In-situ biosynthesized plant exudate gums­silver nanocomposites as corrosion inhibitors for mild steel in hydrochloric acid medium.

Natural gums due to availability, multifunctionality, and nontoxicity are multifaceted in application. In corrosion inhibition applications, their performance, in unmodified form is unsatisfactory because of high hydration rate, solubility issues, algal and microbial contamination, as well as thermal instability. This work attempts to enhance the inhibitive performance of Berlinia grandiflora (BEG) and cashew (CEG) exudate gums through various modification approaches. The potential of biogenic BEG and CEG gums-silver (Ag) nanocomposites (NCPs) for corrosion inhibition of mild steel in 1 M HCl is studied. The nanocomposites were characterized using the FTIR, UV-vis, and TEM techniques. The corrosion studies through the gravimetric and electrochemical (PDP, EIS, LPR, and EFM) analyses reveal moderate inhibition performance by the nanocomposites. Furthermore, the PDP results reveal that both inhibitors are mixed-type with maximum corrosion inhibition efficiencies (IEs) of 61.2 % and 54.2 % for BEG-Ag NCP and CEG-Ag NCP, respectively at an optimum concentration of 1.0 %. Modification of these inhibitors with iodide ion (KI) significantly increased the IE values to 90.1 % and 88.5 % for BEG-Ag NCP and CEG-Ag NCP at the same concentration. Surface observation of the uninhibited and inhibited steel samples using SEM/EDAX, 3D Surface profilometer, and AFM affirm that the modified nanocomposites are highly effective.

An appraisal of the utilization of natural gums as corrosion inhibitors: Prospects, challenges, and future perspectives.

Natural gums are macro compounds containing monosaccharide (sugar) units bonded by glycosidic to form long polymeric sugar chains of considerably high molecular weight. Natural gums are multifaceted in applications with the main areas being the food and pharmaceutical industries. The recent research interest in corrosion inhibitors is considering natural gums because of their abundance and ecological compatibility. Hence, this review takes a look at the use of natural gums in pure and modified forms in metals protection. The review establishes that the corrosion-protecting ability of natural gums has a direct connotation with their macromolecular weights, chemical composition, and molecular and electronic structures. Immersion duration and temperature are other factors found to affect the inhibition performance of natural gums considerably. The inhibition of natural gums in pure form is found not to be excellent due to their high hydration rate, algal and microbial contamination, solubility that depends on pH, and thermal instability. Common modification techniques adopted by corrosion inhibitor scientists are copolymerization, mixing with chemicals to induce synergism, crosslinking, and insertion of inorganic nanomaterials into the polymer matrix. Infusion of biosynthesized nanoparticles approach towards enhancing the corrosion inhibition efficiency of natural gums is recommended for future studies because of the unique characteristics of nanoparticles.