Evaluation of extract of neem tree (Azadirachta indica) as inhibitor of corrosion in saline medium

Abstract

The inhibition efficiency of corrosion of the extract of neem leaves (Azadirachta indica) on carbon steel and aluminum was evaluated in contact with a sodium chloride and sodium sulfate solution, both at 3.5% p/v. Corrosion speed was determined and it was found that the Neem extract, at a lower concentration, reached better efficiencies on carbon steel in sodium chloride with 78% efficiency using 5% of the extract; concerning the aluminum, the efficiency values reached were low. Besides, through the adjustment to the Langmuir’s isotherms, it was possible to determine that the nem extract was adsorbed spontaneously on the surface of carbon steel and allowed to delay the corrosive process when reaching inhibition efficiencies of 90%. Results of this research allow establishing that the neem extract has a high potential as corrosion inhibitor to be applied in the industry as corrosion preventive medium.