Synthesis of Selected Vinylimidazolium Ionic Liquids and Their Effectiveness as Corrosion Inhibitors for Carbon Steel in Aqueous Sulfuric Acid

Abstract

Five imidazolium-type ionic liquids, containing both N1 unsaturated and N3 long alkyl saturated chains as cations and bromide as anion (IL1–IL5), were obtained by conventional and microwave synthesis. Compounds were tested in aqueous 1 M H2SO4 as corrosion inhibitors for carbon steel. Weight loss and polarization curves indicated that inhibition efficiency increased with concentration, which turns out to be dependent on alkyl chain size linked to N3 (IL4 > IL3 > IL1 > IL2 > IL5). The relatively high inhibitory properties (88–95%) displayed by IL4 within 25–40 °C were ascribed to a chemisorption process that involved the following: the adsorption of protonated imidazolium molecules on both the anodic and cathodic sites, the latter in competition with hydrogen ions to mitigate hydrogen evolution; and also the formation of π bond with iron by the CN group from imidazolium ring (this way inhibitor produced more than one center of adsorption action). Surface analysis indicated a considerable reduction of corrosion products after the addition of IL4.

Some Phthalocyanine and Naphthalocyanine Derivatives as Corrosion Inhibitors for Aluminium in Acidic Medium: Experimental, Quantum Chemical Calculations, QSAR Studies and Synergistic Effect of Iodide Ions

“…The dissolution of Al has been reported to be more rapid in acidic solutions containing chloride or fluoride ions than in the near-neutral solutions [4][5][6]. Corrosion inhibitors offer an efficient, a convenient and relatively cheap method of controlling corrosion of metals in various aggressive media [3,[7][8][9][10][11]. For this reason, a number of studies have been reported on the use of corrosion inhibitors to mitigate the corrosion of Al in chloride solutions [12][13][14].…”

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Abstract:The effects of seven macrocyclic compounds comprising four phthalocyanines (Pcs) namely 1,4,8,11,15,18,22,2,3,9,10,16,17,23,2,9,16, and 29H,31H-phthalocyanine (Pc4), and three naphthalocyanines namely 5,9,14,18,23,27,32,2,11,20, properties of the compounds were also investigated. All the studied compounds showed appreciable inhibition efficiencies, which decrease with increasing temperature from 30 °C to 70 °C.

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Ionic Liquids as Electrodeposition Additives and Corrosion Inhibitors

“…There are various organic inhibitors that tend to decrease the corrosion rate of steel and iron in acidic solutions [28,[83][84][85][86]. ILs with imidazolium [87][88][89][90][91][92] and pyridinium cations [93,94] have showed excellent corrosion inhibition performance on mild steel in an acidic environment. We have irst investigated the acid corrosion inhibition process of mild steel [2] 4 .…”

Environmentally Friendly Corrosion Inhibitors

“…They offer novel physical and chemical properties like low toxicity, high chemical stability, low vapour pressure and high electrical conductivity [152][153][154][155][156][157].…”