Non-Ionic Polymeric as Acid Corrosion Inhibitor Surfactants of Fatty- Polyethylene Glycol-L-Cysteine

Abbas, Mohamed A.; Adawy, Ahmed I.; Ismail, Amr S.; Nassar, Ibrahim M.

doi:10.21608/ejchem.2024.244108.8761

Non-Ionic Polymeric as Acid Corrosion Inhibitor Surfactants of Fatty- Polyethylene Glycol-L-Cysteine

Document Type : Original Article

Authors

¹ Petroleum Applications Department, Egyptian Petroleum Research Institute, 11727 Nasr City, Cairo, Egypt

² Petrochemicals Department, Egyptian Petroleum Research Institute, 11727 Nasr City, Cairo, Egypt

10.21608/ejchem.2024.244108.8761

Abstract

The current research deals with the elaboration of new non-ionic polymeric surfactants of fatty-polyethylene glycol-L-cysteine composites. Two saturated fatty acids, namely capric acid (CA) ‘decanoic acid’ and lauric acid (LA) ‘dodecanoic acid’, were experimentally employed to react with polyethylene glycol 600 (PEG 600) to produce main ester linkages. Otherwise, cysteine ‘proteinogenic amino acid’ was reacted with PEG 600 to produce thiol side chain structure. The obtained non-ionic polymeric surfactants, capriate L-cysteinate polyethylene glycol (Ib) and laurate L-cysteinate polyethylene glycol (IIb), having dual hydrophilic–hydrophobic sites. The characteristics of the prepared non-ionic surfactants were investigated using several spectroscopic techniques. Surface tension and thermodynamic behaviour as a function of concentration of the designed structures were assigned. The structure IIb that include a taller hydrophobic chain expresses extra surface activity especially at 70 °C comparing with structure Ib, it gives critical micelle concentration (CMC) 1.6x10-3 mole/liter and effectiveness 28.1 mN/m while the standard free energies of adsorption and micellization ∆Gºads -62.3 and ∆Gºmic -18.3 KJ/mole. Polarization plots exhibited that both fatty composites were mixed–type corrosion inhibitors. The maximum inhibition efficiency of Ib and IIb was figured out to be 92 and 93 percent at 10 −2 M, respectively It is found that these prepared composites act as significant corrosion inhibitors and their protection actions proceed the order: IIb>Ib, and they mainly consist of the nature of the component. Morphological characteristics of carbon steel surface prior and next to acidic medium attack is screened. High-resolution features of the corrosion output assured the preservation given by fatty based non-polymeric surfactants on the metal surface exposed to acid solution.

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