Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide) gemini surfactants as novel corrosion inhibitors for mild steel in formic acid

Abstract

Gemini surfactants, butanediyl 1,4-bis(dimethyl cetylammonium bromide), pentanediyl 1,5 -bis (dimethyl cetylammonium bromide) and hexanediyl 1,6 -bis (dimethyl cetylammonium bromide) from Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide) series were synthesized in laboratory and were characterized by using Nuclear Magnetic Resonance (NMR) spectroscopy. The surfactants were tested as corrosion inhibitors for mild steel in 20% formic acid. The influence of surfactants on mild steel corrosion inhibition was investigated by measuring the corrosion rate of mild steel in their absence and presence by weight loss measurements, solvent analysis of iron ions into the test solution and potentiodynamic polarization measurements. The surface morphology of the corroded steel samples in presence and absence of surfactants was evaluated by using Scanning Electron Microscopy (SEM). The synthesized gemini surfactants performed as excellent corrosion inhibitor, the inhibition efficiency (IE) being in the range of 76.66-97.41%. The IE of surfactants is slightly affected by the spacer length. The IE increased with increase in surfactant concentration and temperature. The adsorption of gemini surfactants on the steel surface was found to obey Langmuir adsorption isotherm. The results of the potentiodynamic polarization studies are consistent with the results of weight loss studies.

Formic Acid

“…For mild steel, the highest corrosion rate is observed around 20% solution concentration, at which the conductivity of the solution is also the highest [39]. Some corrosion inhibitors can give very good protection [40].…”

Study on the Inhibition of Mild Steel Corrosion by Cationic Gemini Surfactant in 1 M HCl

“…The values of adsorption parameters calculated from the Langmuir adsorption isotherm like linear regression coefficient (R 2 ), slope and adsorptive equilibrium constant are given in Table 2 [6] where, 55.55 is the concentration of water in the solution in mole/l and R is universal gas constant. In the present study, the values of ∆G 0 ads ranges from -36.86 to -38.69 kJ/mol, this is lower than -40 kJ/mol but higher than -20 kJ/mol ( Table 2).…”

“…In general, lower the CMC of the surfactant the greater is its tendency to adsorb at the solid surface. In recent years gemini or dimeric surfactants have attracted great attention in corrosion inhibition [6][7][8] . Gemini surfactants, which have two hydrophobic tails connected to the polar hydrophilic head groups through a spacer, have been found more effective in inhibiting corrosion as compared to conventional surfactants.…”

The inhibitory action of Bauhinia purpurea extracts on the corrosion of carbon steel in sulfuric acid medium

“…In this context, the search for corrosion inhibitors in acidic media to protect metallic surfaces has established the natural products as a rich and promising source. The protective efficiency appears to increase with the presence of oxygen, nitrogen, sulphur and π electrons in the organic compounds [1][2][3][4] . Apparently, the inhibition efficiency is linked to the polar functions that act as the reaction center for the adsorption process 5 .…”