Synergistic Effect of Benincasa hispida Peel Extract and KI on the Corrosion Inhibition of Mild Steel in HCl

This study employed Benincasa hispida peel as a raw material for the preparation of Benincasa hispida peel extract (BHPE) via hot water extraction and freeze-drying processes. The synergistic effect of BHPE and KI on the corrosion inhibition of mild steel in 1 M HCl was investigated. The compositional analysis shows that BHPE consists mainly of a mixture of sugars, characterized by a high density of hydroxyl groups and unsaturated functional groups, characteristic of highly effective corrosion inhibitors. Electrochemical experiments and surface analysis show that the composite of BHPE and KI can effectively provide protection to mild steel. Moreover, the synergistic coefficient of BHPE and KI under various concentration conditions was greater than 1, and the highest corrosion inhibition efficiency was 94.4%. In addition, the corrosion inhibition mechanism of BHPE was thoroughly investigated using quantum chemistry (QC) and molecular dynamics simulation (MDS).