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Title:	Date palm seed extract as green corrosion inhibitor of carbon steel in 0.5 m HCL for oil and gas applications
Authors:	Mohammed Nabaa Jasim (P94279)
Supervisor:	Norinsan Kamil Othman, Assoc. Prof. Ts. Dr.
Keywords:	Carbon steel Corrosion and anti-corrosives Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	22-May-2022
Description:	Extracts from plants have great potential as alternatives to replace inorganic corrosion inhibitors that are generally harmful to the environment and human health. However, some inhibitors are synthetic which is a toxic risk to the environment and human health. Using experimental methods to examine the relation between a corrosion inhibitor and inhibition efficiency is not enough. It is more economical and faster to use computational techniques such as density functional theory (DFT) as predictive tools. Therefore, the purpose of this study was to use the wasted date palm seed extract (DPSE) as a green corrosion inhibitor and investigated its ability to protect carbon steel in hydrochloric acid (HCl) medium. Additionally, provides a fundamental understanding of aromatic adsorption on iron (Fe) surfaces. Prior to the corrosion test, DPSE was obtained by using a solvent extraction method, the extract was dried to produce a dark brown powder. The characteristics of the extract were studied using Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS). To determine the inhibition efficiency (IE%) and corrosion rate (Cr) of corrosion inhibitor, weight loss test (WT) for different immersion times from 72 to 168 hrs at different temperatures from 25 to 65oC and electrochemical methods such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests were carried out. Surface chemical and morphological analyses were performed using Scanning Electron Microscopy (SEM) and X-ray diffraction analysis (XRD). Adsorption isotherm equations were used to evaluate the inhibition mechanism and types of adsorption. Density Functional Theory (DFT) calculations were used to provide fundamental insights into the action mode of DPSE inhibitor as well as to substantiate the experimental results and to provide more detailed information of the mode of donor-acceptor interactions between carbon steel and inhibitor molecule. The FTIR showed that the extract contained hydroxyl (-OH) and methoxyl (-OCH3) functional groups. The GC-MS of the DPSE showed more than 86% fatty acids, which were mainly Oleic, myristic, and caprylic acids. The percentage of IE% increased with the increase in the DPSE concentrations up to 1400 parts per million (ppm), while a concentration of 2000 ppm decreased the IE % and increased Cr values. The weight loss test for different immersion times indicated that the IE% decreased from 94% to 90% when the immersion time was increased from 72 to 168 hrs. In the temperature test, the IE% were 97, 96.3, and 72.7% at temperatures 25, 35, 45, 5,5 and 65℃, respectively. The PDP and EIS showed that the maximum IE% were 92% and 94%, respectively, and the optimum IE% was achieved at 1400 ppm. The presence of a protective layer was confirmed by the SEM, meanwhile, the corrosion products are found to be absent in XRD results. Thermodynamic and kinetic studies followed the Langmuir isotherm and the change of Gibbs (ΔGadso) values were in the range of −33.45 to −38.41 kJ mol−1. The results showed that the DPSE could protect the carbon steel from corrosion through mixture adsorption (physisorption and chemisorption). The DFT depicted the adsorption sites were at the oxygen (O), and carbon (C) atoms as deduced from the Fukui functions, Mulliken atomic charge, and the highest occupied molecular orbital-lowest occupied molecular orbital (HOMO-LUMO) analysis. The DPSE preferred to form chemical bonds by donating electrons to the Fe surface, and the coordinate bonds between the O and C atoms and the metal surface resulted in the high inhibition efficiency value. Additionally, a good correlation between the experimental data and theoretical calculations was obtained.,Ph.D
Pages:	135
Call Number:	TA479.C37M634 2022 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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