ABSTRACT
SAPODILLA LEAVES EXTRACT (Manilkara zapota L.) AS CORROSION
INHIBITOR OF St.37 STEEL IN HYDROCHLORIC ACID MEDIUM
By:
FILDA AISHA (BP : 1010412012)
Prof. Dr. Emriadi, MS dan Yeni Stiadi, MS
Corrosion inhibition of St.37 steel in hydrochloric acid medium by sapodilla
(Manilkara zapota L.) leaves extract was investigated using weight loss
measurement and potentiodynamic polarization. Results show that the inhibition
efficiency increases with increasing concentration of the extract and decreases
with increasing temperature. The inhibition efficiencies which were obtained
using optimum extract concentration were 81,24% by weight loss method and
85,52 % by potentiodynamic polarization method. Potentiodynamic polarization
method showed that sapodilla leaves extract decrease corrosion current and
increase inhibition efficiency. Inhibitive effect was afforded by adsorption of the
extract on steel surface which was found to accord with Langmuir adsorption
isotherm. FTIR and photo optic confirmed the existence of the adsorbed
protective film on the steel surface.
Keywords: corrosion inhibition, Manilkara zapota L., adsorption,
potentiodynamic polarization, Langmuir adsorption isotherm
