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4: Photocatalytic Activity Toward Cost-Effective Decomposition of Toxic Organic Dyes
Published in A. Pandikumar, K. Jothivenkatachalam, S. Moscow, Heterojunction Photocatalytic Materials, 2022
K. Ravichandran, M. Baneto, E. Sindhuja, K. Shantha Seelan
To overcome the drawbacks, recently several strategies have been adopted to increase the photocatalytic degradation efficiency of ZnO: (i) doping metals (e.g., Ag, Cu, Al, Fe, Mn, Au, Pt, Ti, Co, Ni, Eu, Ce, Sr, Mo, W, V, Bi, Y, Pd), (ii) nonmetals (C, N, S, F, P, B), and (iii) carbonaceous materials (graphene, graphene oxide (GO), g-C3N4) and reduced graphene oxide (rGO), (iv) co-doping with metal–nonmetal and metal–metal, and (v) coupling with other semiconductors (e.g., ZnO–TiO2, ZnO–SnO2) [48–51]. Because of the toxicity and cytotoxic potential, metal oxide materials may result in some adverse effect on health [52]. The formation of heterojunction between metal oxide and carbonaceous materials leads to an enhanced photocatalytic activity by altering the structural and electronic properties of the system. The addition of carbonaceous materials drastically reduces the recombination of charge carriers by trapping photogenerated electrons.
Applications of Nanotechnology to Bioprocessing
Published in Yubing Xie, The Nanobiotechnology Handbook, 2012
Susan T. Sharfstein, Sarah Nicoletti
Metal oxides are compounds formed between metals and oxygen, typically an oxygen anion and metal cation. Depending on the metal associated with the oxide, the physical and chemical properties of that material can be different. Metallic oxides are large structures that contain metal ions and oxide ions. The attractions between these ions are strong, requiring a lot of energy to break the bonds, leading to high melting and boiling points. These oxides are also incapable of conducting electricity in a solid state but electrolysis is possible in the molten state. Molten metal oxides can conduct electricity because of the movement and discharge of the ions present. Some metal oxides also have magnetic properties, which can make them useful in a variety of fields. One issue associated with metal oxides is that they need to be protected with a polymer or other materials to prevent them from oxidizing, potentially causing a loss of their magnetism (Lu et al. 2007). Nanoscale metal oxides are currently used for a vast number of applications including gas sensing, solar cells, fuel cells, and data storage. Metal oxides are also increasingly used for the development of biosensors, as well as bioinorganic nanoscaffolds. The metal oxides used include iron oxide, aluminum oxide, nickel oxide, and zinc oxide.
One-Dimensional Metal Oxide Nanostructures in Sensor Applications
Published in Zainovia Lockman, 1-Dimensional Metal Oxide Nanostructures, 2018
Ahalapitiya H. Jayatissa, Bharat R. Pant
Metal oxides have been extensively investigated for applications in gas sensors, biosensors, photodetectors and humidity sensors over the past two decades (Seiyama et al., 1962, Kolmakov and Moskovits, 2004, Kolmakov et al., 2005, Chen et al., 2010, Kumar et al., 2011, Devan et al., 2012, Arafat et al., 2012, Li et al., 2012, Jeong et al., 2014, Zhang et al., 2017). Metal oxides are composed of positive metallic ions and negative oxygen ions, and the strong bond between metal and oxygen made them solid and firm (Devan et al., 2012). Some of the unique properties that make metal oxides suitable for sensing applications include stability, high surface to volume ratio, easy fabrication, good selectivity and ability to sense a wide range of gases. Metal oxides are thermally and chemically stable because their s-shells are totally filled, but their d-shells are not completely filled, which makes them useful for electronic device applications. Other attractive properties of 1-D metal oxides are good thermal and chemical stabilities and low weight of electronic devices fabricated with 1-D materials. There are two types of metal oxides, n-type and p-type. For n-type metal oxides, the majority of charge carriers are electron whereas, for p-type metal oxides, the majority of charge carrier are holes (Zhang et al., 2017). The dramatic change in resistance of semiconductor metal oxide due to adsorption and desorption of gases was first reported by Seiyama et al. in 1962. The 1-D metal oxides have a large surface to volume ratio due to the high ratio of length to lateral dimension, which makes them highly sensitive towards target gases (Kolmakov et al., 2005).
Biofabrication of zinc oxide nanoparticles by using Lawsonia inermis L. seed extract
Published in Inorganic and Nano-Metal Chemistry, 2023
Khushboo Bhatt, Sonalika Agrawal, Subrat Kumar Pattanayak, Vikas Kumar Jain, Fahmida Khan
Metal oxide nanoparticles are prepared using various traditional methods such as; hydrothermal, chemical and mechanical methods.[17–19] Most of these methods are tedious and using such methods is costly, requires the use of hazardous chemicals. However, green synthesis approaches of preparing metal oxide nanoparticles are environmentally friendly, non-hazardous and less costly than other methods. Green synthesis has become an important synthesis method because of their biocompatibility, devoid of toxic by-products and strong solubility of particles in the aqueous phase. Biosynthesis methods have advantages because of large available plants and phytoconstituents presents therein. The extracts obtained from plants are proven to be an efficient and promising precursor for NPs synthesis. The biomolecules may contain flavonoids, ketonic and phenolic functional groups.[20] These biomolecules are generally used for their dual characteristics; they work as reductant and capping agents during the nanoparticle’s synthesis.
A comprehensive review on coal fly ash and its application in the construction industry
Published in Cogent Engineering, 2022
S. E. Kelechi, Musa Adamu, O. A. U. Uche, I. P. Okokpujie, Yasser E. Ibrahim, I. I. Obianyo
Metal and metal oxides are broadly used as catalysts in different industrial applications. CFA essentially comprises different metal oxides with higher volumes of iron oxides. Hence, usage of CFA in heterogeneous catalysis could provide a financially savvy and environmentally friendly strategy for reusing this waste (Wang et al., 2012). Additionally, because of the higher stability of its chief part, aluminosilicates, CFA could likewise be utilized as catalyst support for different reactions. CFA-supported CaO has been utilized as a recyclable strong base catalyst. Zhang (2014) utilized nitric-acid-initiated CFA as a heterogeneous Fenton-like catalyst for p-nitrophenol evacuation from water. An evacuation pace of 98% was seen in the ideal conditions. Cho et al. (2005) studied the selective catalytic reaction (SCR) utilizing a CFA catalyst. After pre-treating and loading with transition metal components, the outcomes showed that CFA could be sensibly utilized as an SCR catalyst backing to eliminate NO from vent gas. Wang et al. (2012) reported that CFA could be a successful catalyst for gas, fluid, and solid-phase reactions. For example, gas-stage oxidation of volatile organic compounds, aqueous-stage oxidation of organics, solid plastic pyrolysis, and solvent-free organic synthesis. The CFA-supported catalyst showed suitable catalytic activities in hydrocracking and hydrocarbon oxidation. Patil et al. (2020) used CFA as a composite material in reinforced aluminum using a motorized store casting technique and discovered it was suitable for structural application.
Effect of inorganic and organic additives on coal combustion: a review
Published in International Journal of Coal Preparation and Utilization, 2021
Generally, additives play a vital role in coal combustion performance. Some of them improve the combustion performance while some retard the combustion. Metal oxides used are found to be advantageous as they give a catalytic effect. On decomposition, the oxides formed react with the carbon content and improve its combustion efficiency. Ignition temperature and burnout temperature are decreased and thus can be utilized in coal-fired furnaces and boilers. Kinetics study has shown that activation energy can be decreased by few percent. Also to avoid the low-temperature ignition in coal mines or in general, additives like alkali metal and alkali earth metal salts have been used which provided a retarding effect. Wise selection of additives may also help in reducing environmental pollution by lowering harmful gas emission like SO2, NOx, CO, and CO2. Disposal of coal fines has been resolved as it can be utilized with some amount of binder material which will bind the fine together and can be used as reliable fuel for residential and industrial applications. Calorific value is also an important parameter as it decides the UHV of fuel. Very few additives have helped to increase the calorific value up to some extent.