Green β-cyclodextrin-based corrosion inhibitors: Recent developments, innovations and future opportunities

A comprehensive review of β-cyclodextrin polymer nanocomposites exploration for heavy metal removal from wastewater

This review focuses on the application of β-cyclodextrin (β-CD) polymer nanocomposites (NCs) in the heavy metals (HMs) removal from contaminated water sources. This manuscript's originality consists of an in-depth analysis of recent advances in using β-cyclodextrin nanocomposites (β-CD-NCs) to remove HMs from wastewater, highlighting literature gaps, innovations, and challenges in this field, suggesting perspectives on existing theories, and outlining implications for future research directions. Combining nanoparticles with the β-CD polymer yields stable, reusable β-CD-NCs that are effective and efficient in HM adsorption. The article reviews the various techniques for synthesizing β-CD-NCs and their structural characterization. It also includes processing and functionalization strategies to optimize binding capacity and selectivity for specific HMs. The paper reviews mechanisms underpinning HM adsorption through complexation, ion exchange, and electrostatic interactions. It also reviews how adsorption efficiency is affected by different environmental conditions, such as variations in pH, temperature, and competing ions. This will enable case studies on the applications of β-CD-NCs, particularly for addressing global water pollution. Finally, the current limitations and future perspectives are considered, focusing on the further research needed to optimize these materials for sustainable and cost-effective HM removal on a large scale.

A fluorescent signal amplification strategy via host-guest recognition for cortisol detection

Psychological stress is a major contributor to individual health disparities. Accurate and quantitative detection of stress markers is crucial preventing mental health related problems. Supramolecular chemistry is widely used in drug delivery, catalysis, sensors and other applications. However, due to the difficulty of host functionalization such as cyclodextrins and solid-state pillar[n], it is still a challenge to directly realize the detection of guests through host-guest recognition behavior. Here, we reported an atom transfer radical polymerization (ATRP) fluorescent biosensor for direct and selective detection of guest molecule stress marker cortisol, translating molecular recognition behavior into quantifiable detection signals. Realizes quantitative chemical detection and builds a portable and affordable sensing platform for quantitative detection of target molecules without complex cross-linking steps. Overcomes the disadvantages of traditional methods that require the use of antibodies or are difficult to functionalize during the host-guest recognition process. This ATRP fluorescent biosensor was fabricated by employing zinc phthalocyanine (ZnPc) as a photocatalyst under 630 nm wavelength radiation, β-CD-Br15 as a macromolecular initiator, and fluorescein O-methacrylate (FMA-O) as a monomer for polymerization. The system provides ultra-high sensitivity for the detection of cortisol (limit of detection 0.47 ng/mL) and specificity for the detection of cortisol in the presence of interfering substances such as progesterone and urea. Selective and real sample experiments confirm the specificity and scalability of this mechanism can also be customized by the rational design of the host-guest complex to quantitatively detect various molecules. This study confirms the feasibility of using a cyclodextrin-centered macromolecular initiator as a capture and label-free fluorescent biosensor for cortisol, a stress biomarker.

Enhancing Permanence of Corrosion Inhibitors Within Acrylic Protective Coatings for Outdoor Bronze Using Green Nanocontainers

Outdoor bronze statues are constantly exposed to weather conditions and reactive compounds in the atmosphere that can interact with their surfaces. To avoid these interactions, a commonly used method is the application of coatings with corrosion inhibitors. However, a significant limitation of these inhibitors is their gradual loss over time. In this study, we aimed to improve the durability of 5-ethyl-1,3,4-thiadiazol-2-amine (AEDTA), the inhibitor chosen to formulate new acrylic coatings for outdoor bronzes. Methyl-β-cyclodextrin (Me-β-CD) was selected to host the inhibitor due to the capability of cyclodextrins to form complexes incorporating small organic molecules. The complexes of Me-β-CD and AEDTA were prepared and the inclusion of AEDTA was proved by Fourier-transform infrared spectroscopy, X-ray diffraction and nuclear magnetic resonance spectroscopy. Then, acrylic coatings were prepared at different concentrations of the Me-β-CD/AEDTA system. They were thermally aged and monitored every 24 h. To evaluate the volatilization of the corrosion inhibitor, solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) and thermal desorption-GC/MS (TD-GC/MS) analyses were performed during the first 72 h. The results were compared to those of pure AEDTA films and Incralac®. The outcomes showed that Me-β-CD/AEDTA complexes are promising candidates for developing coatings with improved stability and longer retention of AEDTA.

Sodium alginate and its modified counterpart as sustainable-based corrosion inhibitors for N80 pipeline carbon steel: Experimental and theoretical approach

Sodium alginate is a highly promising biopolymer for use as an eco-friendly/green corrosion inhibitor (CI), despite its limited solubility. In this study, a green and water-soluble modified sodium alginate (MSA) salt was synthesized and employed as a CI on pipeline N80 carbon steel (N80CS) in artificial sea water (ASW) medium. Various analytical tools related to surface and structure were utilized to describe the properties of the newly synthesized MSA polymer. Along with surface analyses, the corrosion protection characteristics of MSA on N80CS substrates at various concentrations were examined using gravimetric, traditional, and sophisticated electrochemical experimentations. Tafel polarization tests revealed that MSA exhibited mixed-type CI characteristics, with a predominance of anodic inhibition. Inhibition efficiency of MSA raised with increasing concentration, attaining a maximum of 89.85 and 94.90 % at 500 and 750 ppm, respectively. The physiochemical adsorptions of MSA on the N80CS surface were verified through the Langmuir adsorption model isotherm. The corroborated adsorption of MSA on the N80CS surface through the formed inhibitor thin film to prevent metal corrosion was confirmed by the surface characterizations carried out on inhibited surfaces. The experimentally obtained results were confirmed by the theoretical investigations using the molecular dynamics and density functional theoretical aspects.

Modification of chitosan-ethyl formate polymer with zinc oxide nanoparticles and β-CD to minimize the harmful effects of Alternaria early blight on Vicia faba

Derivatives of chitosan-ethyl formate polymers (Chs-EF) show promise as biologically relevant materials. The novelty of this study lies in the innovative use of Chs-EF doped with zinc oxide nanoparticles and beta-cyclodextrin, which significantly enhances the polymers' protective activities against Alternaria early blight disease in Vicia faba by improving both disease resistance and plant health. After doping Chs-EF with zinc oxide nanoparticles (ZnONPs) and inserting it into the beta-cyclodextrin (CD), two products emerged: Chs-EF/ZnONPs and Chs-EF/CD. Using βCD and ZnONPs to modify the Chs-EF polymer improves the optical properties of the generated polymers. Also, the energy gab values of the modified polymers (Chs-EF/ZnONPs and Chs-EF/βCD) were 3.3 and 3.7 eV, respectively, while energy gab value of the Chs-EF polymer was 3.9 eV. In this study, the effects of ZnONPs, chitosan, β-CD, and Chs-EF/ZnONPs on Alternaria solani early blight disease in Vicia faba plants were investigated. The treatments were evaluated based on disease symptoms and a disease index (DI) to assess their ability to protect against Alternaria early blight disease blight. The results show that the modified polymer with ZnONPs and beta-cyclodextrin (β-CD) and the modified polymer with ZnONPs (Chs-EF/ZnO NPs) provided the best protection, with DI values of 25 % and 12.5 %, respectively. Furthermore, it was discovered that the levels of carotenoids, chlorophyll a, and chlorophyll b in the infected plants had dropped by 52.6 %, 69.2 %, and 36.1 %, respectively. Chs-EF/ZnONPs were the most effective treatment, showing significant increases in the contents of chlorophyll a and b in infected plants by 120.8 % and 225.4 %, respectively. The study revealed that Chs-EF/ZnONPs exhibited a 131 % increase in the total phenolic content of plants, peroxidase (POD) activity (110.6 %), and a 347 % increase in polyphenol oxidase (PPO) activity, respectively, compared to healthy plants. Malondialdhyde (MDA) decreased by 50.7 %, 49.7 %, 43.4 %, 36.6 %, 31.7 %, and 7.5 % in response to Chs-EF/ZnONPs, Chs-EF/β-CD, Chs-EF, ZnONPs, Chitosan, and β-CD, respectively. Also, application of Chs-EF/ZnONPs, Chs-EF/β-CD, Chs-EF, ZnONPs, Chitosan, and β-CD reduced the production of H2O2 by 77.5 %, 62.8 %, 62.5 %, 39.6 %, 22 %, and 15.1 %, respectively, compared to infected controls. We recommend considering these substances as promising candidates for agricultural use, as they may effectively serve as control agents against early blight caused by Alternaria solani.

Application of kartogenin for the treatment of cartilage defects: current practice and future directions

Osteoarthritis and sports injuries often lead to cartilage defects. How to promote its repair and rebuild the smooth cartilage surface has been a hot spot of research in recent years. Kartogenin (KGN), a small molecule discovered in recent years, has been shown to promote the proliferation and chondrogenic differentiation of mesenchymal stem cells (MSCs). As more and more studies have been conducted on KGN, its mechanism of action has been gradually revealed. However, KGN is insoluble in water and therefore easily removed by body fluids. In order to address such issues, a number of systems for efficient intra-articular delivery of KGN have been developed. In addition, due to the complex pathology of cartilage repair, KGN is often used in combination with other drugs to target different stages. In addition, with the rapid development of tissue engineering, scholars have combined KGN with various scaffolds by physical or chemical methods. In this paper, we firstly introduce the general properties of KGN followed by a review of the latest advances in the intra-articular delivery modes of KGN. Finally, we discuss the prospects for the application of KGN in cartilage regeneration, which is aimed at providing a new idea and target for the treatment of cartilage defects.

Chemical, electrochemical, and quantum investigation into the use of an organophosphorus derivative to inhibit copper corrosion in acidic environments

In order to protect the copper against corrosion, a novel corrosion inhibitor known as diphenyl ((2-aminoethyl) amino) (4-methoxyphenyl) methyl) phosphonate (DAMP) was developed. Acid solutions of HCl and H2SO4 were the aggressive solutions employed in this study. Analysis using the FT-IR, 1H-NMR, 31P-NMR, 13C-NMR and BET confirmed that the DAMP was successfully synthesized. The anti-corrosion capabilities of DAMP are evaluated using a combination of chemical, electrochemical and quantum studies. The DAMP has been found to be crucial in preventing the corrosion of copper in both HCl and H2SO4 acid. This was obviously implied by the observation that the corrosion rate of copper in acid solutions decreased when DAMP was added. It is significant to note that 180 ppm produced the highest levels of inhibiting efficiency (96.6% for HCl and 95.2% for H2SO4). The tendency of DAMP to adsorb on the surface of copper through its hetero-atoms (O, N, and P) is the main factor for the anti-corrosion capabilities of DAMP. Results from SEM/EDX tests supported this. The actual adsorption takes place via various active centers, physical and chemical mechanisms that are coordinated with the estimated quantum parameters. Additionally, the adsorption of DAMP adheres to the Langmuir isotherm.

Surface adsorption and corrosion resistance performance of modified chitosan: Gravimetric, electrochemical, and computational studies

Two novel chitosan derivatives (water soluble and acid soluble) modified with thiocarbohydrazide were produced by a quick and easy technique using formaldehyde as links. The novel compounds were synthesized and then characterized by thermogravimetric analysis, elemental analysis, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. Their surface morphologies were examined using scanning electron microscopy. These chitosan derivatives could produce pH-dependent gels. The behavior of mild steel in 5 % acetic acid, including both inhibitors at various concentrations, was investigated using gravimetric and electrochemical experiments. According to the early findings, both compounds (TCFACN and TCFWCN) functioned as mixed-type metal corrosion inhibitors. Both inhibitors showed their best corrosion inhibition efficiency at 80 mg L-1. TCFACN and TCFWCN, showed approximately 92 % and 94 % corrosion inhibition, respectively, at an optimal concentration of 80 mg L-1, according to electrochemical analysis. In the corrosion test, the water contact angle of the polished MS sample at 87.90 °C was reduced to 51 °C. The water contact angles for MS inhibited by TCFACN and TCFWCN in the same electrolyte were greater, measuring 78.10 °C and 93.10 °C, respectively. The theoretical results also support the experimental findings.

Electrochemical and DFT Studies of the Pistacia Integerrima Gall Extract: An Eco-friendly Approach towards the Corrosion of Steel in Acidic Medium

A novel application of the Pistacia integerrima gall extract as an environmentally friendly corrosion inhibitor is reported in this study. The major phytochemicals present in the gall extract, namely pistagremic acid, β-sitosterol, pistiphloroglucinyl ether, pistaciaphenyl ester, naringenin, and 5,7-dihydroxy-2-(4-hydroxyphenyl)-2,3-dihydrochromen-4-one, play key roles in its anticorrosive behavior on steel in aggressive media. Several approaches were used to study the corrosion prevention activity of steel in 1 M H2SO4, including weight loss analysis, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and density functional theory (DFT). At 2000 mg L-1, the highest efficiency of 92.19% was observed in 1 M H2SO4. An SEM study was conducted to validate the surface coverage of the metal surface. DFT studies revealed several nucleophilic regions present in the phytochemicals of the inhibitor, which supported the favorable nucleophilicity. Corrosion studies have not been performed on this sample. Phytochemicals make it an effective corrosion inhibitor, and its extraction process utilizes distilled water, making it better than other inhibitors. It has been proven that the obtained values of ΔEInhDFT for pistiphloroglucinyl, pistaciaphenyl ether, and naringenin organic compounds were very low, confirming the high reactivity of these corrosion inhibitors. The order of the values of ΔEInhDFT is as follows: pistaciaphenyl ether > pistiphloroglucinyl ether > naringenin organic compound; this suggests that pistaciaphenyl ether is more reactive than the other compounds. In this study, P. integerrima gall extract emerges as a novel and highly effective corrosion resistance agent in 1 M H2SO4, chosen for its relevance to acid pickling and cleaning processes.

Selective and Accurate Detection of Nitrate in Aquaculture Water with Surface-Enhanced Raman Scattering (SERS) Using Gold Nanoparticles Decorated with β-Cyclodextrins

A surface-enhanced Raman scattering (SERS) method for measuring nitrate nitrogen in aquaculture water was developed using a substrate of β-cyclodextrin-modified gold nanoparticles (SH-β-CD@AuNPs). Addressing the issues of low sensitivity, narrow linear range, and relatively poor selectivity of single metal nanoparticles in the SERS detection of nitrate nitrogen, we combined metal nanoparticles with cyclodextrin supramolecular compounds to prepare a AuNPs substrate enveloped by cyclodextrin, which exhibits ultra-high selectivity and Raman activity. Subsequently, vanadium(III) chloride was used to convert nitrate ions into nitrite ions. The adsorption mechanism between the reaction product benzotriazole (BTAH) of o-phenylenediamine (OPD) and nitrite ions on the SH-β-CD@AuNPs substrate was studied through SERS, achieving the simultaneous detection of nitrate nitrogen and nitrite nitrogen. The experimental results show that BTAH exhibits distinct SERS characteristic peaks at 1168, 1240, 1375, and 1600 cm-1, with the lowest detection limits of 3.33 × 10-2, 5.84 × 10-2, 2.40 × 10-2, and 1.05 × 10-2 μmol/L, respectively, and a linear range of 0.1-30.0 μmol/L. The proposed method provides an effective tool for the selective and accurate online detection of nitrite and nitrate nitrogen in aquaculture water.

Chitosan/tannic acid phenamine networks-hollow mesoporous silica capsules with reversible pH response: Controlled-releasing amino acid derivatives as "green" corrosion inhibitor

A novel amino acid derivative (SM) was synthesized through Schiff base reaction between syringaldehyde (SA) and methionine (MTI), and loaded to obtain a reversible pH-responsive releasing corrosion inhibitor silica capsule (CS/TA@SM@HMSs) with chitosan/tannic acid phenamine networks on the surface. The corrosion inhibition effect of SM and CS/TA@SM@HMSs on Q235 was studied using electrochemical techniques and surface analysis. The results showed the maximum inhibition efficiency of SM reached to 93.2 % at 200ppm by immersing Q235 in 3.5 wt% NaCl solution. The theoretically calculated electron parameter (the energy gap ΔE = 4.492 eV) indicated that SM molecules were more susceptible to electron transfer with iron surfaces therefore allowing better adsorption on carbon steel surfaces to prevent corrosion. Meanwhile, UV-visible measurements showed that the chitosan/tannic acid phenamine network on the capsule surface responded to changes in pH. The reversible pH-responsive corrosion inhibitor capsule can be switched on and off several times to release SM, demonstrating reversible release and efficient corrosion protection. This study proposes a novel class of "green" amino acid derivative corrosion inhibitors, and establishes a controllable, efficient and reversible pH-responsive release system. A new approach is provided to stimulating the release of corrosion inhibitors in response to long-term corrosion protection of metals.

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.

Pickering Emulsion Stabilized by β-Cyclodextrin and Cinnamaldehyde/β-Cyclodextrin Composite

A Pickering emulsion was prepared using β-cyclodextrin (β-CD) and a cinnamaldehyde (CA)/β-CD composite as emulsifiers and corn oil, camellia oil, lard oil, and fish oil as oil phases. It was confirmed that Pickering emulsions prepared with β-CD and CA/β-CD had good storage stability. The rheological experiments showed that all emulsions had G' values higher than G″, thus confirming their gel properties. The results of temperature scanning rheology experiments revealed that the Pickering emulsion prepared with β-CD and CA/β-CD composites had high stability, in the range of 20-65 °C. The chewing properties of Pickering emulsions prepared by β-CD and corn oil, camellia oil, lard, and herring oil were 8.02 ± 0.24 N, 7.94 ± 0.16 N, 36.41 ± 1.25 N, and 5.17 ± 0.13 N, respectively. The chewing properties of Pickering emulsions made with the CA/β-CD composite and corn oil, camellia oil, lard, and herring oil were 2.51 ± 0.05 N, 2.56 ± 0.05 N, 22.67 ± 1.70 N, 3.83 ± 0.29 N, respectively. The texture properties confirmed that the CA/β-CD-composite-stabilized-emulsion had superior palatability. After 28 days at 50 °C, malondialdehyde (MDA) was detected in the emulsion. Compared with the β-CD and CA + β-CD emulsion, the CA/β-CD composite emulsion had the lowest content of MDA (182.23 ± 8.93 nmol/kg). The in vitro digestion results showed that the free fatty acid (FFA) release rates of the CA/β-CD composite emulsion (87.49 ± 3.40%) were higher than those of the β-CD emulsion (74.32 ± 2.11%). This strategy provides ideas for expanding the application range of emulsifier particles and developing food-grade Pickering emulsions with antioxidant capacity.

Dopamine modified natural glucomannan as a highly efficient inhibitor for mild steel: Experimental and theoretical methods

In this work, Glucomannan was modified with dopamine to synthesize a new polysaccharide Schiff base (GAD). After confirmation of GAD by NMR and FT-IR spectroscopic methods, it was introduced as a sustainable corrosion inhibitor with excellent anti-corrosion action for mild steel in 0.5 M hydrochloric acid (HCl) solution. Employing electrochemical test, morphology measurement, and theoretical analysis, the anticorrosion performance of GAD on mild steel in 0.5 M HCl solution is determined. Maximum efficiency of GAD for suppressing the corrosion rate of mild steel at 0.12 g L^-1 reaches 99.0 %. After immersion in HCl solution for 24 h, the results from scanning electron microscopy indicate that GAD is firmly attached to the mild steel surface by making a protective layer. According to the X-ray photoelectron spectroscopy (XPS), FeN bonds existed on the steel surface indicate the presence of chemisorption between GAD and Fe to form stable complexes attracted to the active position on the mild steel. The effects of Schiff base groups on the corrosion inhibition efficiencies were also investigated. Moreover, the inhibition mechanism of GAD was further illustrated by the free Gibbs energy, quantum chemical calculation and molecular dynamics simulation.

Fructus cannabis protein extract powder as a green and high effective corrosion inhibitor for Q235 carbon steel in 1 M HCl solution

The Fructus cannabis protein extract powder (FP), was firstly used as a green and high effective corrosion inhibitor through a simple water-extraction method. The composition and surface property of FP were characterized by FTIR, LC/MS, UV, XPS, water contact angle and AFM force-curve measurements. Results indicate that FP contains multiply functional groups, such as NH, CO, CN, CO, etc. The adsorption of FP on the carbon steel surface makes it higher hydrophobicity and adhesion force. The corrosion inhibition performance of FP was researched by electrochemical impedance, polarization curve and differential capacitance curve. Moreover, the inhibitive stability of FP, and the effects of temperature and chloride ion on its inhibition property were also investigated. The above results indicate that the FP exhibits excellent corrosion inhibition efficiency (~98 %), and possesses certain long-term inhibitive stability with inhibition efficiency higher than 90 % after 240 h immersion in 1 M HCl solution. The high temperature brings about the FP desorption on the carbon steel surface, while high concentration of chloride ion facilitates the FP adsorption. The adsorption mechanism of FP follows the Langmuir isotherm adsorption. This work will provide an insight for protein as a green corrosion inhibitor.