ALCOHOLIC EXTRACT OF ANDROGRAPHIS PANICULATA AS CORROSION INHIBITOR ON STAINLESS STEEL IN NATURAL SEA WATER ENVIRONMENT

The inhibition efficacy of Andrographis paniculata leaves extract on the corrosion of stainless steel in Natural sea water environment has been studied by mass loss measurements at various time and temperature. The inhibition efficiency is markedly higher in Natural sea water environment with addition of Andrographis paniculata leaves extract compared with those in the inhibitor free solution. The inhibition efficiency increased with increase of inhibitor concentration but decreased with rise in temperature and exposure time. Corrosion inhibition may be due to the spontaneous physical adsorption of the plant constituents on the surface of stainless steel. Experimental data fitted with the Langmuir and Temkin adsorption isotherms. The corrosion product in the presence and absence of alcoholic extract of the inhibitor on stainless steel surface is analysed by UV and IR studies