China
Africa
Explore chapters and articles related to this topic
TL/OSL Properties of Calcium Oxide Nanophosphor
Published in Odireleng Martin Ntwaeaborwa, Luminescent Nanomaterials, 2022
K.R. Nagabhushana, Sonia Hatsue Tatumi, D. Prakash
Inorganic oxides are binary compounds of oxygen with an element and classified into acidic or basic oxide based on their characteristics. Inorganic oxides can be prepared by direct heating of element with oxygen, the reaction of oxygen with compounds at high temperatures, oxidation of metals and non-metals with nitric acid [7]. Inorganic materials are ionic compounds, consisting of cation and anion linked by ionic bonding and they are electrically neutral. The ions are defined by their oxidation state, and their ease of creation can be inferred from the ionization potential (cations) and/or from the electron affinity (anions) of the parent elements. The inorganic oxides are characterized by high melting point. Inorganic salts are typically poor electric and thermal conductors in the solid state.
Synthesis of Nanomaterials for Drug Delivery
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials II, 2021
Hemant K. S. Yadav, Shahnaz Usman, Karyman Ahmed Fawzy Ghanem, Rayisa Beevi
Pulsed laser ablation technique is a thin film deposition technique used in the synthesis of a wide range of nanomaterials. The basic principle of this technique involves evaporating the sample material using photons, which are emitted by a short-pulsed high energy laser beam in a chamber filled with reagent gas.[37] The evaporated particles are condensed over a support, forming nanoparticles. As the vapor of the sample material travel from the evaporation source to the substrate, it interacts with the gas particles producing the required compound. For instance, if oxygen gas is used, then oxides are produced.[37,38] However, nitrides are produced if ammonia or nitrogen gas are used, whereas carbides are formed in case of using methane. The size distribution of the formed nanomaterial as well as its elemental composition depends on the power of the laser pulse, temperature, and the gas composition used in the chamber.[38]
Time, Temperature, and Environmental Effects on Properties
Published in David W. Richerson, William E. Lee, Modern Ceramic Engineering, 2018
David W. Richerson, William E. Lee
Decomposition reactions are very important in the processing of oxide ceramics and refractories. The oxides are usually derived from metal salts such as carbonates, hydroxides, nitrates, sulfates, acetates, oxalates, or alkoxides. These salts are either naturally occurring raw materials or the results of chemical refining operations. They are used as a portion of the raw materials in the fabrication of glass, refractories, and a wide variety of ceramic products. The powders decompose at low to intermediate temperatures to produce a high surface area and reactive solid oxide plus a gas in a process called calcination, described further in Chapter 12. Heating rates and decomposition temperatures must be carefully controlled to avoid breaking unfired ceramic components containing metal salts during processing as a result of the too rapid evolution of the reactant gas. It is also important that complete decomposition occurs before melting or densification of the part begins.
The transformation of high-viscosity oil of carbonate rock in the presence of CO[AcAc]3 catalyst in a vapor-air medium
Published in Petroleum Science and Technology, 2018
A. Nosova, S. Petrov, A. Safiulina, G. P. Kayukova, N. Bashkirceva
Intrastratal oxidation requires the formation temperature in the range 250–350°C, which promotes reactions of low-temperature oxidation of petroleum hydrocarbons. The high temperature in the reservoir can be achieved by using method of injection of binary mixtures or thermal steam technology. Initiation of reactions of low-temperature oxidation in the presence of air oxygen, is also possible with the help of effective heterogeneous or homogeneous catalysts (Muraza and Galadima 2015; Wang et al. 2010; Hao et al. 2017; Moskovskaya et al. 2015). Homogeneous catalysis is one of the most effective methods of improving the selectivity of radical-chain reactions as homogeneous catalysts are able to have an impact on the individual, elementary steps of the oxidation process. Oxides of metals are usually used as catalysts in oxidation processes. The formation of radicals occurs by the interaction of hydrocarbons with an oxygen molecule. A vivid example of homogeneous catalysts of oxidation reactions are cobalt compounds. They are responsible for the formation of numerous chemical products containing oxygen (Rodionova et al. 2012; Sasi, Prathapachandra Kurup, and Suresh 2007). Cobalt-containing catalytic systems can oxidize saturated hydrocarbons, convert them into a mixture of carboxylic acids, aldehydes and esters that can destroy the carbonate reservoir (Franco, Zabala, and Cortés 2017).
Study of adsorption characteristics of long chain alkyl amine and petroleum sulfonate on silicates by electrokinetic potential, microflotation, FTIR, and AFM analyses
Published in Particulate Science and Technology, 2019
Savaş Özün, M. Ümit Atalay, Şahinde Demirci
When mineral particles are brought into contact with aqueous solutions, ions on the mineral surfaces chemically bond to water molecules as a consequence of surface complexation. The hydroxyl groups on the mineral surfaces form pH base negatively or positively charged surface species through protonation or deprotonation (Churchill, Teng, and Hazen 2004). The hydrous oxides, such as Si–O and Al–O, display amphoteric structure which accepts or donates proton in aqueous solutions. The surface reactions where central metal ion is Si or Al can be given as below;
Prospects of novel heterogeneous base catalysts and nanocatalysts in achieving sustainable biodiesel production
Published in International Journal of Green Energy, 2023
Dhnyaneshwar Raising Rathod, Sandesh Suresh Karkal, Akil Salim Jamadar, Aliaa M.A. Hashem, P. V Suresh, S.S Mamatha, Tanaji G. Kudre
Heterogeneous metal oxide nanocatalysts for biodiesel production have recently received considerable attention. Specific surface area, active site concentration, pore volume, and pore size are all factors that influence catalyst efficiency. Metal oxides are generally made up of positive metal ions (cations) that have Lewis’s acidity or act as electron acceptors and negative oxygen ions (anions) that act as proton acceptors and thus act as Brønsted bases (Refaat 2011). The different metal oxide catalysts employed for biodiesel production are described below.