Surface protection of X80 steel using Epimedium extract and its iodide-modified composites in simulated acid wash solution: A greener approach towards corrosion inhibition

The pure extract of Epimedium (EPM) was investigated as an alternative anticorrosion additive for acid wash and descaling solution simulated using 5% HCl. Static weight loss tests at 30-60 °C and electrochemical measurements were used to determine the corrosion rate. The surface characteristics and functional group analyses were also observed using SEM, AFM, EDS and FTIR techniques. The results show that EPM efficiently inhibits acid corrosion, especially as temperature increases. A small concentration (1.0 g L^-1) of EPM was 96.7% efficient at 60 °C, acting via a simultaneous physical and chemical adsorption mechanism best described by the Langmuir model. The addition of iodide ions was found to favor the synergistic improvement of efficiency at lower concentrations of EPM than at higher concentrations. Acting as a mixed-type inhibitor with predominance for the anodic reaction, EPM adsorption was facilitated mainly by O and N sites decreasing double layer capacitance and increasing charge transfer resistance. Surface morphological profiles and root mean square height parameters indicate that the adsorption of EPM reduces the peaks and pits as well as the surface roughness due to acid attack. EPM could act as an eco-friendly and sustainable alternative corrosion inhibitor for oilfield acid operations.