Inhibition behavior of Cu-benzoltriazole-calcium alginate gel beads by piercing and solidification

Abstract

Calcium alginate gel beads loaded with benzotriazole (defined as ‘benzotriazole-calcium alginate gel beads’) were successfully prepared by a piercing-solidifying method. Moreover, the insoluble Cu-benzotriazole complexes were introduced on the surface of these gel beads through the interaction between benzotriazole and Cu2+ to obtain Cu-benzoltriazole-calcium alginate gel beads, which act as the barrier to extend benzotriazole release time. The loading amount of benzotriazole in the Cu-benzoltriazole-calcium alginate gel beads was determined by thermo-gravimetric analysis (TGA) and the releasing process of benzotriazole was traced by UV–vis spectrophotometer. The inhibition behavior of Cu-benzoltriazole-calcium alginate gel beads for Q235 steel in 3.5% NaCl solution was investigated by polarization and electrochemical impedance spectrum techniques. The results show that complete release time of benzotriazole from benzoltriazole-calcium alginate gel beads is about 400 min, and further prolonged to dozens of hours by forming a barrier of insoluble Cu-benzotriazole complexes. In addition, Q235 steel in 3.5% NaCl solution+5.0g/L Cu-benzoltriazole-calcium alginate gel beads exhibit the lower corrosion current density and higher inhibition efficiency (87.06% at 24h) than Q235 steel in 3.5% NaCl solution.