Chitosan based titanium and iron oxide hybrid bio-polymeric nanocomposites as potential corrosion inhibitor for mild steel in acidic medium

Biopolymer chitosan (CS), chitosan grafted acrylamide based titanium dioxide (CS-g-PAM/TiO₂) and magnetite (CS-g-PAM/Fe₃O₄) hybrid nanocomposites have been synthesized through free radical graft co-polymerization and successfully validated as corrosion inhibitors for mild steel in 15 % HCl solution. The synthesized compounds have been characterized through FTIR, APC, XRD and TEM. The thermal stability of the nanocomposites was established by TGA. The anticorrosive performance was determined through gravimetric measurements and by electrochemical study. According to EIS technique it was observed that CS-g-PAM/TiO₂ and CS-g-PAM/Fe₃O₄ showed maximum 97.19 % and 95.49 % efficiency respectively. Langmuir adsorption isotherm is obeyed in each case. The activation and adsorption parameters have been determined from isotherm study. FESEM and AFM confirmed better adsorption layer formed by composites over mild steel surface. The elemental composition of the metal samples was proved by the XPS investigation. DFT and ANOVA test further corroborates the experimental results.

Behavior of two classes of organic contaminants in the presence of graphene oxide: Ecotoxicity, physicochemical characterization and theoretical calculations

Graphene oxide (GO) production has increased considerably and therefore its presence in the environment is inevitable. When in aquatic environment GO can interact with co-existing compounds, modifying their toxicities for several organisms. However, the toxic effects of co-exposure of GO and organic compounds are rarely reported in the literature. Herein, we studied the behavior of four organic aquatic contaminants found in surface water such as 2-phenylbenzotriazoles (non-Cl PBTA-9 and PBTA-9) and phenoxyphenyl pesticides, pyriproxyfen (PYR) and lambdacyhalothrin (LCT), in the presence of GO. GO reduced 90% and 83% of the toxicity of non-Cl PBTA-9 and PBTA for Daphnia. When PBTAs were adsorbed onto GO surface their interactions caused GO agglomeration (up to 20 mm) and consequent precipitation, making PBTAs less bioavailable. PYR and LCT's toxicities increased up to 83% for PYR and 47% for LCT in the presence of GO, because their adsorption on GO lead to the stabilization of the suspensions (up to 0.5 μm). Those particles were then easily ingested and retained in the digestive tract of the daphnids, triggering the Trojan horse effect. Based on theoretical calculations we observed that PBTA compounds are planar, electron-poorer and more reactive than the studied pesticides, suggesting a better stability of the GO/PBTA complexes. PYR and LCT are nonplanar, electron-richer and less reactive towards GO than PBTAs, forming less stable GO complexes that could facilitate the desorption of pesticides, increasing toxic effects. Our results suggest that the properties of the organic toxicants can influence the stability of graphene oxide suspensions, playing a fundamental role in the modulation of their toxicity. Further research is needed for a deep understanding of the behavior of nanomaterials in the presence of contaminants and their effect in the toxicity of aquatic organisms.

Tetra-substituted phthalocyanines bearing thiazolidine derivatives: synthesis, anticancer activity on different cancer cell lines, and molecular docking studies

In the first step, (4R)-2-(2-hydroxyphenyl)thiazolidine-4-carboxylic acid (c) and 2-(2-(3,4-dicyanophenoxy)phenyl)thiazolidine-4-carboxylic acid (1) were prepared. Then, the peripherally tetra-substituted metallophthalocyanines [ZnPc (2), CuPc (3), and CoPc (4)] were synthesized by using 1. The structures of the obtained compounds were characterized by common spectroscopic methods. Aggregation behaviors of the tetra-substituted metallophthalocyanines (2-4) were investigated by UV-Vis and fluorescence spectroscopy in the presence/absence of soft metal ions. The electronic spectra of the newly synthesized metallophthalocyanines [ZnPc (2), CuPc (3), and CoPc (4)] were analyzed by the Bayliss method. The fluorescence quantum yield of diamagnetic ZnPc (2) was obtained in DMSO at room temperature. Also, the anticancer activity of the newly synthesized metallophthalocyanine derivatives was studied on C6, DU-145, and WI-38 cell lines and investigated using six concentrations (3.125; 6.25; 12.5; 50; 75; 100 μg L-1). The cell cycle and apoptosis analyses of CuPc (3) were performed. In addition, the chemical and biological activities of 2-(2-(3,4-dicyanophenoxy)phenyl)thiazolidine-4-carboxylic acid (1) and its novel type metallophthalocyanines [ZnPc (2), CuPc (3), and CoPc (4)] were compared with many parameters obtained from the Gaussian software and molecular docking methods.

Diaryl Sulfide Derivatives as Potential Iron Corrosion Inhibitors: A Computational Study

The present work aimed to assess six diaryl sulfide derivatives as potential corrosion inhibitors. These derivatives were compared with dapsone (4,4′-diaminodiphenyl sulfone), a common leprosy antibiotic that has been shown to resist the corrosion of mild steel in acidic media with a corrosion efficiency exceeding 90%. Since all the studied compounds possess a common molecular backbone (diphenyl sulfide), dapsone was taken as the reference compound to evaluate the efficiency of the remainder. In this respect, two structural factors were examined, namely, (i) the effect of replacement of the S-atom of diaryl sulfide by SO or SO₂ group, (ii) the effect of the introduction of an electron-withdrawing or an electron-donating group in the aryl moiety. Two computational chemical approaches were used to achieve the objectives: the density functional theory (DFT) and the Monto Carlo (MC) simulation. First, B3LYP/6-311+G(d,p) model chemistry was employed to calculate quantum chemical descriptors of the studied molecules and their geometric and electronic structures. Additionally, the mode of adsorption of the tested molecules was investigated using MC simulation. In general, the adsorption process was favorable for molecules with a lower dipole moment. Based on the adsorption energy results, five diaryl sulfide derivatives are expected to act as better corrosion inhibitors than dapsone.

Recent Advances in Corrosion Science Applicable To Disposal of High-Level Nuclear Waste

High-level radioactive waste is accumulating at temporary storage locations around the world and will eventually be placed in deep geological repositories. The waste forms and containers will be constructed from glass, crystalline ceramic, and metallic materials, which will eventually come into contact with water, considering that the period of performance required to allow sufficient decay of dangerous radionuclides is on the order of 10⁵-10⁶ years. Corrosion of the containers and waste forms in the aqueous repository environment is therefore a concern. This Review describes the recent advances of the field of materials corrosion that are relevant to fundamental materials science issues associated with the long-term performance assessment and the design of materials with improved performance, where performance is defined as resistance to aqueous corrosion. Glass, crystalline ceramics, and metals are discussed separately, and the near-field interactions of these different material classes are also briefly addressed. Finally, recommendations for future directions of study are provided.

Molecular modelling of compounds used for corrosion inhibition studies: a review

Molecular modelling of organic compounds using computational software has emerged as a powerful approach for theoretical determination of the corrosion inhibition potential of organic compounds. Some of the common techniques involved in the theoretical studies of corrosion inhibition potential and mechanisms include density functional theory (DFT), molecular dynamics (MD) and Monte Carlo (MC) simulations, and artificial neural network (ANN) and quantitative structure-activity relationship (QSAR) modeling. Using computational modelling, the chemical reactivity and corrosion inhibition activities of organic compounds can be explained. The modelling can be regarded as a time-saving and eco-friendly approach for screening organic compounds for corrosion inhibition potential before their wet laboratory synthesis would be carried out. Another advantage of computational modelling is that molecular sites responsible for interactions with metallic surfaces (active sites or adsorption sites) and the orientation of organic compounds can be easily predicted. Using different theoretical descriptors/parameters, the inhibition effectiveness and nature of the metal-inhibitor interactions can also be predicted. The present review article is a collection of major advancements in the field of computational modelling for the design and testing of the corrosion inhibition effectiveness of organic corrosion inhibitors.

DFT study of the fouling deposition process in the steam generator by simulating the adsorption of Fe2+ on Fe3O4 (0 0 1)

In order to reveal the fouling problem on the outer surface of the steam generator (SG) tube in the secondary circuit condition of pressurized water reactor (PWR) nuclear power plant, based on the density functional theory (DFT) method, the Cambridge sequential total energy program package (CASTEP) is used to simulate seven kinds of highly symmetric adsorption structure models of termination with tetrahedral Fe (A termination) and termination with octahedral Fe (B termination) on Fe₃O₄ (0 0 1) surface. The adsorption energies and stable adsorption conformations are calculated. The results show that the most stable adsorption structures of the Fe²⁺/Fe₃O₄ (0 0 1) configurations are Fe²⁺ above Fe-O bond of B layer termination (Fe₃O₄(001) A-b). During the adsorption, the Fe-Fe, Fe-O bond length, and Fe-Fe-O bond angle of (0 0 1) surface change, and the atomic positions parallel and perpendicular to (0 0 1) surface change correspondingly. The change happened to the surface layer is the most drastic one. The calculation of charge population, the density of states (DOS), and electron local function of Fe²⁺/Fe₃O₄ (0 0 1) optimal adsorption configuration show that there is electron transfer between Fe²⁺ and Fe₃O₄ (0 0 1), and the adsorption type is chemisorption. Among them, Fe (Fe²⁺)-Fe (Fe₃O₄) forms a metal bond, and Fe (Fe²⁺)-O (Fe₃O₄) forms the ionic bond. The results illustrate the interaction between free Fe²⁺ and Fe₃O₄ is the reason of the nucleation and agglomeration of Fe₃O₄ scale and it provides the foundation for the further research on Fe₃O₄ scale deposition.

Chromeno-carbonitriles as corrosion inhibitors for mild steel in acidic solution: electrochemical, surface and computational studies

Three novel N-hydrospiro-chromeno-carbonitriles namely, 2-amino-7,7-dimethyl-1',3',5-trioxo-1',3',5,6,7,8-hexahydrospiro[chromene-4,2'-indene]-3-carbonitrile (INH-1), 3-amino-7,7-dimethyl-2',5-dioxo-5,6,7,8-tetrahydrospiro[chromene-4,3'-indoline]-2-carbonitrile (INH-2) and 3'-amino-7',7'-dimethyl-2,5'-dioxo-5',6',7',8'-tetrahydro-2H-spiro[acenaphthylene-1,4'-chromene]-2'-carbonitrile (INH-3) were synthesized using the principles of green chemistry and applied as corrosion inhibitors for mild steel in acidic medium using computational simulations and experimental methods. Experimental and computational studies revealed that inhibition effectiveness of the INHs followed the sequence: INH-3 (95.32%) > INH-2 (93.02%) > INH-1 (89.16%). The investigated compounds exhibit mixed-type corrosion inhibition characteristics by blocking the active sites on the surface of mild steel. EIS study revealed that the INHs behave as interface-type corrosion inhibitors. EDX analyses supported the adsorption mechanism of corrosion inhibition. A DFT study carried out for gaseous and aqueous forms of inhibitor molecules indicated that interactions of INHs with the mild steel surface involve charge transfer phenomenon or donor-acceptor interactions. A Monte Carlo (MC) simulation study revealed that only a fractional segment of the molecule lies parallel to the steel surface, since the INH molecules are not completely planar. The results of computational studies and experimental analyses were in good agreement.

Optimizing the composition of LiFSI-based electrolytes by a method combining simplex with normalization

The optimizing method of electrolyte formulation is always vital for the development of high-performance lithium-ion batteries. Traditional optimization methods are mainly aimed at the optimization of the electrolyte composition type, and less attention is paid to the optimization of the composition proportion in a certain electrolyte formulation. In this paper, in order to balance the relationship between aluminum (Al) foil corrosion inhibition and battery electrochemical performance, the electrolyte system LiFSI_0.6–LiBOB_0.4–EC/DEC/EMC (1 : 1 : 1, by volume) was optimized by combining the simplex method, normalization and electrochemical testing. A lithium iron phosphate (LiFePO₄) cathode with the optimized electrolyte of LiFSI_0.53–LiBOB_0.35–EC/DEC/EMC (1.3 : 1.5 : 1.5) delivers a high capacity (143.1 mA h g⁻¹ at 0.5C) and remarkable cycle life (94.9% retention after 100 cycles) at 45 °C. The outstanding performance is attributed to the composition of the cathode electrolyte interphase (CEI) containing the solid and dense LiF, AlF₃, B₂O₃ and Li₂CO₃. This provides a new method and idea for future electrolyte formulation optimization.

The manuscript addresses that the electrolyte system with five components was optimized by combining the simplex method, normalization and electrochemical testing in lithium-ion batteries. The optimized electrolyte is better than commercial electrolyte LiPF₆–EC/DEC.

Evaluation of in vitro inhibitory effects of some natural compounds on tyrosinase activity and molecular docking study: Antimelanogenesis potential

Tyrosinase enzyme is a functional oxidase that is extensively divided in nature. It is the main enzyme in melanin synthesis and is also involved in designating the color of mammalian hair and skin. Additionally, it is accountable for the unfavorable enzymatic browning that happens in plant-derived foods, limiting the shelf-life of new-cut crops with the resultant economic harm. Recently, there has been a remarkable concern to study the inhibitory activity of the tyrosinase enzyme and some inhibitory molecules isolated from natural sources. For tyrosinase enzyme, afzelin, narcissoside, justiciresinol, thalassiolin B, carpachromene, neobavaisoflavone, and kojic acid (as standard) as natural phenols have IC₅₀ values in the range of 2.37-7.90 µM. Theoretical methods, such as gaussian software program and molecular modeling, were used to compare the biological and chemical activity values of molecules. To compare the biochemical and chemical activity values of molecules, chemical activities with quantum chemical parameters, and biological activities against tyrosinase with the ID of 5M8L molecules were investigated.

Corrosion Behavior of Titanium in Simulated Body Solutions with the Addition of Biomolecules

Titanium is one of the most used biomaterials for different applications. The aim of this study is to investigate the influence of adenine, thymine, and l-histidine as important biomolecules in the human body on the corrosion behavior of titanium in simulated body solutions. Open circuit measurements, potentiodynamic measurements, electrochemical impedance spectroscopy measurements, and quantum chemical calculations were employed during the investigation. All electrochemical methods used revealed that the investigated biomolecules provide better corrosion resistance to titanium in artificial body solutions. The increase in corrosion resistance is a result of the formation of a stable protective film on the metal surface. Also, quantum chemical calculations are in compliance with electrochemical test results and indicate that adenine, thymine, and l-histidine may act as corrosion inhibitors in the investigated solutions.

Investi̇gati̇on of pyrazoly derivatives schi̇ff base li̇gands and thei̇r metal complexes used as anti-cancer drug

In this study, six pyrazole derivatives containing hetero atoms have been analyzed using theoretical calculation method. The ligands were tested by HF, B3LYP and M06-2X methods using 3-21G, 6-31G, 6-31G(d, p), and sdd basis sets. The results showed that Ligand 5 has a HOMO value of -7.470 at HF / 6-31g (d.p) level. These ligands were investigated in IR, NMR, and UV-VIS spectrum, then experimental values were compared with IR and NMR spectrum data. The solvents, whose effects were investigated in UV-VIS spectrum, were gas phase (ε = 1), toluene (ε = 2.3741), chloroform (ε = 4.7113), methanol (ε = 32.613), water (ε = 78.3553), and n-methylformamide-mixture (ε = 181.56). Metal complexes of tested ligands were produced with copper, nickel, and zinc. Lastly, the interactions between these six pyrazole derivatives and three proteins, namely 3dju, 2IJN, and 1JNX, were also examined. Biological and anti-cancer properties of six pyrazole derivatives were analyzed by DockingServer. In docking calculations, Estimated Free Energy of Binding value of Ligand 5 was found to be -4.87, -4.82, -1.73 respectively, which indicated the highest biological activity.

Preparation and Application of Modified Imidazole with MPEG (Polyethylene Glycol Monomethyl Ether) as Carbon Steel Inhibitor

The inhibition effect of three inhibitors with different chain lengths of their ether groups on Q235 steel in 0.5 M HCl solution at 318 K was determined by means of weight loss measureme nt, electrochemical methods (Tafel and EIS) and surface analysis (SEM). Moreover, the further study of corrosion inhibition mechanism was also conducted by computational methods (Quantum chemical calculations and Molecular dynamics simulations). Results reveal that the three inhibitors exhibit an excellent inhibition performance for carbon steel, and the corrosion inhibition efficiency of the three inhibitors increases with the increase of the chain length, which favors the formation of a protection film adsorbed on the surface. Analysis of polarization data informs that the adsorption type of three inhibitors basically obeys the Langmuir monolaye r adsorption, which is mainly of chemisorptive nature. Computational methods also tell that the three inhibitors possess a high reactivity and strong interaction with the iron surface, furthermore, the interaction is increased with the increase of the chain length of three inhibitors. The conclusion is in good agreement with the experimental results.

Efficient tribological properties of azomethine-functionalized chitosan as a bio-lubricant additive in paraffin oil: experimental and theoretical analysis

A simple condensation of chitosan (from shrimp shells) and 4-hydroxybenzaldehyde was performed to yield bio-lubricant additive comprised of azomethine functional groups to be used with paraffin lube oil in industries. The synthesized Schiff base derivative of chitosan (SBC) additive was characterized using a CHN analyzer and FT-IR spectroscopy, and the thermal stability was explored using thermogravimetry. The rheological properties of SBC additives in paraffin oil were studied and are discussed herein. The tribological properties of SBC were tested in paraffin as the base oil employing a four-ball tester with different experimental conditions (viz. the concentration of the additive, applied load, speed and time duration), following ASTM D4172A standards. The optimum concentration of the additive in the base oil was found to be 150 ppm, exhibiting minimum coefficient of friction, but with higher concentrations of additive in base oils, the coefficient of friction increased. UV-Vis spectroscopy studies were also performed to confirm the formation of SBC and dispersion stability. The determined tribological parameters, such as the coefficient of friction, mean wear scar diameters and mean wear scar volumes, were found to significantly reduce the coefficient of friction of paraffin oil upon the addition of SBC. The state of steel balls upon exposure to various experimental conditions was analyzed and explained based on outcomes from FESEM, EDX, ferrography and AFM spectroscopy. The insights into interactions of the synthesized SBC with the metal surface were explored using ab initio density functional theory, Fukui indices, molecular dynamics simulation and radial distribution function.

Schiff base derivative of chitosan as biolubricant additive explored in paraffin lube oil.

Optoelectronic parameters of peripherally tetra-substituted copper(ii) phthalocyanines and fabrication of a photoconductive diode for various conditions

In this study, the molecular structure of 4-(4-(trifluoromethoxy)phenoxy)phthalonitrile (1) has been elucidated and its supra-molecular dynamics have been revealed by the analysis of single crystal X-ray diffraction measurements.

Electrochemical and adsorption behaviors of thiadiazole derivatives on the aluminum surface

The electrochemical and adsorption behaviors of BODTA were studied in a 3.0 wt% NaCl solution via different electrochemical methods. Different concentrations of 2,5-bis(octyldithio)-1,3,4-thiadiazole (BODTA) were dissolved in rolling oil, and then aluminum electrodes coated with rolling oil were applied as the working electrode. The morphology and the elements of the electrode surface were studied via SEM, EDS and XPS. Results showed that BODTA had a slight inhibition efficiency of 10.75% when its concentration was 0.1 wt%; however, with the changes in the BODTA concentration from 0.3 wt%, 0.5 wt% to 0.7 wt%, BODTA had an antagonistic effect on the aluminum surface and accelerated the corrosion. The corresponding inhibition efficiencies became negative, which were −21.53%, −30.34%, and −18.82%. The analysis of elements and chemical states on the surface indicated that Al–N and Al–S bonds were formed between aluminum and BODTA. Furthermore, quantum chemical calculations were also performed, which manifested that N and S atoms were the main reactive sites. S atoms on side chains had a stronger reactivity than those in the thiadiazole ring. Finally, the present study was helpful to understand the electrochemical and adsorption behaviors of BODTA on aluminum, and made contributions to the application of BODTA in rolling oil.

Electrochemical and adsorption behaviors of thiadiazole derivatives on the aluminum surface were investigated by an experimental and quantum chemical approach.

Multidimensional insights involving electrochemical andin silicoinvestigation into the corrosion inhibition of newly synthesized pyrazolotriazole derivatives on carbon steel in a HCl solution

Herein, the anti-corrosion of carbon steel in 1 M HCl by two newly synthesized pyrazolotriazole derivatives, namely, 6-methyl-1H-pyrazolo[5,1-c][1,2,4]triazole-7-carbonitrile (CPT) and 1-acetyl-6-methyl-1H-pyrazolo[5,1-c][1,2,4]triazole-7-carbothioamide (MPT), was studied using electrochemical, density functional theory (DFT), and molecular dynamics (MD) simulation techniques. The experimental results showed that the concentrations of inhibitors had a significant influence on their inhibition efficiencies. Potentiodynamic polarization curves indicated that the two pyrazolotriazoles were mixed-type inhibitors. DFT calculations were employed to explore the molecular activity, and MD simulations were performed to obtain the interaction energy between the inhibitor molecules and the iron surface. The findings obtained using the theoretical calculation techniques were consistent with those obtained via experiments.

Anti-corrosion of carbon steel in 1 M HCl by 6-methyl-1H-pyrazolo[5,1-c][1,2,4]triazole-7-carbonitrile and 1-acetyl-6-methyl-1H-pyrazolo[5,1-c][1,2,4]triazole-7-carbothioamide, was studied using electrochemical, DFT and molecular dynamics simulation techniques.

The effect of an N-heterocyclic compound on corrosion inhibition of J55 steel in sweet corrosive medium

The corrosion inhibition behavior of a naphthoxazinone derivative 1-phenyl-1,2-dihydronaphtho[1,2-e][1,3]oxazin-3-one (PNO) on J55 steel in 3.5 wt% NaCl solution saturated with carbon dioxide was evaluated using weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization.