Chitosan derivatives as green corrosion inhibitors for P110 steel in a carbon dioxide environment

Hydrogen inhibition of wet AlLi alloy dust collector systems using a composite green biopolymer inhibitor based on chitosan/sodium alginate: Experimental and theoretical studies

Aluminum‑lithium (AlLi) alloy polishing and grinding processes in wet dust collector systems could cause hydrogen fire and explosion. From the fundamental perspective of preventing hydrogen explosions, a safe, nontoxic, and sustainable modified green hydrogen inhibitor based on chitosan (CS) and sodium alginate (SA) was developed in this study and was used as a hydrogen evolution inhibitor for the processing of waste dust from AlLi alloys. The structure and elemental distribution of the synthesized material were characterized through characterization experiments. Hydrogen evolution experiments and a hydrolysis kinetic model were used to explore the inhibitory effect of modified CS/SA on AlLi alloy dust, and the results revealed that the inhibitory concentration of the hydrogen explosion lower limit was 0.40 wt%, with an inhibition efficiency of 91.93 %, indicating an 11.88-61.44 % improvement over that of CS and SA. As the inhibitor concentration increased and the temperature decreased, the hydrogen inhibition effect increased. Characterization experiments and density functional theory showed that CS/SA primarily formed a dense physical protective barrier on the dust surface through chemical adsorption and complexation reactions, interrupting the hydrogen evolution reaction between the metal and water. This study introduces a novel green modified hydrogen inhibitor that fundamentally addresses hydrogen generation and explosion.

The influence of molecular weight on the anticorrosion properties of chitosan coatings

The effort to replace toxic compounds with natural alternatives led to intensive investigations on the use of polysaccharides as coatings for corrosion protection. Biological macromolecules, such as chitosan, demonstrate great potential for the development of sustainable anticorrosion coatings. However, the role played by important properties, such as molecular weight, on the performance of the coatings, remains unclear. In this paper, the influence of molecular weight on the anticorrosion properties of chitosan coatings is investigated using AA2024-T3 aluminum alloy as substrate. Chitosan of three different molecular weights were used for the preparation of coatings and free-standing films, and their properties (morphology, swelling degree, and water contact angle) were evaluated. The corrosion performance of the coated samples was investigated by an atmospheric corrosion essay and by electrochemical impedance spectroscopy, in NaCl 3.5 % solution. The results show that the low-molecular-weight chitosan coatings present the lowest swelling degree (603 %), highest water contact angle (86.4°), lowest porosity, and superior performance in both corrosion tests, reaching impedances close to 105Ωcm2 even after seven days of exposure to corrosive solution.

Exploration of rice husk ash as a green corrosion inhibitor immersed in NH4Cl 7.5 % solution

The study reports the development of a liquid smoke solution of rice husk ash (RHA) as a green corrosion inhibitor in NH4Cl solution in approaching corrosion protection for refinery facilities. The recent utilization of RHA has a partial solution to address the possible chemical to form a filming layer to disconnect bare metal and their environment. This work prepared the RHA solution by condensing the RHA vapor before adding it to various concentrations. The corrosion test of potentiodynamic and electrochemicals intends to discover the inhibitor's corrosion resistance before examining the electronic transition corresponding to the contribution of several functional groups using Ultraviolet Visible (UV-Vis) and Fourier-Transform Infrared Spectroscopy (FTIR). Surface evaluation intends to unveil the nature of the corrosion by utilizing the Scanning Electronic and Atomic Force Microscope. The corrosion test result shows the depression of corrosion rate to 0.120 mmpy with high efficiency beyond 96 % in the addition of 7.5 ppm RHA inhibitor. The greater Nyquist semicircle diameter at high concentrations increases the adsorption of the RHA on the surface of C1018. The electronic transition of n-π* and π -π* shows an extensive contribution of C[bond, double bond]C, C[bond, double bond]O, and -OH based on the UV-Vis and FTIR test. The formation of a complex compound of Fe-(NH4Cl-RHA)n blocks the corrosion active sites to reduce the corrosion. This study paves the way for using RHA as an organic compound under NH4Cl conditions, such as in a refinery process facility.

Integrating experimental and theoretical studies in the development of a novel alginate-based bio-composite for copper anticorrosion in 3.5 % NaCl environments

The development of new coatings based on a biopolymer, epichlorohydrin-modified alginate, and alginate-epichlorohydrin-SrTiO3 nanocomposites incorporating SrTiO3 (STO) nanoparticles in the alginate (Alg) matrix (Alg-Ep-STO), has been addressed in this study. Various characterization techniques were employed to analyze the prepared compounds, including X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), as well as surface analysis methods such as Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Furthermore, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) methods were used to evaluate corrosion inhibition and protection durability. The results demonstrate that the incorporation of STO nanoparticles into the alginate matrix with epichlorohydrin significantly improved the metal's resistance to corrosion. The experimental findings received reinforcement from various computational methods, including density functional theory (DFT), Molecular Dynamics (MD) and Monte Carlo (MC) simulations, which were employed to investigate the interactions between the Alg-Ep-STO nanocomposite and the copper surface. The computational outcomes revealed that the Alg-Ep-STO nanocomposite exhibits robust adhesion to the copper surface, maintaining a flat orientation, with its alignment being notably influenced by the presence of STO nanoparticles.

Study of okra pectin prepared by sweeping frequency ultrasound/freeze-thaw pretreatment on corrosion inhibition of ANSI 304 stainless steel in acidic environment

Green and efficient metal corrosion inhibitors are very essential, and natural okra pectin (OP) can fulfill this need with rational use of resources. OP was prepared by water-alcohol extraction method after freeze-thaw pretreatment (FTP)/sweeping frequency ultrasound pretreatment (SFUP), and used for corrosion inhibition of ANSI 304 stainless steel (304 SS) in 1 M hydrochloric acid (HCl). The molecular weight, hydrodynamic diameter and monosaccharide composition of OP were analyzed to determine the factors on the corrosion inhibition of 304 SS. During SFUP of okra, the time-domain variation of ultrasound field was monitored by piezoelectric film sensor, its frequency-domain variation was monitored by a hydrophone, and analyzed respectively by oscilloscope and spectrum analyzer. Static weight-loss method, electrochemical and microscopic analyses were used to evaluate the corrosion inhibition efficiency of OP at temperatures (25, 30, 40, 50 °C) and concentrations (0, 0.2, 0.5, 1, 2 g·L-1) to optimize corrosion inhibition performance. It was found that OP by FTP and SFUP had higher corrosion inhibition efficiency on metals in acidic environment. According to static weight-loss method, the corrosion inhibition efficiency of OP with concentration of 2 g·L-1 (25 °C) was improved to 90.27 % in the FTP group and 93.53 % in the SFUP group, which 5.14 % and 8.93 % higher than Control (without pretreatment). Meanwhile, the corrosion inhibition efficiency decreased gradually as the temperature increased. OP corrosion inhibition performance fit Langmuir adsorption isothermal model as a mixed adsorption based on physical adsorption. It was a mixed inhibitor to protect 304 SS from corrosion.

Performance Evaluation of New Chalcone Oxime Functionalized Graphene Oxide as a Corrosion Inhibitor for Carbon Steel in a Hydrochloric Acid Solution

This study aims to synthesize new chalcone oxime functionalized graphene oxide (CO-GO) and investigate the enhancement in corrosion protection. The morphology and structure of the synthesized CO-GO have been characterized by elemental analysis: Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). Moreover, the effectiveness of corrosion inhibition was investigated by utilizing electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The results of the above analyses demonstrate that CO-GO has an outstanding corrosion inhibitor performance of up to 94% and acts as a mixed-type inhibitor with a primarily anodic action. The effect of temperature on a carbon steel surface indicates that the tested composites are chemisorbed. A few techniques were able to provide surface characterization such as scanning electron microscopy and ultraviolet (UV)-visible spectroscopy to confirm inhibitor adsorption on the carbon steel surface.

Efficient removal of mefenamic acid and ibuprofen on organo-Vts with a quinoline-containing gemini surfactant: Adsorption studies and model calculations

To pursue the adsorptivity of versatile vermiculite (Na-Vt)-based adsorbent targeted at emerging pharmaceuticals (mefenamic acid and ibuprofen, corresponding to MEA and IBP, respectively), a quinoline-based gemini surfactant (DHQU) with multi-functional groups is applied as modifier on Na-Vt. Enhanced hydrophobicity, enlarged interlayer space and decreased surface area of DHQU-Vt are obtained, whose modifier availability (the mole ratio of modifier intercalated to added) reaches up to 84.18% as characterized by FT-IR, XRD, TG-DTG, EA and BET analysis. Efficient adsorption of MEA/IBP (123.71/240.69 mg/g) is achieved under an extremely low DHQU dosage (0.2 CEC lower than the usual saturated dosage of organo-Vts), with all the processes fitting satisfactorily with pseudo-second order and Freundlich isotherm models accompanied by an exothermic nature. Acid pickling testifies a stable and reliable reusability process of DHQU-Vt even after 3 cycles. Multiple interactions (i.e., partition process, XH-π interaction, π-π interaction, π-π stacking and electrostatic interaction) are revealed and compared from not only characterization results, but also simulation of frontier orbital analysis, the adsorption configuration and bonding analysis: (i) The greater molecular flexibility of the adsorbate, the greater intra particle diffusion effect. (ii) π-π stacking between isolated aromatic rings is stronger than that between parallelly connected aromatic rings. (iii) The strength of multiple active sites provided by quinoline (CH-π, NH-π and π-π interactions) are comparable but weaker than electrostatic interaction/intra particle diffusion.

Conductive Polymer/SiO2 Composite as an Anticorrosive Coating Against Carbon Dioxide Corrosion of Mild Steel. A Simulation Study

In this work corrosion of mild steel affected by carbon dioxide was studied using a simulation model developed by Nordsveen M. and Nesic S. Using this comprehensive model of the uniform corrosion made possible to predict of corrosion rate of steel in the carbonic acid medium and the influence of different conditions on the anticorrosive property of coated electrode has been investigated. 1D model of corrosion process includes Butler-Volmer and Tafel equations and takes into account both the kinetics of anodic dissolution of an iron and electrochemical discharge of carbonic acid, water and hydrogen ions. The model has been created in COMSOL Multiphysics software and further improvement of this model allowed studying the influence of parameters such as solution composition, the partial pressure of CO2, temperature and flow velocity of the solution on the corrosion rate of the steel. The results of numerical simulation demonstrate that the use of conductive polymerpolypyrrole/ SiO2 composite as an anti-corrosive resin coating reduces the corrosion rate of mild steel by 7 times or more, depending on pH, temperature and flow rate. Furthermore, increasing of flow velocity from 0.1 to 10 m/s affects to the removal of corrosion products from the surface of mild steel and as a result corrosion rate raises from 0.3 to 0.45 mm/year at a temperature of 80 °C and pH=4.

Mitochondrial Fusion and Fission in Neuronal Death Induced by Cerebral Ischemia-Reperfusion and Its Clinical Application: A Mini-Review

Mitochondria are highly dynamic organelles which are joined by mitochondrial fusion and divided by mitochondrial fission. The balance of mitochondrial fusion and fission plays a critical role in maintaining the normal function of neurons, of which the processes are both mediated by several proteins activated by external stimulation. Cerebral ischemia-reperfusion (I/R) injury can disrupt the balance of mitochondrial fusion and fission through regulating the expression and post-translation modification of fusion- and fission-related proteins, thereby destroying homeostasis of the intracellular environment and causing neuronal death. Furthermore, human intervention in fusion- and fission-related proteins can influence the function of neurons and change the outcomes of cerebral I/R injury. In recent years, researchers have found that mitochondrial dysfunction was one of the main factors involved in I/R, and mitochondria is an attractive target in I/R neuroprotection. Therefore, mitochondrial-targeted therapy of the nervous system for I/R gradually started from basic study to clinical application. In the present review, we highlight recent progress in mitochondria fusion and fission in neuronal death induced by cerebral I/R to help understanding the regulatory factors and signaling networks of aberrant mitochondrial fusion and fission contributing to neuronal death during I/R, as well as the potential neuroprotective therapeutics targeting mitochondrial dynamics, which may help clinical treatment and development of relevant dugs.

Plant Extracts as Green Corrosion Inhibitors for Different Metal Surfaces and Corrosive Media: A Review

Natural extracts have been widely used to protect metal materials from corrosion. The efficiency of these extracts as corrosion inhibitors is commonly evaluated through electrochemical tests, which include techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurement. The inhibition efficiency of different extract concentrations is a valuable indicator to obtain a clear outlook to choose an extract for a particular purpose. A complementary vision of the effectiveness of green extracts to inhibit the corrosion of metals is obtained by means of surface characterizations; atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy analysis are experimental techniques widely used for this purpose. Moreover, theoretical studies are usually addressed to elucidate the nature of the corrosion inhibitor—metal surface interactions. In addition, calculations have been employed to predict how other organic substances behave on metal surfaces and to provide experimental work with fresh proposals. This work reports a broad overview of the current state of the art research on the study of new extracts as corrosion inhibitors on metal surfaces in corrosive media. Most constituents obtained from plant extracts are adsorbed on the metal, following the Langmuir adsorption model. Electron-rich regions and heteroatoms have been found to be responsible for chemisorption on the metal surface, whereas physisorption is due to the polar regions of the inhibitor molecules. The plant extracts compiled in this work obtained corrosion inhibition efficiencies above 60%, most of them around 80–90%. The effect of concentration, extraction solvent, temperature, and immersion time were studied as well. Additional studies regarding plant extracts as corrosion inhibitors on metals are needed to produce solutions for industrial purposes.