The effect of concentration and temperature on the activities of kenikir (cosmos caudatus) leaf extract as iron corrosion inhibitor in electrolyte solution of NaCl

Ethyl acetate extracts from kenikir leaves contain flavanoid, alkaloids and tannins compounds. This compound can be used as a corrosion inhibitor because it contains nitrogen and oxygen atoms with a pair of free electrons so that it allows adsorbed strongly on the surface of the iron and increases the activity of corrosion inhibition. The inhibitory activity was analyzed by wheel test method or measurement of weight loss in NaCl 1 % medium with variations in concentration, temperature and electron microscopy (SEM) analysis. The inhibitory activity of kenikir leaf extract increases with increasing concentration of inhibitor. The optimum inhibition efficiency of was obtained at a concentration of 32 ppm with an inhibition efficiency of 86.84%. An increase in temperature from 25-55 ° C causes decreased inhibitory activity and achieves optimum inhibition efficiency at 25°C. Kenikir leaf extract has adsorption properties that correspond to the Langmuir adsorption isotherm with free energy of ΔGads of -14.98 KJ/mol. The results of the surface analysis by Scanning Electron Microscopy (SEM) showed that the kenikir leaf extract could inhibit corrosion rates with iron surfaces that had fewer pores than without inhibitors.