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Hydrogen Production by Catalytic Reforming Process
Published in Sonil Nanda, Prakash K. Sarangi, Biohydrogen, 2022
Chandramani Rai, Prabu Vairakannu
The steam reforming process using various kinds of feedstock and catalyst produces hydrogen. Methane, ethane, acetic acid, methanol, ethanol, methane, ethane, tar are the potential feedstocks for hydrogen production through the catalytic reforming process. Ethanol exhibited a good reforming tendency with steam for hydrogen generation using nickel-based catalysts. Dry reforming using CO2 and methane could be a viable option. However, it requires high operating temperatures. The partial oxidation method can be a better option as this process generates its required energy, but the formation of hotspots deteriorates the activity of catalysts. Tri-reforming and chemical looping reforming are the emerging technologies to produce hydrogen. Chemical looping reforming technology can produce ultrapure hydrogen directly from the steam without any contamination from other gasses. However, the integration of three reactors and the circulation of metal oxides among them and heat balance between the reactors are the major challenges for hydrogen production. Other alternate technologies such as pyrolysis, gasification, and water splitting, etc., can be used to produce hydrogen. In all the processes, noble metals or transition metals are the catalysts; noble metals are highly efficient catalysts as it resists the deposition of carbon; however, it is expensive. Alternatively, transition metals are low cost but it gets deactivate with carbon deposition. Hence, appropriate catalyst development is important for the efficient conversion of feedstocks to hydrogen.
Macrocyclic Receptors for Precious Metal Ions
Published in Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney, Macrocyclic Receptors for Environmental and Biosensing Applications, 2022
Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney
The noble metal gold is greatly in demand for its use in various fields, including the jewellery sector, electronics, catalysts, aerospace and spacecraft industry and medicines. The extensive use of gold in modern electronic circuitry has most promisingly transformed e-waste in worldwide assets. Due to limited natural resources of gold in nature and to meet the increasing demand for gold, it is imperative that the secondary sources of gold, such as e-waste be tapped for efficient recovery of gold. However, it is a challenge to selectively recycle gold ions from e-waste as gold is usually present along with other metals, for example, copper, zinc and nickel and its concentration in the leaching solutions are very low (Xu et al. 2019).
Introduction of Plasmons and Plasmonics
Published in Sanjeev Kumar Raghuwanshi, Santosh Kumar, Yadvendra Singh, 2D Materials for Surface Plasmon Resonance-based Sensors, 2021
Sanjeev Kumar Raghuwanshi, Santosh Kumar, Yadvendra Singh
The joint excitation of a surface plasmon and a photon is called Surface Plasmon Polariton (SPP). However, excitation of a Surface Plasmon would not be possible unless a specific condition fulfills both energy and momentum conservations. In generalized terms, the metal-insulator or metal-dielectric interfaces are the normally chosen metals, which are noble metals. Most of the noble metals, unlike most base metals, have good corrosion resistance. Hence, they do not suffer from oxidation problems. However, noble metals are very precious due to their mining process under earth crust. Some of the noble metals generally found in Earth’s crust are ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold. For the study of surface plasmonics, optical properties of noble metals must be studied first. For this, we have to study many models. Two of them are listed below in detail.
Application of black cumin (Nigella sativa L.) seeds for the removal of metal ions and methylene blue from aqueous solutions
Published in Cogent Engineering, 2022
Patience Mapule Thabede, Ntaote David Shooto
Dyes and waste products from mining, tanneries, metal plating facilities, and industries that deal with pesticides, batteries, industries, and paper are harmful to the environment and human health (Kausar et al., 2018). For instance, mining activities generate large quantities of wastes laden with both harmful and hazardous metals ions as well as some noble metals such as Pb, Cd, Cr, Ag, As, Hg, Zn, Cu, Ni, Se, Co, Fe, I, Mn, Mo, and Zn, that are released into the environment and pollute the ecosystem (Ebenebe et al., 2017). Since toxic metals are soluble in aquatic environments, they can be absorbed by living organisms (Barakat, 2011). Large concentrations of these toxic metals may accumulate in the human body when enter the food chain. Unlike organic contaminants, toxic metals ions are not biodegradable and are known to be carcinogenic and poisonous (Fu. & Wang, 2011). Therefore, contaminated wastewater that contain toxic metal ions must be treated prior to its discharge to the environment. Methylene blue (MB) is a cationic dye used as an indicator, a textile dye, and in other industries (Hevira et al., 2021; Iwuozor et al., 2021). Owing to its many uses, MB is a common pollutant in the environment and has negative ecotoxicological implications (Ahmadi & Igwegbe, 2020; Igwegbe et al., 2019).
A Review on the Recovery of Noble Metals from Anode Slimes
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Wei Dong Xing, Seong Ho Sohn, Man Seung Lee
Leaching of the enriched residues containing noble metals is an important step for the recovery of noble metals. The enriched residues of lead, tin, and zinc anode slimes generally contain only either gold or silver among the noble metals. Therefore, leaching of these enriched residues with nitric acid solution would lead to the recovery of silver metal, while dissolving most of the base metals (Li et al. 2006; Harangi et al. 2015). In contrast, other noble metals are present in the enriched residues of copper anode slimes, which makes the separation process complicated. Therefore, leaching of noble metals from the enriched residues of copper anode slimes after pretreatments is considered in the following sections. Leaching reagents such as cyanide, thiourea, thiosulfate, and halide have been employed for this purpose and thus the characteristics of these systems are reviewed.
Green synthesis and characterization of the graphene oxide derocated with Pd, Ag
Published in Inorganic and Nano-Metal Chemistry, 2022
Noble metals have unique catalytic properties and are widely used in catalytic industry. Noble metals are also commonly used as anode catalytic materials in fuel cells. Noble metals have high melting point, conductivity, corrosion resistance and stability, and they are excellent catalysts. However, there are still some defects and shortcomings in using precious metals only. It mainly includes that the catalytic activity can not meet the commercial application for the time being and the price of precious metals is expensive. Therefore, when noble metals and GO are compounded, the synergistic effect between oxides and noble metals can be used to reduce the use of catalysts, which is a promising way of noble metal modification.