Investigation and evaluation of neem leaves extract as a green inhibitor for corrosion behavior of mild steel: An experimental study

Abstract

It is a well-established fact that corrosion of mild steels occurs in pipelines, storage tanks, oil reservoirs, boilers, and petrochemicals industries. Green inhibitors are economical, non-toxic and eco-friendly, and forming barrier type layer of organic compounds over metallic materials. In this paper, weight loss, electrochemical measurements containing potential measurements, potentiodynamic polarization and impedance spectroscopy were applied to inspect the neem leaves extract inhibition efficiency and corrosion phenomenon under three conditions (X₁, X₂ and X₃) in 1.0 M HCl medium. The characterization technique including scanning electron microscopy coupled with energy dispersive spectroscopy was conducted to scrutinize the elemental analysis, corrosive pitting and morphology of corrosion products of mild steel immersed in 1.0 M HCl medium with and without neem leaves extract concentration. The corrosion inhibition efficiency of neem leaves extract increased with increasing concentration and conditioning time. By increasing the conditioning time from 0.08 h to 72 h, the corrosion inhibition efficiency of neem leaves extract was increased from 75% to 97%. The neem leaves extract corrosion inhibitor works quite effectively only for 24 h, thereafter its efficiency drastically decreases. For 24 h, neem leaves extract prevented 80–90% corrosion attack but when steel immersion time was increased to 48 h and 72 h, its efficiency decreased from 83% to 65% and 52% to 42%, respectively.