The requirement for abiding by strict environmental protection regulations has caused many
researchers during the past decades to go after using green and cheap compounds available
from renewable sources like plant metabolites (bioactive compounds). Improving the
corrosion prevention effect of various plant extracts is of utmost importance in this regard,
for which a novel nanoemulsion-based strategy is proposed in the present paper. The
corrosion inhibitors that participated in this study included Amaranthus, Althermanthea, and
Cionura erecta (L.) Griseb, which was investigated against mild steel in 0.5 mol·L−1 HCl
media. The presented data were obtained via electrochemical techniques (EIS and
polarization)and surface analyses (SEM). The researchers also used Dynamic light scattering
to evaluate the particles’ sizes in nanoemulsion solutions. Nanoemulsions indicated
hydrodynamic diameter below 500 nm, meanwhile having narrow particle size distribution.
Findings presented that 100 mg/L of Amaranthus extract nanoemulsion resulted in an
inhibition efficiency of 91%, denoting that a slight amount of Amaranthus inhibitor extract
could produce greater efficiency. The SEM analysis results were decisive in proving that the absorption of Amaranthus molecules on the surface of metal decreased its dissolution rate
substantially, producing a smooth and clean surface. One primary reason for the effective
adsorption of extracts on metal surfaces via chelation with iron atoms refers to the presence
of an abundant number of electron donor Oxygen- based atoms in the molecules of different
aerial parts of the extracts. Further description for the extract inhibitory mechanism is the
physical adsorption of the section on the surface layer of metal followed by the Langmuir
adsorption isotherm. The nanoemulsion Amaranthus extract in this process absorbs approx. -
24.7 kJ·mol−1 of free energy. the cytotoxicity test through MTT assay on A172 and
SHSY5Y cell lines was used, revealing the therapeutic impact on initiating cytotoxic
response in neural cell lines, and anticancer activity.
