ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Corrosion inhibition behavior and theoretical study on carbon steel in H₂SO₄ by Schizochytrium extract

Qihui Wang, Xing Zhou, Chongkang Zhao, Ruozhou Wang, Yi Sun, Zhitao Yan, and Xueming Li

School of Civil Engineering and Architecture, Chongqing University of Science and Technology, Chongqing, China

E-mail: qihuiwang@cqust.edu.cn

Received: 28 July 2023  Accepted: 2 October 2023

Abstract:

This study utilized Schizochytrium extract (SE) to explore its protective effect on carbon steel in a 0.5 mol/L H₂SO₄ solution. The main functional groups of SE were investigated by Fourier infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The following conclusions were drawn from electrochemical tests: A corrosion inhibition efficiency of 88.7% was achieved when 1000 mg/L SE was added to a 0.5 mol/L H₂SO₄ solution. The corrosion inhibition efficiency of SE increased with the increase in corrosion inhibitor concentration but decreased with the increase in temperature. From the polarization curves, the primary function of SE is to prevent metal dissolution at the anode. The morphology of the corroded steel surface was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques, and a smoother metal surface was observed when SE was added to the H₂SO₄ solution. Parameters such as dipole moments, Mullikan charges, equivalent surfaces (ESP) and binding energies of the four constituent molecules present in SE were calculated using quantum chemical calculations (QC) and molecular dynamics simulations (MS). It was found that the functional groups that play the role of adsorption are mainly carboxyl groups. In addition, Langmuir adsorption isotherms showed that the extracts could adhere to the metal surface and form a long-lasting protective film, thus effectively inhibiting corrosion.

Keywords: H2SO4; FTIR; Corrosion inhibitor; Carbon steel

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-03130-6

Chemical Papers 78 (2) 909–926 (2024)