Isolation of Chlorophyll a from Kirinyuh Leaves Chromolaena odorata L.) as Corrosion Bioinhibitor in Mild Steel

Abstract

Chlorophyll a (Chla) is a pigment that is naturally occurring in many green plants. Chla has conjugated double bonds and elements of nitrogen (N), Oxygen (O) that can form complex soluble compounds with metal ions capable of inhibiting corrosion in metal. In this research, chla was isolated from kirinyuh leaves (Chromolaena odorata L.). Chla extraction using acetone was selectively precipitated with dioxane and water with an overall yield of 1.43% from dried kinyiruh. The separation of chla was conducted using various chromatographic techniques, such as sucrose column chromatography with petroleum ether: diethyl ether as eluent and gravitational column chromatography with n-hexane: ethyl acetate as eluent. Chla was tested using thin layer chromatography to test the purity of the chla that provides a red stain under UV 365 nm. The identity of chla had been confirmed by UV-Vis at 400-700 nm. The UV-Vis absorption spectrum of chla showed that a maximum Soret band s at 433 nm, while the Q band was at 655 nm. As observed from the functional groups of Chl, -CH2 stretching of aliphatic groups at 2930 cm-1, C=O vibration at 1634 cm-1, C-O vibration at 1257 cm-1, and C-N vibration at 1444 cm-1. Chla was tested as a corrosion inhibitor of mild steel (SAE/AISI Grade 1022) in a 3% brine solution and seawater. The inhibition tests were carried out using the methods of weight loss and microscope to see the surface of mild steel. The result showed that chla decreased corrosion rate by 0.0036 mm/y with an inhibition efficiency of 60% in 3% brine solution and 0.0096 mm/y with an inhibition efficiency of 77.89% in seawater.