The corrosion inhibition power of an eco-friendly green inhibitor Ixora coccinea extract (ICE) for mild steel in 1 M HCl and 0.5 M H2SO₄ was analysed using physicochemical and electrochemical techniques. 1–5 v/v% ICE was prepared and added into the corrosive acidic media for different analyses. Weight loss measurements conducted for a period of 24hrs for mild steel immersion revealed 89.38% and 77.96% inhibition capacity of ICE in 1 M HCl and 0.5 M H2SO₄ medium respectively. Electrochemical impedance parameters show that as concentration is increased, efficiency increases and double layer capacitance decreases. Potentiodynamic polarization techniques are also in good agreement with impedance studies and exhibit the mixed type inhibition character of ICE. Electrochemical noise spectrum also strongly supports the anti-corrosive property of ICE and the magnitude of noise signal decreases concerning the increase in ICE concentration. Ixorene, which is one of the major constituents of Ixora coccinea leaves was also studied for its corrosion inhibition nature by quantum mechanical calculations and was found to match with all other results. Adsorption studies of ICE are in accordance with Langmuir isotherm. Surface morphological studies confirm the formation of a protective barrier on mild steel surface in both media, i.e., 1 M HCl and 0.5 M H2SO₄.

The corrosion inhibition efficiency of the Schiff base N,N’-(5,5-dimethylcyclohexane-1,3-diylidene)dianiline (DmChDa) on mild steel in 1M HCl and 0.5M H₂SO₄ was evaluated using gravimetric, electrochemical impedance spectroscopy, potentiodynamic polarization and electrochemical noise measurement. Experimental results established that DmChDa possess relatively high corrosion inhibition capacity. Langmuir and El-Awady adsorption isotherms were obeyed by the Schiff base in 1M HCl and 0.5M H₂SO₄ respectively. SEM analysis showed that DmChDa was adsorbed on the steel surface during corrosion inhibition. The variation of metal dissolution with temperature was also examined using gravimetric study.

Two heterocyclic oximes (E)-N-hydroxy-1-(pyridin-2-yl)methanimine (Hp2ylm) and (E)-N-hydroxy-1-(pyridin-3-yl)methanimine (Hp3ylm) were synthesized from pyridine-2-carbaldehyde and pyridine-3-carbaldehyde, respectively. These oximes were characterized by various spectroscopic tools like UV, IR, MASS and NMR. The inhibition capacity of these oximes against copper corrosion in 0.1 M HNO3 was determined by polarization and impedance spectroscopic studies (EIS). At all concentrations, Hp3ylm exhibited higher inhibition efficiency than Hp2ylm. Attempt was made to illustrate the mechanism of corrosion inhibition by these oximes with the help of adsorption isotherm, scanning electron microscopic (SEM) and quantum chemical studies.

The corrosion inhibition efficiencies of two novel Schiff bases, namely (E)-3-[thiophen-2-ylmethyleneamino]benzoic acid (T2YMABA) and (E)-4-(5-[(2-phenylhydrazono) methyl]thiophen-2-yl)benzoic acid (PHMT2YBA) on mild steel (MS) in 1.0M HCl solution has been investigated and compared using electrochemical impedance spectroscopy and potentiodynamic polarization analysis. The Schiff bases exhibited very good corrosion inhibitions on mild steel in 1.0M HCl medium and the inhibition efficiency increased with the increase in concentration of the inhibitor. Polarization studies revealed that T2YMABA acted as a mixed type inhibitor whereas PHMT2YBA molecules acted as anodic inhibitor.