Gemini cationic surfactant of 1, 3-bis (dodecyl dimethyl ammonium chloride) propane as a novel excellent inhibitor for the corrosion of cold rolled steel in HCl solution.

Gemini surfactants have become the research focus of novel excellent inhibitors because of their special structure (two amphiphilic moieties covalently connected at head group by a spacer) and excellent surface properties. It is proved by theoretical calculations that 1, 3-bis (dodecyl dimethyl ammonium chloride) propane (BDDACP) molecules can perform electron transfer with Fe (110). And it has a small fraction free volume, thus greatly reducing the diffusion and migration degree of corrosive particles. The potentiodynamic polarization curve showed that coefficients of cathodic and anodic reaction less than 1 and polarization resistance increased to 1602.9 Ω cm after added BDDACP, confirming that BDDACP significantly inhibited the corrosion reaction by occupying the active site. The electrochemical impedance spectrum of imperfect semi-circle shows that the system resistance increases and double layer capacitance after added BDDACP. Weight loss tests also confirmed that BDDACP forms protective film by occupying the active sites on steel surface, and the maximum inhibition efficiency is 92 %. Comparison of the microscopic morphology showed that steel surface roughness was significantly reduced after added BDDACP. The results of time-of-flight secondary ion mass spectrometry show that steel surface contains some elements from BDDACP, which confirms the adsorption of BDDACP on steel surface.