The Gemini Cationic Surfactant Inhibition Behavior

Gemini surafetant with a moleeular structure is a new generation of surafetnat, which is made up of two idnetical amphiphilic moieties covalently connected at the level of the head gropus by a spacer group. By this way, the separation bewteen the polar head groups wihtin Gemini surfactant is srtongly decreased when they aggregate and thus the surface activity greatly is greatly enhanced.The research on Gemini surfactants began to study from the 70s in last century abroad, which began to study from the late 90s in last century. Currently, the focuses of research on Gemini surfactant is foamability, conductivity and other properties. And most researcher regard A3 steel as substrate. But research on spacer of Gemini surfatants is little. Therefore, We will research Gemini Cationic Inhibitors' corrosion behavion Asia alkyl 1,2-bis (dodecyl)-ethyl bromide) (12-s-12 (Et) (s=3,4,5,6) on the 2Cr13 steel surfaces in in 1M hydrochloride acid 25℃by weight loss and electrochemical polarization technology, studied their inhibition mechanism by surface tension testing technology in combination and electrochemical methods. The main conclusions are as follows:1) We critical miccelle concentration(CMC) values, the surface tension at their CMC(γcm) values, the efficiency of decreasing the surface tention(C2o) Calculated adsorption capacityΓ∞, Minimum surface area Amin, and Maximum performanceπcmc of the Gemini surfactants. Result show that Gemini surfactants have much lower CMC and stronger surface activity comparing with the corresponding common surfactants.2) We researched Gemini Cationic Inhibitors'corrosion behavion Asia alkyl 1,2-bis (dodecyl)-ethyl bromide) (12-s-12 (Et) (s=3,4, 5,6) on the 2Crl3 steel surfaces in 1M hydrochloride acid 25℃by weight loss and electrochemical polarization technology. The experimental results show that the adsorption of Gemini surfac--tants on the steel surface, which conforms to Langmiur's isothermal adsorption, is the main reason of corrosion inhibition for the steel in hydrochloride acid. Its corrosion inhibition efficiency increases with the dosage and the spacer length increasing, when the surfactant con-centration close to its critical micelle concentration reached maximum, and its spacer length of the Gemini surfactant more longer, its critical micelle concentration more lower.3) We researched Gemini Cationic Inhibitors'corrosion behavion Asia alkyl 1,2-bis (dodecyl)-ethyl bromide) (12-s-12 (Et) (s=3,4, 5,6) on the 2Cr13 steel surfaces in 1M hydrochloride acid 25℃by weight loss and electrochemical polarization technology. The experimental results indicate that:the Gemini surfactants on A3 steel in 25℃,1MHCl had strong inhibitions. Especially 12-5,6-12 Gemini surfactants, they had stronger inhibition, the concentration of inhibition efficiency reached 85% in lower concentration, and its spacer length of the Gemini surfactant more longer, its critical micelle concentration more lower.4) The corrosion rate of 2Crl3 steel in the H2S/CO2-saturated medium exponentially reduced with the increase of surfactants dosage at 50℃,70℃,90℃, after adding 12-s-12e Gemini surfactants, which indicated that the Gemini surfactants had good inhibition performance. The inhibition performance of Gemini surfactants was better at high temperature than that at low temperature, but when increased the temperature from 70℃to 90℃, the efficiency of surfactants became flatten, because the temperature rise, Gemini surfactant micelle aggregation number decreased5) Compared the polarization curve of 2Cr13 steel and A3 steel, the corrosion rate of 2Cr13 steel and A3 steel in 1M hydrochloride acid 25℃is greatly diffrent because their composition and structure, if we add the 12-3,4-12 Gemini surfactant, they were similar, but when we add the 12-5,6-12 Gemini surfactant, the concentration of A3 steel's inhibition efficiency reached 85% in lower concentration 10-6 mol·L-1),and the concentration of 2Cr13 steel's inhibition efficiency is diffrent. Comparedconcentration of 2Cr13 steel's inhibition in 1M hydrochloride acid 25℃and in the H2S/CO2-saturated medium, the corrosion rate of 2Cr13 steel was lower in 1M hydrochloride acid 25℃thanin the H2S/CO2-saturated medium.