Adsorption and Quantum Chemical Studies on the Inhibition Potentials of Some Thiosemicarbazides for the Corrosion of Mild Steel in Acidic Medium

Three thiosemicarbazides, namely 2-(2-aminophenyl)-N phenylhydrazinecarbothioamide (AP4PT), N,2-diphenylhydrazinecarbothioamide (D4PT) and 2-(2-hydroxyphenyl)-N-phenyl hydrazinecarbothioamide (HP4PT), were investigated as corrosion inhibitors for mild steel in H2SO4 solution using gravimetric and gasometric methods. The results revealed that they all inhibit corrosion and their % inhibition efficiencies (%IE) follow the order: AP4PT > HP4PT > D4PT. The %IE obtained from the gravimetric and gasometric experiments were in good agreement. The thermodynamic parameters obtained support a physical adsorption mechanism and the adsorption followed the Langmuir adsorption isotherm. Some quantum chemical parameters were calculated using different methods and correlated with the experimental %IE. Quantitative structure activity relationship (QSAR) approach was used on a composite index of some quantum chemical parameters to characterize the inhibition performance of the studied molecules. The results showed that the %IE were closely related to some of the quantum chemical parameters, but with varying degrees. The calculated/theoretical %IE of the molecules were found to be close to their experimental %IE. The local reactivity has been studied through the Fukui and condensed softness indices in order to predict both the reactive centers and to know the possible sites of nucleophilic and electrophilic attacks

Treated Rhizophora mucronata tannin as a corrosion inhibitor in chloride solution

Treated Rhizopora mucronata tannin (RMT) as a corrosion inhibitor for carbon steel and copper in oil and gas facilities was investigated. Corrosion rate of carbon-steel and copper in 3wt% NaCl solution by RMT was studied using chemical (weight loss method) and spectroscopic (FTIR) techniques at various temperatures in the ranges of 26–90C. The weight loss data was compared to the electrochemical by the application of Faraday’s law for the conversion of corrosion rate data from one system to another. The inhibitive efficiency of RMT was compared with commercial inhibitor sodium benzotriazole (BTA-S). The best concentration of RMT was 20% (w/v), increase in concentration of RMT decreased the corrosion rate and increased the inhibitive efficiency. Increase in temperature increased the corrosion rate and decreased the inhibitive efficiency but, the rate of corrosion was mild with RMT. The FTIR result shows the presence of hydroxyl group, aromatic group, esters and the substituted benzene group indicating the purity of the tannin. The trend of RMT was similar to that of BTA-S, but its inhibitive efficiency for carbon-steel was poor (6%) compared to RMT (59%). BTA-S was efficient for copper (76%) compared to RMT (74%) at 40% (w/v) and 20% (w/v) concentration respectively. RMT was efficient even at low concentration therefore, the use of RMT as a cost effective and environmentally friendly corrosion inhibiting agent for carbon steel and copper is herein proposed

Surface Analysis of 4-Methyl-2-Phenylimidazole Corrosion Inhibitor on Brass

This work presents the first corrosion analysis of 4-methyl-2-phenylimidazole (MePhI) corrosion inhibitor for brass immersed in 3 wt.% NaCl solution, wherein MePhI was shown to be highly effective. Moreover, the structure of the surface layer, the formation of an organo-metallic complex, the spatial distribution of MePhI, and the thermal stability of the MePhI surface layer were described in detail using time-of-flight secondary ion mass spectrometry analysis and X-ray photoelectron spectroscopy. Furthermore, a gas cluster ion beam source using different sizes and accelerating energies of the clusters was also employed to slowly sputter the organic surface layer associated with the surface layer analysis. </jats:p

Surface Analysis of 4-Methyl-2-Phenyl-Imidazole on the Cu Surface

Corrosion problems represent a large portion of the total costs in diverse industrial fields for companies every year worldwide. Moreover, appropriate corrosion control can help avoid many potential disasters that can cause serious issues including loss of life, negative social impacts, and water resource and environmental pollution. It is almost impossible to prevent corrosion, however it is possible to control it. Commonly, organic compounds are used as corrosion inhibitors. The studied compound herein, MePhI, is presented for the first time to protect any metallic material against corrosion. This compound effectively protects copper from corrosion in a highly corrosive chloride solution even after 0.5 year of immersion. To study this system X-ray photoelectron spectroscopy was employed. Using the Tougaard method a surface layer thickness of the MePhI was determined to be 0.3-0.5 nm by analyzing the background of the XPS survey spectrum. Moreover, orientation and the manner of bonding of MePhI on the Cu surface is explained especially by examining the XPS-excited Auger Cu L3M4,5M4,5 spectra, which is a “fingerprint”  of a Cu(I)-MePhI connection. Angle-resolved XPS measurements suggest that both the C and N atoms of the MePhI molecule are involved in the inhibitor surface bonding. Finally, it is also suggested that MePhI molecules are lying flat on the surface.</jats:p

Corrosion Analysis of Fuel Cell Metallic Materials at Elevated Temperature

Corrosion of fuel cell metallic materials cannot be prevented, but there are ways to mitigate it. Environment in the fuel cells can be extremely corrosive and materials for fuel cells construction can deteriorate very fast if appropriate design is not employed [1]. In this work, different metallic materials for fuel cell construction will be tested under various conditions. Especially, an autoclave test will be designed to established corrosion monitoring of these materials at high temperature. Moreover, we will construct an autoclave corrosion cell to monitor corrosion electrochemically by various electrochemical techniques. After the corrosion tests a surface analytical techniques will be employed to reveal the composition of the corroded material (if corrosion will occur) by employing atomic force microscopy, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and secondary ion mass spectrometry. [1] Renato A. Antunes, Mara Cristina L. Oliveira, Gerhard Ett, Volkmar Ett, Corrosion of metal bipolar plates for PEM fuel cells: A review, International Journal of Hydrogen Energy, 35 (2010) 3632–3647. [2] Jixin Chen, Jingwei Hu, James R. Waldecker, Comprehensive Model for Carbon Corrosion during Fuel Cell Start-Up, Journal of The Electrochemical Society, 162 (2015) F878-F889. </jats:p

Time-of-flight secondary ion mass spectrometry analysis of chitosan-treated viscose fibres

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was employed to analyse cellulose viscose fibres treated with different chitosan-based solutions. The analysis reports several new features in the TOF-SIMS spectra for systems with various forms of chitosan-treated surfaces. The characteristic positive ion TOF-SIMS signals for chitosan are reported at m/z 147.90, 207.07, and 221.09, and characteristic signals for trimethyl chitosan are present at m/z 58.03 and 102.09. Furthermore, new fragments were suggested to characterise acetylated chitosan molecules. The relative surface concentrations of different species were obtained based on the specific signal ratios (originating from a specific fragment and cellulose). SIMS imaging was then performed in order to investigate the surface distribution of chitosan, trimethyl chitosan, and Na-containing nanoparticles. In order to perform TOF-SIMS imaging, the above-mentioned characteristic signals were employed and m/z 22.99 was used for Na nanoparticles.status: publishe