as heavy metals and organic pollutants removal by ionic exchange or adsorption, and degradation of the contaminants by advanced oxidation processes, among others. In the field of alternative energies, they have also been used as catalysts for biofuels production from oil crops, in Fischer-Tropsch reactions for liquid hydrocarbons and many other processes with potential environmental impact.

scholarly journals Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications

2020 ◽  
Vol 18 (1) ◽  
pp. 1148-1166
Author(s):  
Ganjar Fadillah ◽  
Septian Perwira Yudha ◽  
Suresh Sagadevan ◽  
Is Fatimah ◽  
Oki Muraza
Keyword(s):  
Iron Oxide ◽  
Water Treatment ◽  
Photocatalytic Oxidation ◽  
Low Cost ◽  
Synthesis Method ◽  
Chemical Oxidation ◽  
Magnetic Iron Oxide ◽  
Oxidation Processes ◽  
Recent Developments ◽  
Physical And Chemical

AbstractPhysical and chemical methods have been developed for water and wastewater treatments. Adsorption is an attractive method due to its simplicity and low cost, and it has been widely employed in industrial treatment. In advanced schemes, chemical oxidation and photocatalytic oxidation have been recognized as effective methods for wastewater-containing organic compounds. The use of magnetic iron oxide in these methods has received much attention. Magnetic iron oxide nanocomposite adsorbents have been recognized as favorable materials due to their stability, high adsorption capacities, and recoverability, compared to conventional sorbents. Magnetic iron oxide nanocomposites have also been reported to be effective in photocatalytic and chemical oxidation processes. The current review has presented recent developments in techniques using magnetic iron oxide nanocomposites for water treatment applications. The review highlights the synthesis method and compares modifications for adsorbent, photocatalytic oxidation, and chemical oxidation processes. Future prospects for the use of nanocomposites have been presented.

Effect of current density on the porous silicon preparation as gas sensors**

2021 ◽  
Vol 30 (1) ◽  
pp. 257-264
Author(s):  
Muna H. Kareem ◽  
Adi M. Abdul Hussein ◽  
Haitham Talib Hussein
Keyword(s):  
Porous Silicon ◽  
Gas Sensors ◽  
Current Density ◽  
Room Temperature ◽  
Low Cost ◽  
High Surface ◽  
Volume Ratio ◽  
Etching Time ◽  
Force Microscopy ◽  
Materials Used

Abstract In this study, porous silicon (PSi) was used to manufacture gas sensors for acetone and ethanol. Samples of PSi were successfully prepared by photoelectrochemical etching and applied as an acetone and ethanol gas sensor at room temperature at various current densities J= 12, 24 and 30 mA/cm2 with an etching time of 10 min and hydrofluoric acid concentration of 40%. Well-ordered n-type PSi (100) was carefully studied for its chemical composition, surface structure and bond configuration of the surface via X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy and photoluminescence tests. Results showed that the best sensitivity of PSi was to acetone gas than to ethanol under the same conditions at an etching current density of 30 mA/cm2, reaching about 2.413 at a concentration of 500 parts per million. The PSi layers served as low-cost and high-quality acetone gas sensors. Thus, PSi can be used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The material has an exceptionally high surface-to-volume ratio (increasing surface area) and demonstrates ease of fabrication and compatibility with manufacturing processes of silicon microelectronics.

scholarly journals A Review of Carbon Nanotubes-Based Gas Sensors

2009 ◽  
Vol 2009 ◽  
pp. 1-24 ◽  
Author(s):  
Yun Wang ◽  
John T. W. Yeow
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Low Cost ◽  
High Surface ◽  
Hollow Structure ◽  
Volume Ratio ◽  
Fast Response ◽  
Sensing Technology ◽  
Structure Of Nanomaterials

Gas sensors have attracted intensive research interest due to the demand of sensitive, fast response, and stable sensors for industry, environmental monitoring, biomedicine, and so forth. The development of nanotechnology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. The extremely high surface-to-volume ratio and hollow structure of nanomaterials is ideal for the adsorption of gas molecules. Particularly, the advent of carbon nanotubes (CNTs) has fuelled the inventions of gas sensors that exploit CNTs' unique geometry, morphology, and material properties. Upon exposure to certain gases, the changes in CNTs' properties can be detected by various methods. Therefore, CNTs-based gas sensors and their mechanisms have been widely studied recently. In this paper, a broad but yet in-depth survey of current CNTs-based gas sensing technology is presented. Both experimental works and theoretical simulations are reviewed. The design, fabrication, and the sensing mechanisms of the CNTs-based gas sensors are discussed. The challenges and perspectives of the research are also addressed in this review.

scholarly journals Exploration of Microbial Factories for Synthesis of Nanoparticles – A Sustainable Approach for Bioremediation of Environmental Contaminants

2021 ◽  
Vol 12 ◽  
Author(s):  
Riti T. Kapoor ◽  
Marcia R. Salvadori ◽  
Mohd Rafatullah ◽  
Masoom R. Siddiqui ◽  
Moonis A. Khan ◽  
...  
Keyword(s):  
Low Cost ◽  
High Surface ◽  
Pollution Abatement ◽  
Chemical Properties ◽  
Volume Ratio ◽  
Production Method ◽  
Research Field ◽  
Renewable Materials ◽  
Synthesis Of Nanoparticles ◽  
Nanoparticles Synthesis

The nanomaterials synthesis is an intensifying research field due to their wide applications. The high surface-to-volume ratio of nanoparticles and quick interaction capacity with different particles make them as an attractive tool in different areas. Conventional physical and chemical procedures for development of metal nanoparticles become outmoded due to extensive production method, energy expenditure and generation of toxic by-products which causes significant risks to the human health and environment. Hence, there is a growing requirement to search substitute, non-expensive, reliable, biocompatible and environmental friendly methods for development of nanoparticles. The nanoparticles synthesis by microorganisms has gained significant interest due to their potential to synthesize nanoparticles in various sizes, shape and composition with different physico-chemical properties. Microbes can be widely applied for nanoparticles production due to easy handling and processing, requirement of low-cost medium such as agro-wastes, simple scaling up, economic viability with the ability of adsorbing and reducing metal ions into nanoparticles through metabolic processes. Biogenic synthesis of nanoparticles offers clean, non-toxic, environmentally benign and sustainable approach in which renewable materials can be used for metal reduction and nanoparticle stabilization. Nanomaterials synthesized through microbes can be used as a pollution abatement tool as they also contain multiple functional groups that can easily target pollutants for efficient bioremediation and promotes environmental cleanup. The objective of the present review is to highlight the significance of micro-organisms like bacteria, actinomycetes, filamentous fungi, yeast, algae and viruses for nanoparticles synthesis and advantages of microbial approaches for elimination of heavy metals, dyes and wastewater treatment.

scholarly journals Research Progress on the Applications of Electrospun Nanofibers in Catalysis

Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 9
Author(s):  
M. Olga Guerrero-Pérez
Keyword(s):  
Low Cost ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Electrospun Nanofibers ◽  
Internal Diffusion ◽  
Research Progress ◽  
Bibliographic Analysis ◽  
Low Resistance ◽  
Electro Catalysis

During the last two decades, electrospinning has become a very popular technique for the fabrication of nanofibers due to its low cost and simple handling. Nanofiber materials have found utilization in many areas such as medicine, sensors, batteries, etc. In catalysis, these materials also present important advantages, since they present a low resistance to internal diffusion and a high surface area to volume ratio. These advantages are mainly due to the diameter–length proportion. A bibliographic analysis on the applications of electrospun nanofibers in catalysis shows that there are two important groups of catalysts that are being investigated, based on TiO2 and in carbon materials. The main applications found are in photo- and in electro-catalysis. The present study contributes by reviewing these catalytic applications of electrospun nanofibers and demonstrating that they are promising materials as catalysts, underlining some works to prove the advantages and possibilities that these materials have as catalysts. On one hand, the possibilities of synthesis are almost infinite, since with coaxial electrospinning quite complex nanofibers with different layers can be prepared. On the other hand, the diameter and other properties can be controlled by monitoring the applied voltage and other parameters during the synthesis, being quite reproducible procedures. The main advantages of these materials can be grouped in two: one related to their morphology, as has been commented, relative to their low resistance and internal diffusion, that is, their fluidynamic behavior in the reactor; the second group involves advantages related to the fact that the active phases can be nanoscaled and dispersed, improving the activity and selectivity in comparison with conventional catalytic materials with the same chemical composition.

scholarly journals Starch-Based Hybrid Nanomaterials for Environmental Remediation

2021 ◽  
Author(s):  
Ashoka Gamage ◽  
Thiviya Punniamoorthy ◽  
Terrence Madhujith
Keyword(s):  
Metal Oxide ◽  
Environmental Remediation ◽  
Membrane Filtration ◽  
Anthropogenic Activities ◽  
Low Cost ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Hybrid Nanomaterials ◽  
Metal Metal

Environmental pollution is becoming a major global issue with increasing anthropogenic activities that release massive toxic pollutants into the land, air, and water. Nanomaterials have gained the most popularity in the last decades over conventional methods because of their high surface area to volume ratio and higher reactivity. Nanomaterials including metal, metal oxide, zero-valent ions, carbonaceous nanomaterials, and polymers function as adsorbents, catalysts, photocatalysts, membrane (filtration), disinfectants, and sensors in the detection and removal of various pollutants such as heavy metals, organic pollutants, dyes, industrial effluents, and pathogenic microbial. Polymer-inorganic hybrid materials or nanocomposites are highly studied for the removal of various contaminants. Starch, a heteropolysaccharide, is a natural biopolymer generally incorporated with other metal, metal oxide, and other polymeric nanoparticles and has been reported in various environmental remediation applications as a low-cost alternative for petroleum-based polymers. Therefore, this chapter mainly highlights the various nanomaterials used in environmental remediation, starch-based hybrid nanomaterials, and their application and limitations.

scholarly journals CMOS-Compatible and Low-Cost Thin Film MACE Approach for Light-Emitting Si NWs Fabrication

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 966
Author(s):  
Antonio Alessio Leonardi ◽  
Maria José Lo Faro ◽  
Alessia Irrera
Keyword(s):  
Silicon Nanowires ◽  
Low Cost ◽  
Quantum Confinement Effect ◽  
High Surface ◽  
Volume Ratio ◽  
Cmos Technology ◽  
High Density ◽  
Synthesis Methods ◽  
Light Emitting ◽  
Strong Control

Silicon nanowires (Si NWs) are emerging as an innovative building block in several fields, such as microelectronics, energetics, photonics, and sensing. The interest in Si NWs is related to the high surface to volume ratio and the simpler coupling with the industrial flat architecture. In particular, Si NWs emerge as a very promising material to couple the light to silicon. However, with the standard synthesis methods, the realization of quantum-confined Si NWs is very complex and often requires expensive equipment. Metal-Assisted Chemical Etching (MACE) is gaining more and more attention as a novel approach able to guarantee high-quality Si NWs and high density with a cost-effective approach. Our group has recently modified the traditional MACE approach through the use of thin metal films, obtaining a strong control on the optical and structural properties of the Si NWs as a function of the etching process. This method is Complementary Metal-Oxide-Semiconductors (CMOS)-technology compatible, low-cost, and permits us to obtain a high density, and room temperature light-emitting Si NWs due to the quantum confinement effect. A strong control on the Si NWs characteristics may pave the way to a real industrial transfer of this fabrication methodology for both microelectronics and optoelectronics applications.

Functionalized Magnetic Nanoparticles for Environmental Remediation

2017 ◽  
pp. 705-741
Author(s):  
Ravindra Kumar Gautam ◽  
Shivani Soni ◽  
Mahesh Chandra Chattopadhyaya
Keyword(s):  
Heavy Metals ◽  
Magnetic Nanoparticles ◽  
Environmental Remediation ◽  
Anthropogenic Activities ◽  
Low Cost ◽  
High Surface ◽  
High Surface Area ◽  
Toxic Metal ◽  
Volume Ratio ◽  
Removal Of Heavy Metals

Water pollution by anthropogenic activities is proving to be of critical concern as the heavy metals affect aquatic organisms and can quickly disperse to large distances. This poses a risk to both human health and the aquatic biota. Hence, there is a need to treat the wastewater containing toxic metals before they are discharged into the water bodies. During recent years, magnetic nanoparticles came to the foreground of scientific interest as a potential adsorbent of novel wastewater treatment processes. Magnetic nanoparticles have received much attention due to their unique properties, such as extremely small size, high surface-area-to-volume ratio, surface modifiability, multi functionality, excellent magnetic properties, low-cost synthesis, and great biocompatibility. The multi-functional magnetic nanoparticles have been successfully applied for the reduction of toxic metal ions up to ppb level in waste-treated water. This chapter highlights the potential application of magnetic nanoparticles for the removal of heavy metals.

Functionalized Magnetic Nanoparticles for Environmental Remediation

2015 ◽  
pp. 518-551 ◽  
Author(s):  
Ravindra Kumar Gautam ◽  
Shivani Soni ◽  
Mahesh Chandra Chattopadhyaya
Keyword(s):  
Heavy Metals ◽  
Magnetic Nanoparticles ◽  
Environmental Remediation ◽  
Anthropogenic Activities ◽  
Low Cost ◽  
High Surface ◽  
High Surface Area ◽  
Toxic Metal ◽  
Volume Ratio ◽  
Removal Of Heavy Metals

Water pollution by anthropogenic activities is proving to be of critical concern as the heavy metals affect aquatic organisms and can quickly disperse to large distances. This poses a risk to both human health and the aquatic biota. Hence, there is a need to treat the wastewater containing toxic metals before they are discharged into the water bodies. During recent years, magnetic nanoparticles came to the foreground of scientific interest as a potential adsorbent of novel wastewater treatment processes. Magnetic nanoparticles have received much attention due to their unique properties, such as extremely small size, high surface-area-to-volume ratio, surface modifiability, multi functionality, excellent magnetic properties, low-cost synthesis, and great biocompatibility. The multi-functional magnetic nanoparticles have been successfully applied for the reduction of toxic metal ions up to ppb level in waste-treated water. This chapter highlights the potential application of magnetic nanoparticles for the removal of heavy metals.

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