Cationic surfactant based on alignate as green corrosion inhibitors for the mild steel in 1.0 M HCl

Abstract

Three cationic surfactants based on alginic acid were laboratory prepared. These compounds were evaluated as corrosion inhibitors utilizing three techniques, namely; weight loss, polarization and electrochemical impedance spectroscopy. The corrosive medium was 1.0 M HCl. The corrosion rate of mild steel in 1.0 M HCl at four different temperatures 25, 40, 55 and 70 °C was investigated gravimetrically. The corrosion rate of mild steel was confirmed electrochemically at 25 °C. It was found that the corrosion inhibition efficiency directly proportionally with the hydrophobic chain length of synthesized inhibitors and also with the plethora of concentration. The inhibition efficiency exhibit a positive trend with raising the solution temperatures as indication for chemisorption. The potentiostatic polarization study revealed that the tested green cationic surfactants act as mixed type inhibitors with predominant control of cathodic reaction. The decreasing in the double layer capacitance obtained from electrochemical impedance measurements refer to increasing the thickness of the formed double layer. The apparent activation energy of the inhibited solution was found to be lower than uninhibited solution as an indication for chemical adsorption.