Corrosion evaluation of mild steel and the role of organic inhibitors. Experimental and DFT study

DFT and experimental studies on LaxSr1−xMnO3 perovskite materials show that a Mn-terminated surface with Sr-doping displays good performance in NSR technology.

ObjectivesA regioselective approach has been developed for the synthesis of benzopyranophenazine derivatives using In (OTf)3 as a catalyst in one‐pot synthesis. Further, these synthesized compounds were successfully used as organic corrosion inhibitors on mild steel in 1M H2SO4 solution.MethodsThe synthesized organic inhibitors were confirmed using NMR, and HRMS and their regioselectivity was confirmed by DFT studies using the B3LYP/6‐31G (d, p) basis set. Further, the corrosion, and inhibition efficiencies were confirmed by various methods such as weight loss technique, electrochemical impedance spectroscopy, and potentiodynamic polarization studies.ResultsThe two synthesized compounds MBPPand BBPP show excellent corrosion inhibition properties than the previously reported organic inhibitors, especially, the electron‐donating nature of methoxy‐substituted phenazine derivatives show superior corrosion inhibition properties as 98.96 in 900 ppm than electron withdrawing bromo substituted phenazine derivative in the same concentration which indicates that the electronic structure of the organic inhibitor plays an important role in the corrosion inhibition efficiency of mild steel in an acid medium.ConclusionThe synthesized compound efficiently inhibits the corrosion on the mild steel surface and it forms a barrier on the metal surface. As a result, the phenazine derivatives of both MBPP and BBPP act as very effective corrosion inhibitors and the electron‐donating nature of MBPP shows more inhibition efficiency than BBPP inhibitors.

In a paper of Zhu and co-workers (“Study of the electronic effect and quantitative spectra predictions of o-methoxyanilineterminated monoazonaphthols: a combined experimental and DFT study” by Guoxun Zhu, Yan Lin, Wenxian Zhou, Huacan Song and Zhengquan Li, RSC Advances, 2023, 13, 33736), the authors derived a protocol for the absorption spectra prediction is sulphonated azo naphthols assuming that they exist as single azo tautomers. However, as it is well known before and as shown by the available experimental data and the calculations, performed in this note, the studied dyes exist almost solely in hydrazone tautomeric form, which unavoidably affects the conclusions and linear relations made in the original paper. A detailed benchmarking on the spectra prediction, involving 39 density functionals (33 of them hybrid and 6 – pure) indicates that there is no a functional correctly predicting the absorption spectra of the tautomers in azo naphthols.

Experimental and theoretical studies of methyl 1-(2-chloroacetyl)-4-hydroxy-2,6-diphenyl-1,2,5,6-tetrahydropyridine-3-carboxylate: Insights from synthesis, spectroscopic, crystal structure, Hirshfeld surface, DFT, ELF, RDG, IRI, ADMET and docking studies

Visible absorbing croconium dyes with intramolecular hydrogen bonding: A combined experimental and computational study

DFT calculations were used to investigate the reaction mechanism and guide the optimization of selective O‐alkylation conditions, minimizing side reactions and hazardous waste. The O‐alkylation of 4‐hydroxybenzophenone and 4‐bromophenol was studied to synthesize intermediates for Clomiphene and Tamoxifen. DFT studies revealed that C‐alkylation is thermodynamically controlled, while O‐alkylation is kinetically controlled. Additionally, DFT studies predicted the formation of a mutagenic aziridinium intermediate, a finding that had not been reported previously and was experimentally confirmed. Optimization through response surface methodology achieved over 99% yield and purity, with a scalable process that produced over 100 g of crude product suitable for direct use in drug manufacturing. Analytical techniques, including NMR, mass spectrometry, and HPLC, were employed to characterize the products and identify key impurities. This energy‐ and material‐efficient process is highly suitable for industrial‐scale production.

Anion assisted extraction of U(VI) in alkylammonium ionic liquid: Experimental and DFT studies

Anticancer, antimicrobial, spectral, voltammetric and DFT studies with Cu(II) complexes of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its N(4)- substituted derivatives

New Benzimidazole derivatives as efficient organic inhibitors of mild steel corrosion in hydrochloric acid medium: Electrochemical, SEM/EDX, MC, and DFT studies

Abstract: In order to better understand the mechanism of NOx and N2O precursors (NH3 and HCN) from aspartic acid (Asp) pyrolysis, decomposition reaction networks resulting in the generation of NH3 and HCN were investigated by employing density function theory methods. After several pathways were analyzed in detail, two series of pyrolytic reactions containing three possible pathways were proposed. All the reactants, transition states, intermediates and products were optimized, also the electronic properties on these crucial points were discussed, which shows that Cα acts as the most active site to initiate the pyrolysis reaction, where the direct Cα-Cβ bond breakage, due to the atomic charge population of repulsion, led to one key route for the generation of HCN, and the transfer of Hα from Cα to Cβ resulting in another key route for the generation of HCN, while the transfer of Hα from Cα to N atom of Asp resulting in the key route for the generation of HN3. Further, the kinetic analysis based on speed control method in each key reaction pathway was conducted to further compare the generation of HCN and NH3 under various temperatures. The above results are in accordance with the related experimental results. Keywords: pyrolysis, aspartic acid (Asp), amino acid, DFT DOI: 10.3965/j.ijabe.20160905.2559 Citation: Kang P, Qin W, Fu Z Q, Wang T P, Ju L W, Tan Z F. Generation mechanism of NOx and N2O precursors (NH3 and HCN) from aspartic acid pyrolysis: A DFT study. Int J Agric & Biol Eng, 2016; 9(5): 166－176.

A triazole heterocyclic compound namely 3-(4-ethyl-5-mercapto-1, 2, 4-triazol-3-yl)-1-phenylpropanone (EMTP) was examined for its corrosion protection of mild steel (MS) against 1 M hydrochloric acid medium using gravimetric techniques. EMTP exhibited excellent corrosion protection performance at low and high concentrations towards MS in HCl solution. Comparison of corrosion protection performance of EMTP and its parent triazole and temperature effects of on inhibition efficacy were also studied. EMTP has potential corrosion inhibitor for mild steel in 1.0 M hydrochloric acid solution with the highest protection efficacy of 97% at 303 K. The weight loss findings implied that EMTP protects the metal surface corrosion through the creation of a protective layer at the surface mild steel–corrosive solution interface. The inhibitive efficacy increases with the increase of inhibitor concentration and decreases with increased temperature. The adsorption of EMTP on the surface of MS follows Langmuir’s adsorption isotherm process. DFT method was conducted on EMTP molecule to calculate the quantum chemical parameters and to determine the relationship between the molecular structure of EMTP and protection performance. The molecular parameters, such as energy gap and frontier molecular orbital (highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO)), and the absolute electronegativity (χ) value from inhibitor molecules to unoccupied d-orbital of iron atoms on the mild steel surface were also determined and correlated with protection efficiency. The theoretical findings revealed that the protection performance of EMTP increased with the increase in HOMO energy, and the nitrogen, oxygen and sulfur atoms are most probable positions for bonding through giving electrons to the d-orbital of iron atoms on the mild steel surface.

The partial electron density states (PDOS) have described an obvious charge accumulation between the Al–Mg alloy and the doped atom of Sn through the recognition of the conduction band region. The physicochemical properties of adsorption on the nanosurface are one of the fundamental parameters for determining and choosing the Langmuir adsorption through IR, NMR, UV-VIS, and HOMO/LUMO and charge distribution results. Therefore, in this article, the ONIOM approach has been performed with a three-layered level of the high level of DFT method using EPR-III, 6-31+G (d,p) and LANL2DZ basis sets by the physicochemical software of Gaussian 16 revision C.01, a medium semi-active part that includes important electronic contributions, and a low-level part that has been handled using MM2 force field approaches. Comparing to 〖∆G〗_ads^o amounts approved a good agreement among computed results, as well as the correctness of the selected isotherm for the adsorption process of benzotriazole → Al-Mg-Sn, 2-mercaptobenzothiazole→ Al-Mg-Sn, 8- hydroxyquinoline → Al-Mg-Sn, and 3-amino-1, 2, 4-triazole-5-thiol → Al-Mg-Sn. The infrared spectra for each of these inhibitor-metal alloy surface have been introduced in the frequency range around 500cm-1-4500cm-1 for benzotriazole → Al-Mg-Sn, 2-mercaptobenzothiazole → Al-Mg-Sn, 8- hydroxyquinoline → Al-Mg-Sn and 3-amino-1, 2, 4-triazole-5-thiol → Al-Mg-Sn with the sharpest peak approximately around 1750cm-1 for benzotriazole → Al-Mg-Sn, 2000cm-1 for 2-mercaptobenzothiazole → Al-Mg-Sn, 3000cm-1 for 8- hydroxyquinoline → Al-Mg-Sn and 3900cm-1 for 3-amino-1, 2, 4-triazole-5-thiol → Al-Mg-Sn. Nuclear magnetic resonance has certainly focused on aluminum shielding in the intra-atomic interaction with aluminum, magnesium, and silicon and simultaneously interatomic interaction with other atoms in organic inhibitors through a variety of high, medium, and low layers of ONIOM methods. Al-Sn(14), Al-Sn(19), and Al-Sn(21) in the Al-Mg-Sn alloy surface with the highest fluctuation in the shielding tensors of NMR spectrum generated by intra-atomic interaction direct us to the most influence in the neighbor atoms generated by interatomic reactions of N→Al, O→ Al, S→ Al through the coating and adsorbing process of Langmuir adsorption. Moreover, based on the computed amounts of UV-VIS spectra for benzotriazole, mercaptobenzothiazole, 8-hydroxyquinoline and 3-amino-1, 2, 4-triazole-5-thiol adsorbed on the Al-Mg-Sn alloy surface, there are maximum adsorption bands between 500nm-2000nm wavelengths for these organic heterocyclic inhibitors joint metal alloy which has illustrated a certain peak with approximately 1000nm wavelength.

Cashew nut shell liquid (CNSL) residue as a greener corrosion inhibitor: Experimental and DFT studies of intensifier effect

Probing effect of weak H-bonding on conformational change in ionic liquid: Experimental and DFT studies

Plasma-nanomodified gCN: unveiling the material properties and mechanism behind enhanced SMX degradation in wastewater through detailed experimental and DFT study.