Microwave-Induced Synthesis of Chitosan Schiff Bases and Their Application as Novel and Green Corrosion Inhibitors: Experimental and Theoretical Approach

Abstract

Environmentally friendly three chitosan Schiff bases (CSBs) were first time synthesized under microwave irradiation by the reaction of chitosan and aldehydes [benzaldehyde (CSB-1), 4-(dimethylamino)benzaldehyde (CSB-2), and 4-hydroxy-3-methoxybenzaldehyde (CSB-3)] and characterized by IR and NMR spectroscopy. The corrosion inhibition performance of the synthesized inhibitors was studied by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The results show that all the Schiff bases (CSBs) act as effective corrosion inhibitors for mild steel in 1 M HCl solution. Among the synthesized Schiff bases, CSB-3 exhibited the maximum inhibition efficiency of 90.65% at a very low concentration of 50 ppm. The EIS results showed that the CSBs inhibit corrosion by the adsorption mechanism. The PDP results show that all the three Schiff bases are mixed-type inhibitors. The formation of inhibitor films on the mild steel surface was supported by scanning electron microscopy/energy dispersive X-ray analysis and Fourier-transform infrared spectroscopy methods. The adsorption of CSBs on the mild steel surface obeys the Langmuir adsorption isotherm. The theoretical studies via density functional theory and molecular dynamics simulation corroborated the experimental results.

Triazole-modified chitosan: a biomacromolecule as a new environmentally benign corrosion inhibitor for carbon steel in a hydrochloric acid solution

“…35,55 The CS-AMT molecules adsorb on the surface of carbon steel and block the sites which are available for corrosive dissolution whereby causing an increment in the R p values which is correlated with corrosion inhibitive performance. The polarization resistance (R p ) can be used to calculate the inhibition efficiency as given below: 7,8 h% ¼…”

“…5,6 One of the most common strategies to counter this problem is the introduction of organic compounds as corrosion inhibitors to the acid solution. 1,7,8 The adsorption of organic inhibitor molecules on the metal surface prevents direct contact between the metal surface and acid solution. However, most of the organic-based corrosion inhibitors are expensive and toxic to human beings and environment.…”

“…For this reason, researchers are currently focusing on the development of cost-effective and "green" corrosion inhibitors with high efficiency. 1,7,8 In this context, the polymeric molecules having a high molecular weight and thus a greater surface coverage have proved to be promising corrosion inhibitors. Accordingly, carboxymethyl cellulose, Tapioca Starch, Gum Arabic and Chitosan have been reported as promising corrosion inhibitors.…”

“…Further, we rstly reported the microwave-assisted synthesis of chitosan Schiff bases and used them as inhibitors against carbon steel corrosion in 1 M HCl. 7 In continuation of our research work on the development of green corrosion inhibitors, [20][21][22][23] we herein report the synthesis and characterization of chitosan functionalized with 4-amino-5-methyl-1,2,4-triazole-3-thiol (AMT). The selection of triazolic compound is based on the fact that the triazoles are well known for their corrosion inhibition behavior.…”

Synthesis, characterization and application of acrylate-based poly ionic liquid for corrosion protection of C1020 steel In hydrochloric acid solution

“…Also, none natural chemicals have been applied as effective inhibitors. For example; Schiff bases [12][13][14], pyrimidine, thiazole, and imidazole [18][19][20][21][22][23][24][25][26]. Most of these compounds contain O, S, and N atoms in their molecular structure.…”