Surface coverage and corrosion inhibition effect of Rosmarinus officinalis and zinc oxide on the electrochemical performance of low carbon steel in dilute acid solutions
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Electrochemical analysis of the corrosion inhibition and surface protection properties of the combined
admixture of Rosmarinus officinalis and zinc oxide on low carbon steel in 1 M HCl and H2SO4 solution
was studied by potentiodynamic polarization, open circuit potential measurement, optical microscopy
and ATR-FTIR spectroscopy. Results obtained confirmed the compound to be more effective in HCl solution,
with optimal inhibition efficiencies of 93.26% in HCl and 87.7% in H2SO4 acid solutions with mixed
type inhibition behavior in both acids. The compound shifts the corrosion potential values of the steel
cathodically in HCl and anodically in H2SO4 signifying specific corrosion inhibition behavior without
applied potential. Identified functional groups of alcohols, phenols, 1�, 2� amines, amides, carbonyls (general),
esters, saturated aliphatic, carboxylic acids, ethers, aliphatic amines, alkenes, aromatics, alkyl
halides and alkynes within the compound completely adsorbed onto the steel forming a protective covering.
Thermodynamic calculations showed physisorption molecular interaction with the steel’s surface
according to Langmuir and Frumkin adsorption isotherms. Optical microscopy images of the inhibited
and uninhibited steels contrast each other with steel specimens from HCl solution showing a better
morphology
Keywords
TJ Mechanical engineering and machinery, TP Chemical technology