Characterization and application of almond gum-silver nanocomposite as an environmentally benign corrosion inhibitor for mild steel in 1 M HCl

Abstract

Almond gum (AG)-Silver (Ag) nanocomposite (AG-AgNC) was biosynthesized and evaluated as a novel, inexpensive and green corrosion inhibitor for mild steel (MS) in 1 M HCl. The fusion of silver nanoparticles (AgNPs) in the AG biopolymer was confirmed by characterizing AG-AgNC by FT-IR, UV–Vis, XRD, EDAX, DLS and TEM techniques. Lattice planes FCC shown by XRD and observance of nano-size AgNPs in DLS and TEM along with the appearance of elemental Ag at 3 KeV in EDAX study confirmed the incorporation of AgNPs in the AG matrix. AG-AgNC was evaluated as an efficient corrosion inhibitor (C·I) from the gravimetric, PDP, EIS analysis of MS in 1 M HCl. AG-AgNC exhibited maximum inhibition efficiency (I.E) of 96.5% at 60 °C at 150 ppm which is almost double the I. E offered by the pristine AG. TGA showed increased thermal stability by the infusion of AgNPs in AG. EIS revealed the formation of an inhibitive barrier film at the MS/solution interface. PDP established that AG-AgNC is exhibiting a mixed-type inhibition. FTIR and UV–Vis described the interaction occurring between AG-AgNC and MS. Adsorption of AG-AgNC on MS followed Langmuir isotherm. SEM image defined improved surface morphology of MS due to the formation of a thin AG-AgNC film on MS. Appearance of O and Ag at 3 KeV in EDAX and mapping of inhibited MS further substantiated the formation of a compact film of AG-AgNC on MS.