Chitosan, its derivatives and composites with superior potentials for the corrosion protection of steel alloys: A comprehensive review

A review on chitosan and chitosan-based bionanocomposites: Promising biological macromolecules for sustainable corrosion inhibition

Corrosion is a significant issue affecting industrial metal surfaces, resulting in material degradation, economic losses, and safety concerns. This review comprehensively examines chitosan and its nano and bionanocomposite forms as sustainable, eco-friendly corrosion inhibitors, emphasizing key innovations in their development and application. The article highlights chitosan's ability to form protective films, which inhibit corrosion by creating a barrier on metal surfaces. A key advancement explored is the incorporation of chitosan nanoparticles, which significantly improve corrosion resistance due to their enhanced surface area, increased adhesion properties, and improved mechanical strength. Another innovative aspect is the synergistic effect of combining chitosan with other nanoparticles or inhibitors, resulting in superior corrosion protection and enhanced barrier properties. The review also addresses the chemical modifications of chitosan to overcome challenges such as poor solubility, mechanical weakness, and chemical instability in harsh environments. A novel contribution of this article is the focus on scalable, cost-effective production methods for chitosan-based bionanocomposites, facilitating their industrial application. This review provides a comprehensive summary of literature reports, offering valuable insights into the latest research advancements and highlights future prospects for chitosan-based materials as eco-friendly, high-performance corrosion inhibitors in diverse industrial settings.

Effect of Substituents on Chitosan-Derived Sustainable Corrosion Inhibitors: Experimental and Computational Studies of Inhibition and Adsorption Performance

This work involves the synthesis of two chitosan derivatives by reacting chitosan, extracted from shrimp shells in eastern Morocco, with 2-nitrobenzaldehyde via a Schiff base reaction. An amino derivative of chitosan was then produced by reducing the imine group created by sodium borohydride. We investigated the molecular weight (Mw), crystallinity index (CrI), and degree of deacetylation (DDA) of the isolated chitosan, among other characteristic features. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR) were used to characterize the extracted chitosan (CS), 2-nitroben-chitosan Schiff derivative (CS-2NI), and chitosan amino derivative (CS-2NA). In a corrosive medium of 1 M HCl, the three ligands, CS, CS-2NI, and CS-2NA, were used as mild steel corrosion inhibitors. Electrochemical studies were used to analyze the surface shape and assess the inhibitory efficiency. They reveal a significant inhibitory efficiency of 92.31% for the CS-2NI derivative, highlighting the effectiveness of the imine group (═N-) and the nitro group (-NO2) compared to the two amino groups (-NH2 and -NH-) present in the CS-2NA derivative. To support experimental research, a computational study was carried out that combined the simulated annealing technique. The three inhibitors behave as mixed-type corrosion inhibitors. Thermodynamic analyses and adsorption studies revealed that the tested inhibitors create covalent bonds with the steel surface (chemisorption) as well as physical interactions (physisorption), in accordance with the Langmuir model. The identification of the ligands' adsorption sites on the steel surface was made more accessible by computational methods, demonstrating the relationship between the inhibitory properties and the chemical structure of these biodegradable and biocompatible biopolymers.

Enhancing the corrosion resistance of waterborne epoxy coatings with functionalized biochar

This study utilizes discarded tree leaves as a substrate to synthesize biomass porous carbon nanosheets (PCNS) through high-temperature carbonization and pore-forming treatment, followed by functional modification using carboxymethyl chitosan (CMCS) and the corrosion inhibitor 8-hydroxyquinoline (8-HQ). The functionalized PCNS fillers were incorporated into water-based epoxy (WEP) coatings to enhance corrosion resistance. Electrochemical impedance spectroscopy (EIS) testing showed that after 60 days, WEP/PCNS@CMCS@8-HQ exhibited a low-frequency impedance of 1.7 × 109 Ω cm2 at the lowest frequency, with significantly improved salt spray corrosion performance compared to WEP. The study demonstrates that CMCS effectively captures Cl- and acts as a repair agent, working synergistically with the external corrosion inhibitor 8-HQ to improve the dispersion of PCNS within the WEP matrix and enhance corrosion resistance. These findings indicate that green-modified PCNS offers a promising approach to improving the corrosion resistance of coatings.

The Synergistic Effect of Graphene Oxide in Epoxy Resin on Photocured Coating Films with Anticorrosion and Antibacterial Properties

In this work, graphene oxide (GO) and epoxy-functionalized graphene oxide (GOSi) are chosen as additives and incorporated into epoxy resin (EP) for nanocomposite photo-coating films (GO/EP and GOSi/EP series). Compared to GO/EP, the GOSi/EP nanocomposite demonstrates strong binding and excellent dispersibility, highlighting covalent bonding between GOSi and the epoxy coating. Furthermore, GOSi/EP-based films demonstrated superior thermal stability and adhesion performance on galvanized steel plates. The corrosion performance of the coated galvanized steel is investigated using electrochemical impedance spectroscopy (EIS) and polarization curve analysis (Tafel). The effectiveness of corrosion protection is evaluated based on a combination of photoreactivity, crosslinking density, dispersity, and adhesion properties. Out of all the treated films, the film based on 0.1GOSi/EP exhibited the highest percentage of inhibition (98.89%) and demonstrated superior long-term anticorrosion stability. In addition, the 0.1GOSi/EP based formulation showed remarkable antibacterial activity against S. aureus, resulting in a 92% reduction. This work demonstrates the development of a facile, environmentally friendly functionalized graphene oxide/epoxy photocured film with superior dual functionalities in both anticorrosion and antibacterial properties. These advancements hold promising potential for impactful practical applications.

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.

Chitosan-Surfactant Composite Nanocoatings on Glass and Zinc Surfaces Prepared from Aqueous Solutions

Hydrophobic coatings from chitosan-surfactant composites (ca. 400 nm thick by UV-Vis spectroscopy) for possible corrosion protection were developed on glass and zinc substrates. The surfactants (sodium dodecyl sulfate, SDS or sodium dodecylbenzenesulfonate, and SDBS) were added to the chitosan by two methods: mixing the surfactants with the aqueous chitosan solutions before film deposition or impregnating the deposited chitosan films with surfactants from their aqueous solutions. For the mixed coatings, it was found that the lower surface tension of solutions (40-45 mN/m) corresponded to more hydrophobic (80-90°) coatings in every case. The hydrophobicity of the impregnated coatings was especially significant (88° for SDS and 100° for SDBS). Atomic force microscopy studies revealed a slight increase in roughness (max 1.005) for the most hydrophobic coatings. The accumulation of surfactants in the layer was only significant (0.8-1.0 sulfur atomic %) in the impregnated samples according to X-ray photoelectron spectroscopy. Polarization and electron impedance spectroscopy tests confirmed better barrier properties for these samples (40-50% pseudo-porosity instead of 94%). The degree of swelling in a water vapor atmosphere was significantly lower in the case of the impregnated coatings (ca. 25%) than that of the native ones (ca. 75%), measured by spectroscopic ellipsometry. Accordingly, good barrier layer properties require advantageous bulk properties in addition to surface hydrophobicity.

Research progress on chitosan and its derivatives in the fields of corrosion inhibition and antimicrobial activity

Chitosan stands out as the only known polysaccharide of its kind, second only to cellulose. As the second-largest biopolymer globally, chitosan and its derivatives are extensively used in diverse areas such as metal anti-corrosion prevention, food production, and medical fields. Its benefits include environmental friendliness, non-toxicity, cost-effectiveness, and biodegradability. Notably, the use of chitosan and its derivatives has gained substantial attention and has been extensively researched in the fields of metal anti-corrosion prevention and antibacterial applications. By means of chemical modification or synergistic action, the inherent limitations of chitosan can be substantially improved, thereby enhancing its biological and physicochemical properties to meet a wider range of applications and more demanding application requirements. This article offers a comprehensive review of chitosan and its modified composite materials, focusing on the enhancement of their anticorrosion and antibacterial properties, as well as the mechanisms by which they serve as anticorrosion and antibacterial agents. Additionally, it summarizes the synthesis routes of various modification methods of chitosan and their applications in different fields, aiming to contribute to the interdisciplinary development and potential applications of chitosan in various areas.

Water-soluble chitosan salt as ecofriendly corrosion inhibitor for N80 pipeline steel in artificial sea water: Experimental and theoretical approach

Chitosan, as a proficient biopolymer, has enormous potential as an ecofriendly corrosion inhibitor (CI), but their limited solubility restricts practical applications. Herein, an eco-friendly and water-soluble chitosan salt (CS) was utilized as a green CI on N80 pipeline steel in artificial sea water. Several structural and surface analytical tools were engaged in describing the characteristics of novel CS polymer. The corrosion inhibition efficiencies of CS on steel at different concentrations were investigated through gravimetric, conventional and advanced electrochemical techniques along with the surface analyses. Tafel polarization tests specified that CS performed as mixed-type CI with prevalent anodic inhibition characteristics. At a concentration of 1000 ppm, CS provided an inhibition efficiency (IE) of 96.68 %, following physiochemical adsorptions of CS on N80 surface validated by fitting Langmuir adsorption isotherm. However, the reductions in the values of IE at high temperature specified that the CS is the temperature dependent CIs. Scanning electrochemical microscopic evaluation confirmed the formation of thin CS inhibitors films with high electrochemical stability on N80 steel in saline. The performed surface characterizations on inhibited surfaces validated the adsorption of CS on the N80 surface by forming thin inhibitor film to obstruct metal corrosion. The theoretical simulation studies using molecular dynamics and density functional theory corroborated the experimentally obtained results.

Exploring the Effectiveness of Natural Food Flavors in Protecting Carbon Steel against CO2-Induced Corrosion

Two food flavors, furfuryl mercaptan (2-FFT) and difurfuryl disulfide (DFDS), were investigated as green corrosion inhibitors for the N80 steel in a CO2-saturated solution containing 3.5% NaCl. Experimental methods, quantum chemical calculations, and molecular dynamics simulation were employed to evaluate the effectiveness of 2-FFT and DFDS. The results of the study indicate that both 2-FFT and DFDS act as mixed corrosion inhibitors, with a dominant inhibition effect on the cathodic reaction. 2-FFT is physiochemically adsorbed on the steel surface in a tiled form through the furan ring and the - SH groups as adsorption sites. On the other hand, DFDS is chemisorbed on the steel surface through the - S-S- groups in a parallel manner. DFDS exhibits a higher tendency for electron transfer and stronger adsorption to steel compared to 2-FFT. Overall, this study highlights the potential of natural food flavors as effective and environmentally friendly corrosion inhibitors for carbon steel in CO2-saturated environments. The findings of this research can contribute to the development of sustainable and nontoxic corrosion inhibitors for the oil and gas industry.

Polymeric surfactants as ideal substitutes for sustainable corrosion protection: A perspective on colloidal and interface properties

Surfactants are well known for their colloidal and corrosion inhibition potential (CIP) due to their strong propensity to interact with metallic surfaces. However, because of their small molecular size and the fact that they are only effective at relatively high concentrations, their application in aqueous phase corrosion inhibition is often restricted. Polymeric surfactants, a unique class of corrosion inhibitors, hold the potential to eradicate the challenges associated with using surfactants in corrosion inhibition. They strongly bond with the metallic surface and offer superior CIP because of their macromolecular polymeric structure and abundance of polar functional groups. In contrast to conventional polymeric corrosion inhibitors, the inclusion of polar functional groups also aids in their solubilization in the majority of popular industry-based electrolytes. Some of the major functional groups present in polymeric surfactants used in corrosion mitigation include O (ether), glycidyl (cyclic ether), -CONH2 (amide), -COOR (ester), -SO3H (sulfonic acid), -COOH (carboxyl), -NH2 (amino), - + NR3/- + NHR2/- + NH2R/- + NH3 (quaternary ammonium), -OH (hydroxyl), -CH2OH (hydroxymethyl), etc. The current viewpoint offers state-of-the-art information on polymer surfactants as newly developing ideal alternatives for conventional corrosion inhibitors. The industrial scale-up, colloidal, coordination, adsorption properties, and structural requirements of polymer surfactants have also been established based on the knowledge obtained from the literature. Finally, the challenges, drawbacks, and potential benefits of using polymer surfactants have also been discussed.

Modification of conducting arylidene copolymers by formation of inclusion complexes: synthesis, characterization, and applications as highly corrosion inhibitors for mild steel

Modifying the metal surface is one solution to the industry's growing corrosion problem. Thus, via threading approach and insertion of copolymers (CoP5-7) containing polyarylidenes through the internal cavity beta-cyclodextrin β-CD, novel pseudopolyrotaxanes copolymers (PC5-7) are developed, resulting in mild steel corrosion inhibition. Inhibitors of corrosion based on β-CD molecules adsorb strongly to metal surfaces because of their many polar groups, adsorption centers, many linkages of side chains, and benzene rings. The corrosion inhibition efficiencies IE % statistics have been revised via the Tafel polarization method and Spectroscopy based on the electrochemical impedance (EIS), with PC7 achieving the highest 99.93% in 1.0 M H₂SO₄; they are mixed-type inhibitors. The chemical composition of the resulting PCs is determined with Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) is utilized to examine the morphological structure of the produced polymers, and X-ray diffraction is employed to identify crystallinity. Encapsulating CoP5-7 with β-CD changes the morphological structures and increases the generated PCs' crystallinity. The thermal stability of PCs is studied, indicating the presence of these CoPs within the β-CD cavities enhances their thermal stability. This research will be a stepping stone for developing high-efficiency anti-corrosion coatings and various industrial applications.

Control and prevention of microbially influenced corrosion using cephalopod chitosan and its derivatives: A review

Microbially influenced corrosion (MIC) of metals is an important industrial problem, causing 300-500 billion dollars of economic loss worldwide each year. It is very challenging to prevent or control the MIC in the marine environment. Eco-friendly coatings embedded with corrosion inhibitors developed from natural products may be a successful approach for MIC prevention or control. As a natural renewable resource, cephalopod chitosan has a number of unique biological properties, such as antibacterial, antifungal and non-toxicity effects, which attract scientific and industrial interests for potential applications. Chitosan is a positively charged molecule, and the negatively charged bacterial cell wall is the target of its antimicrobial action. Chitosan binds to the bacterial cell wall and disrupts the normal functions of the membrane by, for example, facilitating the leakage of intracellular components and impeding the transport of nutrients into the cells. Interestingly, chitosan is an excellent film-forming polymer. Chitosan may be applied as an antimicrobial coating substance for the prevention or control of MIC. Furthermore, the antimicrobial chitosan coating can serve as a basal matrix, in which other antimicrobial or anticorrosive substances like chitosan nanoparticles, chitosan silver nanoparticles, quorum sensing inhibitors (QSI) or the combination of these compounds, can be embedded to achieve synergistic anticorrosive effects. A combination of field and laboratory experiments will be conducted to test this hypothesis for preventing or controlling MIC in the marine environment. Thus, the proposed review will identify new eco-friendly MIC inhibitors and will assay their potential in future applications in the anti-corrosion industry.

Chitosan derivatives as promising green corrosion inhibitors for carbon steel in acidic environment: Inhibition performance and interfacial adsorption mechanism

Among the biodegradable polysaccharide, chitosan is widely present in the cell membranes of bacteria and algae and in the cell walls of higher plants. As a promising biopolymer, chitosan has great potential as eco-friendly corrosion inhibitor. Herein, two synthetic chitosan derivatives (N-phenylthiourea chitosan (CS-PT), N-phenyl-O-benzylthiourea chitosan (CS-PT-Bn)) were investigated as high-efficient acidic corrosion inhibitors to deal with the corrosion issue of carbon steel. The anti-corrosion property of the chitosan derivatives was explored by electrochemical tests, surface characterization and theoretical calculations. The experimental results indicate that both CS-PT and CS-PT-Bn present high-efficient inhibition performance with the inhibition efficiency of 98.4% and 98.5% at the concentration of 100 mg/L, respectively. Their adsorption mechanism at steel/solution interface is revealed by quantum chemical calculations, molecular dynamics (MD) and GFN-xTB calculations. It is found that CS-PT and CS-PT-Bn adsorb at the steel/solution interface by forming Fe-N and Fe-S bonds. Compared to CS-PT molecule, the introduction of benzyl group endows CS-PT-Bn molecule with stronger electrostatic effect and hydrophobicity, which favors the interfacial adsorption of CS-PT-Bn molecule on carbon steel surface.

Chitosan modified with bio-extract as an antibacterial coating with UV filtering feature

Benzophenone-3 grafted chitosan (CS-BP-3) was successfully synthesized and applied as an antibacterial coating for the first time. The grafting mechanism is based on the reaction between ketone and primary amine to form imine derivatives and the chemical structure of grafted chitosan was studied by Fourier transform infrared (FT-IR) spectroscopy. Water solubility of BP-3 is enhanced after covalently grafted on chitosan and consequently renders the chitosan coating with UV blocking property. Results of thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) further confirmed the thermal stability of BP-3 modified chitosan is enhanced. The CS-BP-3 coating was applied on a variety of substrates of glass, plastics, wood, and metal. The surface features of the coatings such as morphology, water contact angle (WCA), and surface roughness were investigated. The optical and thermal stabilities of the coatings under UV irradiation were studied for 16 h. Antibacterial activity of CS-BP-3 was evaluated against both Gram-negative and Gram-positive bacteria. And the results of bacterial inhibition by CS-BP-3 coating indicate its potential for future application in food packaging.

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.

Metagenomics diversity analysis of sulfate-reducing bacteria and their impact on biocorrosion and mitigation approach using an organometallic inhibitor

Sulfate-reducing bacteria (SRB) have impacted the biocorrosion process for various industrial sectors, especially in the oil and gas industry. The higher stability over extreme conditions is the key parameter for their survival in such environments. So far, many materials have been tried to minimize or control the growth of SRB. In the present study, an organo-metallic compound of the zinc sorbate (ZS) was successfully synthesized by the simple co-precipitation method and its improved antibacterial activity against SRB. The SRB consortia are enriched from the sub-surface soil sample and identified by 16s rDNA sequencing by targeting the V3-V4 region. The most dominating genera identified with sulfate-reducing capability are Sulfurospirillum (42 %), Shewanella (19 %) Bacteroides (14 %), and Desulfovibrio (8 %). Further biocorrosion experiments are conducted by weight loss methods. Higher corrosion current density (I_corr) and less charge transfer resistance (R_ct) are observed for the SRB consortia. Concurrently, higher R_ct is kept for the inhibitor-included systems. The slowest release of the sorbate into the medium suppressed the growth of the SRB bacterial cells with 86 ± 3 % corrosion inhibition efficiency and prevented further corrosion reactions by forming a protective layer over the surface of the carbon steel API 5LX. The surface analysis strongly confirmed that SRB caused pitting corrosion, which has been suppressed in the inhibitor-included systems.

Green and sustainable chitosan-gum Arabic nanocomposites as efficient anticorrosive coatings for mild steel in saline media

The application of green and sustainable anticorrosive coatings is becoming of upsurge interest for the protection of metallic materials in aggressive environments. Herein, a stable crystalline chitosan/gum Arabic composite (CGAC) nanopowder was successfully synthesized and characterized by various methods. The CGAC nanopowder with different doses (25, 50, 100, and 200 ppm) was used to coat mild steel samples and examined its anticorrosion ability in 3.5 wt.% NaCl solution using gravimetric, electrochemical measurements, and surface characterization techniques. All methods yielded consistent results revealing that nanocomposite coatings can impart good anticorrosive properties to the steel substrate. The obtained protection efficiency was enhanced with increasing CGAC dose in the applied surface layer achieving 96.6% for the 200 ppm-coating. SEM and AFM surface morphologies of uncoated and coated samples after the inundation in the saline solution showed that CGAC coating can block the active corrosive sites on the steel surface, and prevent the aggressive Cl^- ions from attacking the metallic substrate. The water droplet contact angle gave further support as it increased from 50.7° for the pristine uncoated surface to 101.2° for the coated one. The current research demonstrates a promising natural and reliable nanocomposite coating for protecting mild steel structures in the marine environment.

Chemically enhanced primary treatment of dairy wastewater using chitosan obtained from shrimp wastes: optimization using a Doehlert matrix design

Dairy operations generate large volumes of polluted wastewater that require treatment prior to discharge. Chemically enhanced primary treatment (CEPT) is a widely utilized wastewater treatment strategy; but it requires the use of non-biodegradable coagulants that can lead to toxic-byproducts. In this study, chitin from shrimp shell waste is extracted and converted into chitosan. Chitosan was demonstrated to be a natural, low-cost alternative coagulant compatible with the CEPT. Following treatment, dissolved air flotation allowed for the removal of turbidity, COD, and UV₂₅₄ from the synthetic dairy effluent (SDE). Doehlert matrix was used to optimize the chitosan dosage and pH of the CEPT; as well as to model the process. The mechanisms behind the coagulation-flocculation were revealed using zeta potential analysis. FTIR spectroscopy was utilized to confirm the functional groups present on the chitosan. Chitosan with a degree of deacetylation equal to 81% was obtained. A chitosan dose of 73.34 mg/L at pH 5.00 was found to be optimal for the removal of pollutants. Removals of COD, turbidity and UV₂₅₄ were 77.5%, 97.6%, and 88.8%, respectively. The amount of dry sludge generated to treat 1 m³ of SDE was 0.041 kg. Coagulation-flocculation mechanisms involved in chitosan-mediated treatment of SDE involve the neutralization of electrostatic charges carried on the amine groups present in cationic chitosan at pH 5.00. Doehlert matrix proved to be a useful tool in optimizing parameters throughout the coagulation-flocculation process. Chitosan from shrimp waste is a low-cost, eco-friendly coagulant alternative for the removal pollutants from dairy effluent using the CEPT.

Novel Cellulose Derivatives Containing Metal (Cu, Fe, Ni) Oxide Nanoparticles as Eco-Friendly Corrosion Inhibitors for C-Steel in Acidic Chloride Solutions

Novel environmentally-friendly corrosion inhibitors based on primary aminated modified cellulose (PAC) containing nano-oxide of some metals (MONPs), for instance iron oxide nanoparticles (Fe₃O₄NPs), copper oxide nanoparticles (CuONPs), and nickel oxide nanoparticles (NiONPs), were successfully synthesized. The as-prepared PAC/MONPs nanocomposites were categorized using Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and selected area diffraction pattern (SAED) techniques. The data from spectroscopy indicated that successful formation of PAC/MONPs nanocomposites, as well as the TEM images, declared the synthesized PAC/Fe₃O₄NPs, PAC/CuONPs, and PAC/NiONPs with regular distribution with particle size diameters of 10, 23 and 43 nm, respectively. The protection performance of the as-prepared PAC and PAC/MONPs nanocomposites on the corrosion of C-steel in molar HCl was studied by the electrochemical and weight-loss approaches. The outcomes confirmed that the protection power increased with a rise in the [inhibitor]. The protection efficiency reached 88.1, 93.2, 96.1 and 98.6% with 250 ppm of PAC/CuONP, PAC/Fe₃O₄NPs, and PAC/NiONPs, respectively. PAC and all PAC/MONPs nanocomposites worked as mixed-kind inhibitors and their adsorption on the C-steel interface followed the isotherm Langmuir model. The findings were reinforced by FT-IR, FE-SEM and EDX analyses.

Chitosan as a matrix of nanocomposites: A review on nanostructures, processes, properties, and applications

Chitosan is a biopolymer that is natural, biodegradable, and relatively low price. Chitosan has been attracting interest as a matrix of nanocomposites due to new properties for various applications. This study presents a comprehensive overview of common and recent advances using chitosan as a nanocomposite matrix. The focus is to present alternative processes to produce embedded or coated nanoparticles, and the shaping techniques that have been employed (3D printing, electrospinning), as well as the nanocomposites emerging applications in medicine, tissue engineering, wastewater treatment, corrosion inhibition, among others. There are several reviews about single chitosan material and derivatives for diverse applications. However, there is not a study that focuses on chitosan as a nanocomposite matrix, explaining the possibility of nanomaterial additions, the interaction of the attached species, and the applications possibility following the techniques to combine chitosan with nanostructures. Finally, future directions are presented for expanding the applications of chitosan nanocomposites.

Electrophoretically Deposited Chitosan/Eudragit E 100/AgNPs Composite Coatings on Titanium Substrate as a Silver Release System

Due to the possibility of bacterial infections occurring around peri-implant tissues, it is necessary to provide implant coatings that release antibacterial substances. The scientific goal of this paper was to produce by electrophoretic deposition (EPD) a smart, chitosan/Eudragit E 100/silver nanoparticles (chit/EE100/AgNPs) composite coating on the surface of titanium grade 2 using different deposition parameters, such as the content of AgNPs, applied voltage, and time of deposition. The morphology, surface roughness, thickness, chemical and phase composition, wettability, mechanical properties, electrochemical properties, and silver release rate at different pH were investigated. Using lower values of deposition parameters, coatings with more homogeneous morphology were obtained. The prepared coatings were sensitive to the reduced pH environment.

Chitosan derivative corrosion inhibitor for aluminum alloy in sodium chloride solution: A green organic/inorganic hybrid

A novel and eco-friendly chitosan derivative was synthesized as green corrosion inhibitors on C3003 aluminum alloy in 3.5 wt.% NaCl solution. In this paper, CP was prepared by Schiff Base reaction with chitosan and 4-pyridinecarboxaldehyde. Then, TiO₂ was dispersed in CP to prepare CPT nanocomposite. The corrosion inhibition effect of CPT on C3003 aluminum alloy at different concentrations were studied with electrochemical techniques and surface analysis. The results showed that the maximum inhibition efficiency of CPT nanocomposite reaches to 94.5 % at 200 ppm after the immersed in 3.5 wt.% NaCl solution for 72 h. Meanwhile, the contact angle increases to 120° due to the formation of hydrophobic substances. The strategy of organic/inorganic hybrid can provide the inspiration for the development of chitosan corrosion inhibitor with low concentration and high efficiency.

Gum Arabic as an environmentally sustainable polymeric anticorrosive material: Recent progresses and future opportunities

Gum Arabic (GA) is a plant exudate, consisting of glycoproteins (proteins with carbohydrate co-factor or prosthetic group) and polysaccharides mainly consisting of galactose and arabinose. Because of its polymeric nature and tendency to dissolve in water, GA is widely used as anticorrosive materials, especially in the aqueous electrolytes. GA contains various electron rich polar sites through which they easily get adsorbed on metallic surface and behaves as effective anticorrosive materials. Because of its natural and biological origin, GA is regarded as one of the environmental sustainable and edible alternatives to traditional toxic corrosion inhibitors. Present review piece of writing aims to illustrate the assortment of literatures on gum Arabic as a corrosion inhibitor. Limitation of traditional organic corrosion inhibitors and advantages of using GA as an environmental sustainable alternative have also been described along with the mechanism of corrosion inhibition.

Modified Epoxy with Chitosan Triazine Dihydrazide Derivatives for Mechanical and Corrosion Protection of Steel

Modification of the curing exothermic reaction of epoxy resin with polyamine (PA) hardeners by new chemically bonded fillers to improve the mechanical properties and anticorrosion performances of the epoxy coatings is the main goal for wide applications of epoxy coatings. In this work, the chemical structure of chitosan was modified with triazine hydrazide moiety that contains primary, secondary, and tertiary amine groups to act as activator and dangling chain linkers during the curing of epoxy/PA system. Different molecular masses of chitosan were modified with triazine dihydrazide moiety (Ch-TH2), and their chemical structures and surface morphologies were identified. Their thermal stabilities were investigated, and the grafting percentages with triazine hydrazide were determined from thermal analysis. Different weight percentages of Ch-TH2 ranged from 1 to 10 Wt. % were added to the epoxy/PA system, and their curing characteristics, such as heat enthalpy and glass transition temperature, were determined from non-isothermal dynamic scanning calorimetric thermograms. The effects of molecular masses, triazine dihydrazide %, and Ch-TH2 Wt. % on the mechanical, adhesion and anticorrosive properties of the cured epoxy/PA coatings for steel were investigated. The optimum Ch-TH2 Wt. % was selected from 3 to 6 Wt. % to improve the mechanical, adhesion, and anticorrosive properties of the cured epoxy/PA coatings.

Experimental and theoretical investigations of benzoic acid derivatives as corrosion inhibitors for AISI 316 stainless steel in hydrochloric acid medium: DFT and Monte Carlo simulations on the Fe (110) surface

The inhibition efficiency of benzoic acid (C1), para-hydroxybenzoic acid (C2), and 3,4-dihydroxybenzoic acid (C3) towards enhancing the corrosion resistance of austenitic AISI 316 stainless steel (SS) has been evaluated in 0.5 M HCl using weight loss (WL), open circuit potential (OCP), potentiodynamic polarization method, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) analysis. The results obtained from the different experimental techniques were consistent and showed that the inhibition efficiency of these inhibitors increased with the increase in concentration in this order C3 > C2 > C1. In addition, the results of the weight loss measurements showed that these inhibitors followed the Villamil isotherm. Quantum chemical calculations and Monte Carlo simulations have also been used for further insight into the adsorption mechanism of the inhibitor molecules on Fe (110). The quantum chemical parameters have been calculated by density functional theory (DFT) at the B3LYP level of theory with 6-31G+(2d,p) and 6-31G++(2d,p) basis sets in gas and aqueous phase. Parameters such as the lowest unoccupied (E LUMO) and highest occupied (E HOMO) molecular orbital energies, energy gap (ΔE), chemical hardness (η), softness (σ), electronegativity (χ), electrophilicity (ω), and nucleophilicity (ε) were calculated and showed the anti-corrosive properties of C1, C2 and C3. Moreover, theoretical vibrational spectra were calculated to exhibit the functional hydroxyl groups (OH) in the studied compounds. In agreement with the experimental data, the theoretical results showed that the order of inhibition efficiency was C3 > C2 > C1.

Electrophoretic deposition and characterization of chitosan-molybdenum composite coatings

In this paper, the effect of the electric field on the properties of a new chitosan-molybdenum (Chit-Mo) composite coating obtained by electrophoretic deposition (EPD) was investigated. The composite coatings obtained showed different morphologies depending on the conditions used during the deposition process. Chemical composition results and microstructure analysis showed homogeneous distribution of molybdenum in a chitosan matrix. Corrosion test results showed that the Chit-Mo composite coatings can increase corrosion resistance of 1020 steel in NaCl medium (3.5 %). The coatings obtained at 5 V, pH 5.5, and using a low concentration of reagents (suspension 1: chitosan 0.5 g/L and 1 mM sodium molybdate) reached an inhibition efficiency of up to 76.7 %. Therefore, the results obtained in this work prove the achievement of a new class of chitosan-based composite materials with potential application in the protection of metal structures against corrosion.

Synthesis of carboxymethyl chitosan-functionalized graphene nanomaterial for anticorrosive reinforcement of waterborne epoxy coating

In this study, a carboxymethyl chitosan functionalized graphene (CMCS-rGO) nanomaterial was successfully synthesized in aqueous solution by non-covalent functionalization method. Fourier transform infrared, Raman, ultraviolet visible spectroscopy and thermogravimetric analysis confirmed that carboxymethyl chitosan had been successfully anchored on the surface of graphene. In addition, the CMCS-rGO was used as an anticorrosive nanofiller to be added to waterborne epoxy (EP) coatings to protect steel substrates. The corrosion protection behavior of all coatings was tested by electrochemical workstation, and the results proved that the incorporation of well-dispersed CMCS-rGO nanomaterials could significantly improve the anti-corrosion performance of waterborne epoxy coatings. Furthermore, even after 180 days of immersion, the impedance modulus value of the 0.2 % CMCS-rGO/EP at |Z|_f =0.01 Hz was still approximately 2 orders of magnitude higher than that of the EP.