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Infrared Thermography in Convective Heat Transfer
Published in Wen-Jei Yang, Handbook of Flow Visualization, 2018
Giovanni Maria Carlomagno, Luigi de Luca
Germanium’s primary transmission range is from 2 to 15 µm, making it useful for IR laser applications, particularly in the LW band. It is opaque in the visible region, and because of a high surface reflectivity of 36% (related to its high refractive index, which is greater than 4), Ge should have an antireflective (AR) coating. Silicon (Si) is similar to germanium but with greater resistance to mechanical and thermal shocks. Its use in the LW region requires extensive calibration due to the strong variation of the transmission coefficient. Arsenic trisulfide (As2S3) has a transmission range from 0.5 to 13 µm, but is quite soft and brittle. Its coefficient of thermal expansion is very similar to that of aluminum. Zinc selenide (ZnSe), with a transmission range from 0.58 to 15 µm, is useful for IR applications in both SW and LW bands, permitting visual alignment. An AR coating is required to decrease the 17% single-surface reflection loss. Calcium fluoride (CaF2) [30] and magnesium fluoride (MgF2) [29] have excellent transmission over a broad spectral range. The former is usable from 0.15 to 9 µm, and the latter from 0.11 to 7.5 pm. Both of these materials are slightly water soluble. Their low index of refraction allows them to be used without AR coatings; MgF2 is more durable than CaF2, and both are sensitive to thermal shock. Sapphire (A12O3) [28], also known as 9752 IR glass, has an extremely hard surface, is chemically inert, and is insoluble except at very high temperatures. It exhibits high transmittance (all the way from 0.15 to 6 µm), which makes it useful in the SW band and allows visual alignment. Because of its great strength, the sapphire window can safely be made much thinner than windows of other material. The sapphire window is therefore useful even at wavelengths very close to its transmission limits. Because of sapphire’s exceptionally high thermal conductivity, thin windows made of it can be effectively cooled by forced air or other methods.
Improving removal rate and efficiency of As(V) by sulfide from strongly acidic wastewater in a modified photochemical reactor
Published in Environmental Technology, 2022
Linghao Kong, Yuchen Wang, Xingyun Hu, Xianjia Peng, Zhilin Xia, Jianbing Wang
A large quantity of strongly acidic wastewater (waste acid) with high arsenic concentration is produced by mineral processing, sulfuric acid production, and nonferrous metal smelting industries, etc. The treatment of strongly acidic wastewater remained difficult because of the high concentration of arsenic and acid, and the improper treatment may lead to serious environmental pollution. Recently, the treatment of strongly acidic wastewater has attracted extensive attention [1–5]. The removal of arsenic by sulfide (S(-II)) is a promising method, by which arsenic could be in situ removed as arsenic trisulfide (As2S3) precipitate with high purity and a small amount [6, 7] compared with the method of neutralization using Ca(OH)2 and the coprecipitation of arsenic with ferric iron [8–10]. The sulfuration method has become a potential arsenic treatment technology, which could facilitate the recycling of arsenic and acid.