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Abstract
A novel series of cationic surfactants containing Schiff base groups were synthesized by condensation of fatty amines namely: dodecyl, tetradecyl, hexadecyl and octadecyl amine and 4-diethyl aminobenzaldehyde. The chemical structures of these surfactants were confirmed using elemental analysis, FTIR spectra, ^sup 1^H-NMR and atomic absorption spectroscopy. Surface properties of the synthesized compounds were determined using surface tension techniques. The results of the surface tension measurements showed good surface behaviors of these compounds in their aqueous solutions. The surface activities were found to be greatly influenced by the chemical structures of the synthesized compounds. The synthesized cationic Schiff bases were evaluated as corrosion inhibitors for carbon steel in different acidic media (HCl and H^sub 2^SO^sub 4^) at different doses (400, 200, 100, 50, 25 ppm). The corrosion inhibition efficiencies of these inhibitors were calculated using the corrosion rates of the carbon steel in the studied media and found in the acceptable range of the commercially used inhibitors. Also the chemical structure of these inhibitors was found of great influence on their inhibiting efficiency.
Keywords Cationic Schiff base * Surface activity * Adsorption * Micellization * Emulsification * Corrosion rate * Corrosion inhibition efficiency
Introduction
Schiff bases are one of the important classes of organic compounds which have many interesting properties and extensive applications in biology and materials science [1-3]. The Langmuir-Blodgett films of amphiphilic Schiff base compounds have been investigated and their interesting features revealed [4, 5]. The main properties studied focused on the coordination with transition metal ions, and some organized molecular films of these Schiff base derivatives have been reported. Using the LangmuirBlodgett technique, it is convenient to form ordered layer structures by the transferring monolayers from water surface-to-solid substrate. This ordered deposition offers potentially greater control over molecular orientation and inter-molecular packing for these materials, which could lead to more and more creations of new types of thin-film devices especially in the field of electronics and optics. Research work on the behavior of Langmuir and LB films has been attracting increasing attention in recent years. The formation of bilayer membranes from single-chain amphiphiles in dilute aqueous solution is mainly determined by the balance between the interactions among the hydrophobic tails and that among the hydrophilic head groups and the molecular geometry...