Synergistic inhibition of Q235 steel (QCS) corrosion in H₂SO₄ by silkworm sand extract (Sse) and KI

In recent years, plant extracts had emerged as a promising alternative to conventional corrosion inhibitors, gaining significant attention in green chemistry research. However, using plant extracts alone resulted in the lower corrosion suppression efficiency (
ƞ
). In order to improve the
ƞ
of plant extract, the synergistic corrosion suppression behavior and mechanism of silkworm sand extract (Sse) and potassium iodide (KI) on Q235 steel (QCS) were studied for the first time in 0.5 M H
2
SO
4
. Both weightlessness and electrochemical method demonstrated that
ƞ
of QCS was optimal and exceeded 90% at 30°C in a 0.5 M H
2
SO
4
containing 0.9 g/L Sse and 0.06 g/L KI (Sse/KI). When used alone of 0.9 g·L
-1
Sse and 0.06 g·L
-1
KI,
ƞ
was 71.12% and 40.16% respectively. Therefore, the synergetic effect of Sse and KI gave the corrosion inhibitor excellent corrosion suppression properties. In addition, scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle (CA) demonstrated that Sse/KI could significantly decrease QCS corrosion in acidic environments. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) confirmed that Sse/KI were adsorbed onto the QCS to form a protective film, reducing the QCS damage in acidic environments.