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Humidity Sensor Based on Alum–Fly Ash Composite
Published in Amit Sachdeva, Pramod Kumar Singh, Hee Woo Rhee, Composite Materials, 2021
Amit Sachdeva, Shri Prakash Pandey, Pramod K. Singh
The most common alum is the double sulfate of potassium and aluminum, K2Al2(SO4)4.24H2O, a white crystalline powder that is readily soluble in water. It is used in curing animal skins. Other alums are used in papermaking and to fix dyes in the textile industry. The raw material of manufacture of common alums is alum rock, composed chiefly of alunite or alum stone. Alum is also made from alum shale, which is either allowed to decompose by exposure, or roasted. During the process, free sulfuric acid is formed, which acts upon the clay, producing aluminum sulfate, which is then dissolved out. Potassium sulfate or ammonium sulfate is added to the solution to produce potash alum or ammonia alum.
Phase-Change Materials
Published in George A. Lane, Solar Heat Storage: Latent Heat Materials, 1986
Ammonium alum causes slight acute or chronic irritation from local contact. Inhalation can cause slight chronic irritation. Ingestion could cause moderate acute toxicity. Acute and chronic systemic hazards are not documented; however, the material is used as a general purpose food additive.26
Extraction equilibrium conditions of beryllium and aluminium from a beryl ore for optimal industrial beryllium compound production
Published in Canadian Metallurgical Quarterly, 2019
Alafara A. Baba, Daud T. Olaoluwa, Ayo F. Balogun, Abdullah S. Ibrahim, Fausat T. Olasinde, Folahan A. Adekola, Malay K. Ghosh
Beryllium metal, alloys and some compounds of beryllium especially beryllium sulphate have been used widely in industry for many decades particularly in specific areas of nuclear technology. Their ability to reflect neutrons and its efficiency in the production of neutrons when exposed to alpha emitters has led to its use in nuclear reactors and nuclear weapons [1,2]. These applications have the impetus to the development in its extraction and manufacturing processes through different routes. The production of beryllium from beryl ore is a complicated process because of the inert nature of the mineral with mineral acids under the normal conditions of temperature and pressure. Therefore, leaching of beryllium from the mineral is generally carried out by fusion with potassium hydroxide and potassium carbonate mixture, followed by quenching in cold water to destroy the original crystal structure of beryl [3]. The soluble alkali salts are dissolved in water and the glassy beryl is reheated, ground and dissolved with a sulphuric acid solution [4]. This solution contains mainly aluminium together with beryllium and other impurities. To this solution, ammonia liquor is added to precipitate beryllium hydroxide and bring most of the ammonium alum in solution.
Phase change materials development from salt hydrate for application as secondary refrigerant in air-conditioning systems
Published in Science and Technology for the Built Environment, 2018
Muhammad Irsyad, Aryadi Suwono, Yuli Setyo Indartono, Ari Darmawan Pasek, Muhammad Akbar Pradipta
From the previous calculations, overall heat transfer coefficient for salt hydrate from is higher when the system employs water, as shown in Figure 10. The energy released by hot fluid is used as the heat transfer parameter, in which the fluid is water. As a comparison, heat transfer in cold fluid encounters constraint as the formulated solid mass concentration is difficult to measure. Hot fluid heat transfer increases when the salt hydrate is employed. The average increase of heat transfer is 18.62% of CaCl2 compound and 13.9% of Na2HPO4 compound. This trend supports the previous study on ammonium alum hydrate slurry (Suzuki et al. 2013), and trimethylolethane (Indartono et al. 2006).
Structural and optical properties of aluminum nitride nano powder prepared from tris (N,N dimethyl-ethylenediamine)AlCl3 precursor
Published in Journal of Coordination Chemistry, 2023
Himanshi Chaurasia, Santosh K. Tripathi, Kamlesh Bilgaiyan, Akhilesh Pandey, N. Eswara Prasad
Numerous techniques have been used to prepare AlN materials e.g. direct nitridation of aluminum metal, carbothermal reduction (CR), gas-reduction nitridation (GRN), vapor-liquid-solid (VLS), atomic layer deposition (ALD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), etc. [7–11]. Recently, researchers have reported the preparation of aluminum nitride using precursors with many approaches [12–14]. Lu et al. prepared AlN powder using AACH precursor which was prepared by the reaction of ammonium alum and ammonium hydrogen carbonate by precipitation at 1400–1550 °C [15]. Wu et al. [16] reported AlN powder using sodium fluoride-assisted carbothermal combustion at 1300 °C. Qin et al. [17, 18] prepared AlN by alumina and carbon (Al2O3+C) using aluminum nitrate (Al(NO3)3·9H2O), urea (CO(NH2)2), and glucose (C6H12O6·H2O) at 1400–1500 °C. Likewise, Kato et al. [19] synthesized AlN powder using ammonium chloride and aluminum whereas high temperature preparation (at 1574 °C) of AlN powder using NH3 and hydrazine (N2H4) has been reported by Hermawan et al. [20]. Cheng et al. [21] described the formation of AlN powder from polymeric metal-urea precursor. The preparation is highly challenging and often requires high deposition temperature or use of acids, corrosive and toxic gases which possess health hazards as well as environmental risks. Also the high temperature deposition generates cracks and defects. Hence non-toxic, environment friendly, low-temperature, and easy process for high purity AlN are desired for semiconductor industries to cater to the need for devices based on AlN.