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Terpenes and Terpenoids
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Acetic acid comes from vinegar and is a descaling agent and photographic film inhibitor; it is used in electroplating, as a solvent for paints; it is used in the production of vinyl acetate, as a chemical reagent, it is used in production of polyethylene phosphate, and as a photolab anhydrate. Further transformations of the compound result in the true terpenes and terpenoids. The true terpenes are grouped according to the specific number of isoprene units (C5H8) in a molecule; for example, monoterpenes (C10H16) contain two units; sesquiterpenes (C15H24) contain three; diterpenes (C20H32),75 triterpenes (C30H48),76 and tetraterpenes (C40H64). Polyterpenes such as rubber and gutta-percha (used in root canals for teeth repairs contain 1000–5000 isoprene units joined in a long chain.
Toward the development of an innovative descaling and corrosion inhibiting solutions to protect mild steel equipment: an experimental and theoretical approach
Published in Chemical Engineering Communications, 2020
Hanane Bidi, Mohamed Ebn Touhami, Yacine Baymou, Ill-Min Chung, Hassane Lgaz, Saman Zehra
The formation of mineral scales on the inner wall of the metal tube is a persistent problem in many different industrial sectors (Boulahlib-Bendaoud et al., 2012; Aidoud et al., 2017). Calcium carbonate is one of the major constituents in scale, especially in hydraulic installations, and cooling circuits buried in the soil. Indeed, the scaling phenomenon often leads to a series of problems such as pipe blockage, increase in energy consumption, concealment of corrosion, and unscheduled equipment shutdown (Boulahlib-Bendaoud et al., 2012; Yu et al., 2016). Acid solutions which are being used extensively in various industrial acid cleaning applications are hydrochloric, sulfamic, sulfuric, and citric acids (Anuradha et al., 2007; Morad, 2008; Abboud et al., 2009; Tao et al., 2009; Amin and Ibrahim, 2011; Oguzie et al., 2014; Al-Moubaraki, 2015; Arukalam et al., 2015). While the importance of hydrochloric acid as efficient descaling agent for iron alloys is well-established, but its use may produce strong corrosion problems such as pitting and/or chloride-induced stress corrosion cracking (Morad, 2008). Therefore, suggestions have been made to replace hydrochloric acid by the sulfamic acid for the removal of the scales. Although several advantages have been attributed to the sulfamic acid – especially its remarkable effectiveness for dissolving iron oxides and variety of water-formed scales, its stability in the solid state, the non-stability of the aqueous solutions of sulfamic acid, and its slower action still raises some questions. Thus, a formulation that provides an efficient descaling rate and lower corrosion effect is highly needed. In this regard, the addition of the corrosion inhibitor and a less corrosive acid such as perchloric acid to the sulfamic acid solution can remarkably increase the scaling performance and can keep the surface of metal intact during the cleaning process (El Azhar et al., 2002; Lebrini et al., 2005). Throughout the last years, some efforts have been devoted to the study of the corrosion inhibition of steel alloys in sulfamic and perchloric acids (Lebrini et al., 2008; Morad, 2008). However, for unknown reasons, there is still lack of comprehensive studies on metals corrosion inhibition in sulfamic and perchloric acids.