The Research Of Synergistic Effects Between Surfactant And Active Anion

The mechanism and significance of inhibition were summarized,and the inhibition effect of surfactant Tween-20 and OP-10 with active anion I~- on the corrosion of cold rolled steel in 0.5-6.0mol/L HC1 was studied with the mass loss method, electrochemical method,and so on.The results show that:surfactant Tween-20 acts as a cathodic inhibitor for steel corrosion in hydrochloric acid,the inhibition efficiency increases with increasing concentration and reaches the peak when 3mg/L,but decreases with an increase in experimental temperature;OP-10 acts as a mixed-type inhibitor for steel corrosion in hydrochloric acid,the inhibition efficiency increases with increasing concentration and reaches the peak when 5mg/L,but decreases with an increase in experimental temperature.In 0.5mol/L HCI,the adsorption of Tween-20,OP-10,Tween-20 with I~- and OP-10 with I~- on steel surface all follow the Langmuir adsorption isotherm.With the addition of 0.1mol/L I~- in 0.5mol/L HCl,the inhibition efficiency of Tween-20 and OP-10 increases with an increase in the two inhibitors,the effect of experimental temperature on inhibition efficiency in not obvious,and the efficiency in 0.5-6.0mol/L HCl reach over 95%.The best combinations are 3mg/L Tween-20 with 0.1mol/L I~- and 5mg/L OP-10 with 0.1mol/L I~-.The adsorption of Tween-20 and OP-10 is a spontaneous process,the process is an exothermic process,which is accompanied by a decrease in entropy.The driving force for the adsorption is the decrease in enthalpy rather than the increase in entropy.Both the complex of Tween-20 with I~- and OP-10 with I~- behave as mixed-type inhibitors,both anodic and cathodic reactions are greatly inhibited,the presence of KI can drastically improve the adsorption of Tween-20 and OP-10 to the steel surface,the result indicates that there is a synergistic inhibition for the steel corrosion in hydrochloric acid.The outer layers of the protective film formed by both the complex of Tween-20 with I~- and OP-10 with I~- are more compacted and thicker than the layer formed by single of them.Surfactant Tween-20 with active anion I~- and OP-10 with I~- meet the demand of effective inhibitors,and designing economical and environmental friendly inhibitors has a bright future in this field.