A pH-Controlled Solid Inhibitor Based on PAM Hydrogel for Steel Corrosion Protection in Wide Range pH NaCl Medium

To provide carbon steel a long-term corrosion protection effect in NaCl solutions with different pH values, based on poly-acrylamide ( ) and oleate imidazoline ( ), a solid corrosion inhibitor with the properties of pH-controlled release was synthesized. SEM, FTIR and TGA results indicated that the inhibitors were successfully loaded into hydrogel with a high encapsulation content (39.64 wt.%). The release behavior from the hydrogel structure has two stages, quick release and sustained release. The pH of solutions could affect the initial release kinetics of inhibitors and the diffusion path in the hydrogel structure. Weight loss measurement of L80 steel in different pH solutions with proved the inhibitor responsive release mechanism and anticorrosion performance. The inhibition efficiency of can maintain over 80% after long-term immersion in a harsh corrosive environment (pH 3), which is much higher than the inhibition efficiency of in a moderate corrosive solution.