Study on Corrosion Characteristics of Aluminum Alloy Al3102 in Sulfate-reducing Bacteria Environment and Investigating the Use of Azadirachta indica Leaves Extract in its Control

Abstract

An effort to understand the corrosion characteristics of aluminium Al3102 alloy in a neutral medium in the presence of Desulfovibrio desulfuricans was made. The corrosion rate increased up to tenfold in the bacterial medium in comparison to the control (abiotic) medium. Scanning electron microscopy (SEM) studies showed substantial sulfate-reducing bacteria (SRB) adhesion on the alloy surface and pit formation. Supplementation of 1000 ppm Azadirachta indica leaves extract decreased corrosion by 82%. Sulfide analysis, SEM, and X-ray photoelectron spectroscopy (XPS) studies showed a significant effect of neem leaf extract (NLE) on bacterial metabolic activity and confirmed the adsorption of the inhibitor molecules on Al3102 surface. Electrochemical impedance spectroscopy studies showed that the NLE formed a highly resistive external layer which protected the alloy surface from the corrosive effects. The gas chromatography-mass spectroscopy studies (GC-MS) showed appreciable amount of esters, terpenoids, heterocyclic nitrogen, sulfur compounds, and organic bromine compounds in NLE.