Synthesis of a green smart nano-carrier encapsulating Allium jesdianum extract for superior corrosion protection in saline environment using natural polymers

This study aims to develop a hybrid corrosion inhibitive system based on employing soy protein isolate/chitosan (SPI/CS) complex nanoparticle as a novel and green smart carrier for active protection of mild steel in 3.5 wt% NaCl solution. For this purpose, the SPI/CS nanocarrier was synthesized and impregnated with aqueous extract of Allium jesdianum (AEAJ) as a green corrosion inhibitor to obtain SPI/CS@AEAJ. The prepared SPI/CS@AEAJ nanoparticles were characterized by various analytical methods, such as FT-IR and SEM. Active corrosion inhibition of the designed system was explored by electrochemical techniques. Results demonstrated the successful loading of AEAJ compounds in the polymeric matrix and the pH-dependent behavior of inhibitor molecules released from SPI/CS@AEAJ. The outcomes of electrochemical impedance spectroscopy (EIS) and polarization measurements manifested significant inhibition performance of about 93.57 % for the hybrid system. Accordingly, the total corrosion resistance increased from 1172 Ω.cm² for the Blank sample to 18255 Ω.cm² for the sample containing a mixture of SPI/CS/AEAJ and zinc cations after 24 h immersion of steel panels, indicating excellent and long-term corrosion protection of the system. The surface characterization methods proved the deposition of surficial inhibitive film on the steel samples arising from chelate formation between organic inhibitors and Zn²⁺ ions.