Effect of Flowing Conditions on the Corrosion Inhibition of Carbon Steel by Extract of Buddleia Perfoliata

Buddleia perfoliata leaves extract has been investigated as a carbon steel corrosion inhibitor in 0.5 M sulfuric acid by using polarization curves, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) at different rotation speeds (0, 250, 500, 1000, and 2000 ppm). Results have shown that for uninhibited conditions, the corrosion rate increases as the rotation speed increased up to 500 rpm, and then decreased with a further increase in the rotation speed; for inhibited solution, corrosion rate was lowest under static conditions and it increased with a further increase in the rotation speed. It was found that inhibitor remains on the metal surface for a few hours, but as the rotation speed increased, it was detached from the surface leaving active sites, increasing with this the susceptibilility towards localysed type of corrosion.