China
Africa
Explore chapters and articles related to this topic
Nanosensor Laboratory
Published in Vinod Kumar Khanna, Nanosensors, 2021
This is the simplest etching technology, using a container with a liquid solution that will dissolve the material in question. Buffered HF, a mixture of a buffering agent, such as ammonium fluoride (NH4F), and hydrofluoric acid (HF), is commonly used for etching silicon dioxide selectively, whereas orthophosphoric acid (H3PO4)-based compositions are employed for aluminum etching. An etchant for gold is potassium iodide (KI) in iodine (I2). Silicon etchants are mixtures of HF, HNO3, and acetic acid (CH3COOH).
Water/Wastewater Math Operations
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Fluorosilicic acid (H2SiF6), also known as hydrofluorosilicic or silicofluoric acid, is a 20–35% aqueous solution with a formula weight of 144.08. It is a straw-colored, transparent, fuming, corrosive liquid having a pungent odor and an irritating action on the skin. Solutions of 20–35% fluorosilicic acid exhibit a low pH (1.2), and at a concentration of 1 ppm can slightly depress the pH of poorly buffered potable waters. It must be handled with great care because it will cause a “delayed burn” on skin tissue. The specific gravity and density of fluorosilicic acid are given in Table 5.6. Approximately 46 pounds (4.4 gal) of 23% acid are required to add 1 ppm of fluoride to 1 million gallons of water. Two different processes, resulting in products with differing characteristics manufacture fluorosilicic acid. The largest production of the acid is a by-product of phosphate fertilizer manufacture. Phosphate rock is ground up and treated with sulfuric acid, forming a gas by-product. Hydrofluoric acid (HF) is an extremely corrosive material. Its presence in fluorosilicic acid, whether from intentional addition, i.e., and “fortified” acid or from normal production processes demands careful handling.
Development of a novel biocollector for flotation of low grade graphite ore
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Vasumathi Nallusamy, Chennakesavulu Kattela, Cassandra Austen Immanuel, Ajita Kumari, Jayasankar Kalidoss, Sreejakumari Sukumaran Suseelamma, Vijayakumar Tadiparthi Venkata, Gopalkrishna Sirigeri Jois
Graphite has a unique role in many industrial applications due to its various physical and chemical characteristics, namely, good thermal and electrical conductivity, lubrication properties, resistance to chemicals, and temperature-change resistance. Natural graphite is available in three commercial varieties such as crystalline flake, microcrystalline, or amorphous and crystalline vein or lump (Crossley 2000). On depletion of high-grade graphite ores, the low-grade and complex ores are now the available source of raw materials which requires an economical and versatile process of beneficiation. Hydrometallurgical purification is one of the established methodologies for purification, which comprises (i) flotation, (ii) acid-base, and (iii) hydrofluoric-acid (HF in water) techniques. Among these, flotation is the most cost-effective process, using the natural floatability of graphite for enhancing beneficiation (Jara et al. 2019).
Effect of hydrochloric acid and hydrofluoric acid treatment on the morphology, structure and gamma permeability of 2D MXene Ti3C2Tx electrodes
Published in Canadian Metallurgical Quarterly, 2022
Mesut Ramazan Ekici, Emre Tabar, Ahmet Atasoy, Emrah Bulut, Gamze Hoşgör
The aim of this work is twofold. Firstly, we focus on the effect of etching time with hydrofluoric acid. MXene phase, namely Ti3C2Tx powder, was subjected to hydrofluoric acid (HF) at room temperature for 2, 16, and 48 h. Then, the structural changes in the materials were analysed by SEM, FE-SEM, TEM, and using XRD. Batteries have the potential to be used in nuclear power plants and space exploration, where they will be exposed to gamma radiation. Therefore, it is important to determine their sensitivity to gamma radiation. Thus, secondly, the Gamma radiation absorption properties of these materials were examined with the typical experimental setup equipped with 3 × 3 NAI(Tl) detector. The effect of the different mixture times on the Gamma radiation absorption properties was also studied. To the best of our knowledge, the gamma radiation shielding characteristic of these materials has not been investigated neither theoretically nor experimentally.
The influence of a dielectric spacer layer on the morphological, optical and electrical properties of self-dewetted silver nanoparticles
Published in Phase Transitions, 2021
Leila Manai, Béchir Dridi Rezgui, Damien Barakel, Philippe Torchio, Olivier Palais, Olfa Messaoudi, Arwa Azhary, Feriel Bouhjar, Brahim Bessais
The process of cell fabrication of the self-assembled Ag-NPs/c-Si structure is carried out through several consecutive steps. Mono-crystalline silicon produced by Czochralski, doped boron (B) with the orientation (100) is used in this work. Prior to doping, silicon wafers were initially ultra-sonicated sequentially at 40°C in acetone, isopropanol and deionized water for 10 min in order to remove organic and inorganic impurities. The cleaning continues with an etching step for 3 min in diluted (5%) hydrofluoric acid solution that results in flat silicon wafer surface. For achieving a p-n junction, p-type silicon wafer is undergo to the new dopant phosphorus (P) atoms which can be diffused into the material through concentration gradient. The process is performed by thermal physical vapor deposition system at high temperature. Liquid phosphoryl chloride (POCl3) is transported to silicon wafers via nitrogen carrier gas in the furnace at 930°C. Oxygen flow (O2) is used to help the creation of n-type layer according to the equations: