Mixed Inhibitor Research Articles

An investigation of modified dialdehyde starch as a highly efficient green corrosion inhibitor for carbon steel in 1 M HCl medium: Synthesis, experimental and theoretical studies

Compared to small organic molecule corrosion inhibitors, polymer corrosion inhibitors offer numerous advantages in terms of adsorption coverage on the metal surface and the presence of multiple active sites for adsorption. A dialdehyde starch Schiff base was synthesized by modification of natural polymer starch and tetraethylene pentaamine, and it was characterized by X-ray diffraction, gel chromatography and thermogravimetry. The corrosion inhibition behaviors of dialdehyde starch Schiff base as an oligomer for low carbon steel in 1 M HCl were investigated. Compared to the common starch derivatives, the dialdehyde starch Schiff base has good water solubility and inhibition performance. The inhibition efficiency can reach 93.2% with 0.16 mM in 1 M HCl solution at 333 K. Double aldehyde starch Schiff base is a mixed corrosion inhibitor that mainly inhibits cathodic reactions. Its adsorption on the surface of carbon steel follows the Langmuir adsorption equation, and the nitrogen -containing groups in the molecules are adsorbed on the surface of the steel through physical and chemical reactions. Quantum chemical calculations confirmed the experimental results.

Ultrasonic-Assisted Decoloration of Polysaccharides from Seedless Chestnut Rose (Rosa sterilis) Fruit: Insight into the Impact of Different Macroporous Resins on Its Structural Characterization and In Vitro Hypoglycemic Activity.

Pigments within polysaccharides pose significant challenges when analyzing their structural characteristics and evaluating their biological activities, making decolorization a crucial step in purifying these biomolecules. In this research, a novel approach using ultrasound-assisted static adsorption with macroporous resins was employed to decolorize polysaccharides extracted from seedless chestnut rose (Rosa sterilis S. D. Shi) fruit (RSP). Among the fourteen tested resins, AB-8, D101, D4020, HPD100, and S8 were identified as the most effective, demonstrating superior decoloration efficiency and polysaccharide recovery. Further examinations of RSPs treated with these five resins revealed distinct effects on their uronic acid levels, monosaccharide makeup, molecular weight, surface structure, and hypoglycemic properties. The RSP treated with HPD100 resin stood out for having the highest uronic acid content, smallest particle size, and lowest molecular weight, leading to the most notable inhibition of α-glucosidase activity through a mixed inhibition model. The application of HPD100 resin in the decolorization process not only potentially preserved the macromolecular structure of RSP but also enhanced its hypoglycemic efficacy. These findings provide a solid theoretical basis for further exploring RSP as a component of functional foods, underscoring the effectiveness of the ultrasound-assisted resin adsorption method in polysaccharide purification.

Experimental Study on the Effect of Mixed Thermodynamic Inhibitors with Different Concentrations on Natural Gas Hydrate Synthesis

Natural gas hydrate (NGH) is a potential future energy resource. More than 90% of NGH resources exist in the pore medium of seafloor sediments. During the development of deep-sea oil and gas fields, wellbore pipelines are often clogged due to the synthesis of gas hydrates, and the addition of thermodynamic inhibitors is a common solution to prevent hydrate synthesis. In this paper, the effects of two single inhibitors, sodium chloride and ethylene glycol, as well as hybrid inhibitors combining these two inhibitors on the synthesis of methane hydrates were investigated using the self-developed one-dimensional gas hydrate exploitation simulation test apparatus. The effects of single and hybrid inhibitors were investigated in terms of the hydrate synthesis volume and gas–water two-phase conversion rate. The results show that the hybrid inhibitor has a better inhibitory effect on hydrate synthesis with the same initial synthesis driving force. When the concentration of inhibitors is low, salt inhibitors can have a better inhibitory effect than alcohol inhibitors. However, in the mixed inhibitor experiment, increasing the proportion of ethylene glycol in the mixed inhibitor can more effectively inhibit the synthesis of hydrates than increasing the proportion of sodium chloride in the mixed inhibitor.

Unveiling the tyrosinase inhibitory potential of phenolics from Centaurium spicatum: Bridging in silico and in vitro perspectives

Phenolics, abundant in plants, constitute a significant portion of phytoconstituents consumed in the human diet. The phytochemical screening of the aerial parts of Centaurium spicatum led to the isolation of five phenolics. The anti-tyrosinase activities of the isolated compounds were assessed through a combination of in vitro experiments and multiple in silico approaches. Docking and molecular dynamics (MD) simulation techniques were utilized to figure out the binding interactions of the isolated phytochemicals with tyrosinase. The findings from molecular docking analysis revealed that the isolated phenolics were able to bind effectively to tyrosinase and potentially inhibit substrate binding, consequently diminishing the catalytic activity of tyrosinase. Among isolated compounds, cichoric acid displayed the lowest binding energy and the highest extent of polar interactions with the target enzyme. Analysis of MD simulation trajectories indicated that equilibrium was reached within 30 ns for all complexes of tyrosinase with the isolated phenolics. Among the five ligands studied, cichoric acid exhibited the lowest interaction energies, rendering its complex with tyrosinase the most stable. Considering these collective findings, cichoric acid emerges as a promising candidate for the design and development of a potential tyrosinase inhibitor. Furthermore, the in vitro anti-tyrosinase activity assay unveiled significant variations among the isolated compounds. Notably, cichoric acid exhibited the most potent inhibitory effect, as evidenced by the lowest IC50 value (7.92 ± 1.32 µg/ml), followed by isorhamnetin and gentiopicrin. In contrast, sinapic acid demonstrated the least inhibitory activity against tyrosinase, with the highest IC50 value. Moreover, cichoric acid exhibited a mixed inhibition mode against the hydrolysis of l-DOPA catalyzed by tyrosinase, with Ki value of 1.64. Remarkably, these experimental findings align well with the outcomes of docking and MD simulations, underscoring the consistency and reliability of our computational predictions with the actual inhibitory potential observed in vitro.

Managing hypertension using brewing bioactive peptides as angiotensin-converting enzyme inhibitors: Impact on vascular tone through ex vivo assays

BackgroundPeptides derived from brewer’s spent grain (BSG) and yeast (BSY) are promising natural substitutes of synthetic drugs to manage hypertension as inhibitors of angiotensin-converting enzyme (ACE). However, their impact on the vascular function, so far, remains to be verified. Accordingly, we aimed to evaluate the effect of brewing peptides on the arterial vasocontractile response to angiotensin (Ang) I (through vascular ACE-inhibition) to estimate their antihypertensive potential. The impact of the oral route (gastrointestinal digestion, intestinal absorption, and liver metabolism) in brewing peptides was also investigated. MethodsIliac arteries from adult spontaneously hypertensive rats were studied with isometric tension recording. After ensuring the function integrity of the arteries, concentration-response curves to addition of Ang I (10−9-10−6 M) were performed after 30 min incubation with MIX (50:50 mixture of BSG:BSY) or BSG (0.86 mg/mL), or captopril (an ACE-inhibitory drug) or Krebs solution. ResultsMIX peptides (without simulated oral administration) enhanced Ang I-induced vasoconstriction, but lacked vascular effects after simulated oral administration. By contrast, BSG peptides (without simulated oral administration) did not exhibit vascular effects, whereas they promoted a marked decrease in vasocontraction evoked by the generated Ang II after simulation of the oral route, implying their capability to inhibit ACE. Additionally, to elucidate this inhibitory mechanism, Michaelis-Menten and Lineweaver-Burk plots indicated a mixed inhibition type. ConclusionWith simulation of the oral route, BSG peptides were able to inhibit vascular ACE with a similar efficacy as the antihypertensive drug captopril, suggesting the potential to mitigate the burden of hypertension.

Green Synthesizing and Corrosion Inhibition Characteristics of Azo Compounds on Carbon Steel under Sweet Conditions: Experimental and Theoretical Approaches.

The deterioration of carbon steel in saline solutions enriched with carbon dioxide represents a significant challenge within the oil and gas industry. So, this study focuses on the design and structural analysis of four azo derivatives: 4-(2-quinolinylazo)-catechol (AZN-1), 4-(4-phenoxyphenylazo)-1-naphthol (AZN-2), 4-(4-pyridylazo)-1-naphthol (AZN-3), and 4-(2-pyridylazo)-1-naphthol (AZN-4), and their first application as effective corrosion inhibitors for carbon steel in a carbon dioxide saturated 3.5% sodium chloride solution. Spectroscopic methods were used to characterize the structural configurations of these compounds. The corrosion protection properties of these compounds on carbon steel in a carbon dioxide saturated 3.5% sodium chloride solution (under sweet conditions) were investigated using Tafel polarization (PDP), electrochemical impedance spectroscopy (EIS), and field emission-scanning electron microscopy (FE-SEM) studies. The results indicate that the inhibition efficiency increases as the concentration of the inhibitors increases. There is a notable agreement between the results obtained from the PDP and EIS measurements, supporting the findings. Moreover, the results displayed that these compounds had significant corrosion protection capabilities at low concentrations, ranging from 91.0 to 98.3% at an additive concentration of 5 × 10-4 M. The PDP profiles showed that these compounds acted as mixed inhibitors, and their adsorption behavior followed the Langmuir isotherm model. Besides, EIS results corroborate the adsorption of AZN compounds through a reduction in double-layer capacitance (Cdl) alongside an augmentation in polarization resistance (Rp) after the addition of AZN compounds into the corrosive solution. Field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the formation of a protective layer on the surface of carbon steel when these inhibitors were applied. In addition, computational calculations and Monte Carlo simulations were performed to support the experimental observations, gain insights into the adsorption properties, and elucidate the corrosion inhibition mechanisms of these compounds.

A new study on the corrosion inhibition mechanism of green walnut husk extract as an agricultural waste for steel protection in HCl solution

In this study, green walnut husk (GWH) extract was explored as a cost-effective (waste-agricultural) and eco-friendly inhibitor to increase the corrosion resistance of carbon steel in a 1 M HCl solution. Electrochemical impedance spectroscopy, weight change, and potentiodynamic polarization (PDP) tests were utilized to examine the electrochemical behavior of steel substrates with and without the inhibitor. Atomic force microscopy (AFM), field emission scanning microscopy, Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were performed to analyze corroded surface structures with and without the inhibitor. This inhibitor was found to be 27–82 % efficient in increasing the corrosion resistance of the steel substrates. When the temperature of the solution was increased from 303 to 323 K, the retardation coefficient decreased due to the physical adsorption of GWH molecules on the surface. The results indicated that GWH acted as a mixed inhibitor, and its adsorption on the surface followed the Langmuir model. AFM measurements showed that the roughness of corroded surfaces decreased by approximately 22 % when the GWH concentration was at its optimum level of 400 ppm. Thermodynamic studies displayed a decrease in the corrosion reaction's activation energy of about 25 %. FTIR and XRD patterns of corroded surfaces represented that hydrated iron chloride was the dominant corrosion product. Furthermore, the results provided insight into the GWH adsorption mechanism.

Origanum Grosii Extracts as Novel Eco-Friendly Corrosion Inhibitors for Mild Steel In HCl Medium.

Two green inhibitors extracted from an endemic species (Origanum grosii (Og)) using two solvents of different polarity (water and ethanol), OgW (aqueous extract) and OgE (ethanolic extract), were used for the anticorrosion of mild steel (M steel) in a 1 M HCl medium. Anticorrosive performance of OgW and OgE was assessed using standard electrochemical techniques, EIS/PDP measurements, weight loss method and SEM/EDX surface analysis. The results show that OgW achieves a maximum inhibition efficiency of 92 % and that the extract in aqueous medium (more polar) is more efficient than the extract in ethanolic medium (less polar). Both extracts act as mixed inhibitors and their corrosion process is predominantly governed by a charge transfer. Concentration and temperature effect was studied and shown that they are two antagonistic parameters for the evolution of inhibitory effectiveness of both OgW and OgE. The adsorption isotherms of the two inhibitors OgE and OgW obey to the Langmuir adsorption model. Moreover, the examination of SEM images and EDX spectra support a deposit of both extracts on the metal surface by an adsorption phenomenon. Besides, theoretical approach of the molecular structures of the major compounds M-OgW and M-OgE and inhibition efficiency was examined via DFT calculations and molecular dynamics simulations and it was consistent with the experimental findings.

Corrosion Inhibition of Carbon Steel by Some Schiff Base Compounds in HCl and H2SO4 Solutions

AbstractThe inhibition power of two Schiff bases on carbon steel corrosion in 1 M HCl and 0.5 M H2SO4 solutions has been investigated using weight loss, Tafel polarization, and electrochemical impedance spectroscopy techniques. The results revealed that increasing the concentration of inhibitors in acidic solutions led to a higher inhibition efficiency. The polarization curves indicated that the Schiff bases acted as mixed inhibitors, affecting both the cathodic and anodic reactions. The adsorption of the inhibitors on the carbon steel surface followed the Langmuir adsorption isotherm, and various adsorption isotherm parameters such as Kads, ΔGads, ΔHads, and ΔSads were determined at room temperature. Furthermore, the effect of temperature on the inhibitors′ performance was examined within the range of 25–45 °C. The corrosion‐related activation energy, pre‐exponential factor (k), activation enthalpy, and entropy were calculated to assess the inhibitors′ behavior. Scanning electron microscopy (SEM) was employed to examine some carbon steel samples, revealing differences in inhibition efficiency attributed to the inhibitors′ chemical structure. The results highlighted the highest inhibition efficiency in H2SO4 medium at 93.4 %, with a corresponding free energy of 39.51 KJ/mol indicating physical‐chemical adsorption of inhibitor molecules. Furthermore, an enthalpy value of −40.6 KJ/mol suggested an exothermic inhibitor absorption process. The findings are presented and discussed in detail.

Design, Synthesis and Evaluation of 8‐(Piperazin‐1‐yl) Imidazo[1,2‐a]Pyrazine Derivatives as Acetylcholinesterase Inhibitors and Antioxidants

AbstractA series of 8‐(piperazin‐1‐yl) imidazo [1,2‐a] pyrazine derivatives were designed and synthesized as acetylcholinesterase inhibitors (AChEIs) and antioxidants for the treatment of Alzheimer's disease (AD). Moreover, the biological evaluation results demonstrated that these synthesized compounds exhibited moderate inhibitory activities toward acetylcholinesterase (AChE) and radical scavenging activities. Among them, the compound with the strongest inhibitory activity against AChE had an IC50 value of 0.55 μM, which was higher than that of galantamine as the reference compound (IC50 value=5.01 μM). The compound with the strongest antioxidant activity had an IC50 value of 57.94 μM, which was lower than that of the ascorbic acid (IC50 value=25.70 μM) as the control drug. Furthermore, the results of molecular docking studies indicated that the compound could simultaneously bind to both catalytic active site (CAS) and peripheral anionic site (PAS) of AChE, which was consistent with the mixed inhibition pattern shown by enzyme kinetic studies. The interaction's stability was also assessed using a conventional atomistic 100 ns dynamics simulation study, which revealed the conformational stability of representative compound in the cavity of the AChE. In addition, the molecular properties of all compounds were predicted online through the SwissADME, and most compounds matched the properties of most orally administered drugs. Based on the biological activity and molecular properties, 8‐(piperazin‐1‐yl) imidazo[1,2‐a] pyrazine derivatives as AChEI were valuable for further development.

Nitrophenylpiperazine derivatives as novel tyrosinase inhibitors: design, synthesis, and in silico evaluations

A novel series of 4-nitrophenylpiperazine derivatives (4a–m) was designed and synthesized as potential tyrosinase inhibitors. Comprehensive characterization using 1H-NMR, 13C-NMR, CNH, and IR techniques was performed for all target compounds. Subsequently, the derivatives were evaluated for their inhibitory activity against tyrosinase. Among them, compound 4l, featuring an indole moiety at the N−1 position of the piperazine ring, exhibited a significant tyrosinase inhibitory effect with an IC50 value of 72.55 μM. Enzyme kinetics analysis revealed that 4l displayed mixed inhibition of the tyrosinase enzymatic reaction. Molecular docking was carried out in the enzyme’s active site to further investigate the enzyme-inhibitor interactions. Based on the findings, compound 4l shows promise as a lead structure for the design of potent tyrosinase inhibitors. This study paves the way for the development of more effective tyrosinase inhibitors for potential applications in various fields.

Chrysophyllum Albidum extract as a new and green protective agent for metal

ABSTRACT Gravimetric measurements and potentiodynamic polarization techniques were employed to investigate the protective performance of the metal in 1 M HCl and 0.5 M H2SO4 solutions by the C. albidum leaf extract at different concentrations (400-1600 mg/L) and time periods (1-4 days). The results showed the highest protection ability of over 96-97%, with inhibition increasing with higher extract concentrations. Polarization studies indicated a mixed inhibition mechanism, reducing both anodic dissolution and cathodic hydrogen evolution rates. Gas chromatography–mass spectrometry (GC–MS) analysis identified major organic constituents in the extract. Thermodynamic data fit the Langmuir isotherm model, suggesting chemisorptive adsorption of inhibitor molecules on the mild steel surface. Computational methods, including density functional theory (DFT), molecular dynamics simulations, and quantum chemical calculations, provided insight into inhibitor-metal interactions and adsorption behaviour at the molecular level. Overall, the study establishes C. albidum leaf extract as an effective, sustainable alternative to commonly used toxic chromate and phosphate inhibitors. It performs competitively even at low concentrations and in environments. The promising green inhibition properties, combined with the extract's nontoxicity and abundance from a natural source, suggest its potential as a cost-effective corrosion protection solution, especially for applications in developing economies.

Glucosidase inhibition and compound identification of stingless bee honey and preserved fruits of Citrus japonica

Food preservation has many benefits, such as increasing shelf life, retaining nutritional values and biological activities. In the current study, total phenolic content (TCP), antioxidant and anti-glucosidase activities, and kinetic of glucose inhibition of stingless bee honey, honey mixed with fruits, and extracts of Citrus japonica were evaluated by measuring color of a reaction using a spectrophotometer. The result showed that high TPC was found in ethanol extract of C. japonica leaves and fruits (26.79 ± 6.94 and 12.79 ± 0.87 mg of gallic acid per g extract), while stingless bee honey revealed the highest antioxidant activity (1/EC50 = 0.2921) and honey mixed with fruits revealed the strongest anti-glucosidase activity (1/EC50 = 1.8181), significantly (P-value <0.05). Kinetic of glucosidase inhibition of honey were found as uncompetitive and mixed competitive inhibition, while the honey mixed with fruits showed mixed competitive inhibition. The FTIR and GC-MS analysis demonstrated the presence of several bioactive compounds. Very strong positive relationship between total phenolic content with GC-MS data was found (r = 0.926, P-value < 0.05). This knowledge confirmed that stingless bee honey and honey mixed with fruits had greater anti-diabatic potential in comparison with the extracts of C. japonica leaves and fruits.

The metabolic activation of pentachlorophenol to chloranil as a potent inhibitor of human and rat placental 3β-hydroxysteroid dehydrogenases

Pentachlorophenol (PCP) is a widely used pesticide. However, whether PCP and its metabolite chloranil have endocrine-disrupting effects by inhibiting placental 3β-hydroxysteroid dehydrogenase 1 (3β-HSD1) remains unclear. The study used in vitro assays with human and rat placental microsomes to measure 3β-HSD activity as well as human JAr cells to evaluate progesterone production. The results showed that PCP exhibited moderate inhibition of human 3β-HSD1, with an IC50 value of 29.83 μM and displayed mixed inhibition in terms of mode of action. Conversely, chloranil proved to be a potent inhibitor, demonstrating an IC50 value of 147 nM, and displaying a mixed mode of action. PCP significantly decreased progesterone production by JAr cells at 50 μM, while chloranil markedly reduced progesterone production at ≥1 μM. Interestingly, PCP and chloranil moderately inhibited rat placental homolog 3β-HSD4, with IC50 values of 27.94 and 23.42 μM, respectively. Dithiothreitol (DTT) alone significantly increased human 3β-HSD1 activity. Chloranil not PCP mediated inhibition of human 3β-HSD1 activity was completely reversed by DTT and that of rat 3β-HSD4 was partially reversed by DTT. Docking analysis revealed that both PCP and chloranil can bind to the catalytic domain of 3β-HSDs. The difference in the amino acid residue Cys83 in human 3β-HSD1 may explain why chloranil is a potent inhibitor through its interaction with the cysteine residue of human 3β-HSD1. In conclusion, PCP is metabolically activated to chloranil as a potent inhibitor of human 3β-HSD1.

Inhibitory Activities of Thai Culinary Vegetables against Key Enzymes Relevant to Diabetes Mellitus and the Kinetics of Enzyme Inhibitions

Diabetes mellitus (DM) is one of the most challenging noncommunicable diseases, as it causes significant costs for medical treatment as well as high morbidity and mortality rates. Dietary plants with antidiabetic properties have been explored as an alternative to synthetic medicines to treat DM because of their safety and nutrition. Hence, the objective of the present study was to determine the inhibitory activities of twenty commonly consumed Thai culinary vegetables against α-glucosidase and α-amylase. All vegetables were extracted using deionized water, ethanol, and hexane at 150 rpm and 30°C for 24 hours. The enzyme inhibitory activities were performed using a colorimetric assay. Diverse results for α-glucosidase and α-amylase inhibitory activities were found for all vegetable extracts. The most potent anti-α-glucosidase activity was obtained from the ethanolic extract of Leucaena leucocephala (Lamk.) de Wit with the half maximal inhibitory concentration (IC50) of 13.39 ± 0.14 μg/mL, followed by the aqueous and ethanolic extracts of Polygonum odoratum Lour with IC50 of 25.60 ± 0.42 and 49.03 ± 0.72 μg/mL, respectively. All the samples exhibited mixed, noncompetitive, and uncompetitive inhibition. It can be concluded that the α-glucosidase and α-amylose inhibitory effects of the investigated extracts may be an indicator of antidiabetic potency, and these extracts might potentially be beneficial as functional components for postprandial hyperglycemia treatment.

BTA@MoS2/hydroxyapatite/ZIF8 self-assembled nanohybrid for designing multi-functional smart anti-corrosion system

For the first time, a three components hybrid nanomaterials consisting of molybdenum disulfide (MoS2), hydroxyapatite (HAp), and zeolitic imidazolate framework8 (ZIF8) was utilized as a novel nanocontainer to build a smart anti-corrosion epoxy coating (Ep coating). This nanocontainer was loaded with Benzotriazole (BTA) to impart self-healing properties to the Ep coating and increase its durability against corrosion. To ensure that the filler was effectively synthesized, characterization tests including X-ray diffraction, FT-IR, BET, and TGA were conducted. EIS and polarization tests, conducted on the extract solution of BTA@MoS2/HAp/ZIF8, showed it had a high potential for reducing the corrosion of metals with a mixed inhibition mechanism. The EIS outcomes for the intact coatings suggested that an Ep coating's lifespan increased by including BTA@MoS2/HAp/ZIF8. Even after seven weeks of immersion in a 3.5% NaCl solution, it was able to keep |Z|f = 0.01Hz above 109.5. FE-SEM and EIS experiments revealed that the Ep coating filled with BTA@MoS2/HAp/ZIF8 exhibited self-healing properties after an artificial scratch creation. Incorporating BTA@MoS2/HAp/ZIF8 into the Ep coating enhanced the coating's adhesion properties and lowered adhesion loss by 78.4%. BTA@MoS2/HAp/ZIF8 could also reduce the diameter of cathodic disbondment by 68%.

A convolutional neural network -VGG16 method for corrosion inhibition of 304SS in sulfuric acid solution by timoho leaf extract

A corrosion inhibition test, coupled with a quantification of in-situ H2 evolution, can be used to evaluate an organic inhibitor such as Timoho leaf extract (TLE). TLE is a biodegradable and effective corrosion inhibitor because of its potential to protect 304SS against sulfuric acid. TLE corrosion inhibitor was studied through systematic electrochemical experiments and morphological characterization, with a concentration range of 0–6g L−1. Convolutional Neural Network (CNN)-VGG16 was one of the machine learning approaches used to classify and predict physical changes in hydrogen gas bubbles. Constituents of the TLE and 304SS surfaces were analyzed by FT-IR and UV–Vis tests. The results suggested that 3 g L−1 TLE inhibitor was able to reduce the corrosion rate by 99.37 %. The TLE's inhibition mechanism on 304SS was mixed adsorption and mixed type inhibitor that followed the Isothermal Freundlich Equation. The prediction model by CNN-VGG16 for corrosion tests at varied inhibitor doses was 96% accurate. SEM tests revealed that TLE constituent adsorption on the 304SS surface had a smooth surface morphology with few degraded spots.

Exploring cinnamon extract’s potential as a green corrosion inhibitor for X65 carbon steel in sulfuric acid: a comprehensive investigation

The effectiveness of cinnamon extract as an environmentally friendly corrosion inhibitor for X65 carbon steel (X65CSt) in a 1 mol/L H2SO4 solution was examined using electrochemical, chemical, and computational techniques. This inhibitor has many advantages, it is safe, environmentally friendly, harmless to human health, and economically feasible. The anticorrosion efficacy rises with rising the concentration of the cinnamon extract and reducing temperature and reaches 95.83% at 450 mg l−1 of cinnamon extract using potentiodynamic polarization. All the investigated methods confirm the anticorrosion ability of cinnamon extract as indicated by the reduced the corrosion current density values and mass loss as well as the greater charge transfer resistance. In addition, the values of the pitting potentials were also transformed in a more noble direction implying the resistance of pitting attack. The polarization technique categorized the cinnamon extract as a mixed inhibitor. The mechanism of inhibition was demonstrated in terms of adsorption of the main components of cinnamon extract onto the surface of X65CSt. of the adsorption of the main components of the cinnamon extract on the surface of the X65CSt and this adsorption is of combined type between both physical and chemical modes, as determined by the computed values of free energy of adsorption, which range between −46.96 and −37.42 kJ. mol−1. The adsorption is exposed to Langmuir isotherm. The four components of cinnamon extract were investigated through density functional theory, Monte Carlo, and Molecular dynamic simulation. The quantum parameters and the adsorption of these components on the Fe(110) reveals that cinnamaldehyde and cinnamic acid inhibitors are more effective as corrosion inhibitors.

Fermentation of millet bran with Bacillus natto: enhancement of bioactivity levels and the bioactivity of bran extract.

Millet bran (MB), a byproduct of millet production, is rich in functional components but it is underutilized. In recent years, researchers have shown that fermentation can improve the biological activity of cereals and their byproducts. This study used Bacillus natto to ferment millet bran to improve its added value and broaden the application of MB. The bioactive component content, physicochemical properties, and functional activity of millet bran extract (MBE) from fermented millet bran were determined. After fermentation, the soluble dietary fiber (SDF) content increased by 92.0%, the β-glucan content by 164.4%, the polypeptide content by 111.4%, the polyphenol content by 32.5%, the flavone content by 16.4%, and the total amino acid content by 95.4%. Scanning electron microscopy revealed that the microscopic morphology of MBE changed from complete and dense blocks to loosely porous shapes after fermentation. After fermentation, the solubility, water-holding capacity, and viscosity significantly increased and the particle size decreased. Moreover, the glucose adsorption capacity (2.1 mmol g-1), glucose dialysis retardation index (75.3%), and α-glucosidase inhibitory (71.4%, mixed reversible inhibition) activity of the fermented MBE (FMBE) were greater than those of the unfermented MBE (0.99 mmol g-1, 32.1%, and 35.1%, respectively). The FMBE presented better cholesterol and sodium cholate (SC) adsorption properties and the adsorption was considered inhomogeneous surface adsorption. Fermentation increased the bioactive component content and improved the physicochemical properties of MBE, thereby improving its hypoglycemic and hypolipidemic properties. This study not only resolves the problem of millet bran waste but also encourages the development of higher value-added application methods for millet bran. © 2024 Society of Chemical Industry.

Versatility of copper-iron bimetallic nanoparticles fabricated using Hibiscus rosa-sinensis flower phytochemicals: various enzymes inhibition, antibiofilm effect, chromium reduction and dyes removal.

Bimetallic nanoparticles (NPs) are considered superior in terms of stability and function with respect to its monometallic counterparts. Hence, in the present study Hibiscus rosa-sinensis flower extract was used to synthesis copper-iron bimetallic nanoparticles (HF-FCNPs). HF-FCNPs was characterized and its applications (biological and environmental) were determined. HF-FCNPs were spherical in shape with high percentage of copper inducted into the NPs. HF-FCNPs inhibited mammalian glucosidases [maltase (IC50: 548.71 ± 61.01µg/mL), sucrase (IC50: 441.34 ± 36.03µg/mL), isomaltase (IC50: 466.37 ± 27.09µg/mL) and glucoamylase (IC50: 403.12 ± 14.03µg/mL)], alpha-amylase (IC50: 16.27 ± 1.73µg/mL) and acetylcholinesterase [AChE (IC50: 0.032 ± 0.004µg/mL)] activities. HF-FCNPs showed competitive inhibition against AChE, maltase and sucrase activities; mixed inhibition against isomaltase and glucoamylase activities; whereas non-competitive inhibition against α-amylase activity. HF-FCNPs showed zone of inhibition of 16 ± 2mm against S. mutans at 100µg/mL concentration. HF-FCNPs inhibited biofilm formation of dental pathogen, S. mutans. SEM and confocal microscopy analysis revealed the disruption of network formation and bacterial cell death induced by HF-FCNPs treatment on tooth model of S. mutans biofilm. HF-FCNPs efficiently removed hexavalent chromium in pH-independent manner and followed first order kinetics. Through Langmuir isotherm fit the qmax (maximum adsorption capacity) was determined to be 62.5mg/g. Further, HF-FCNPs removed both anionic and cationic dyes. Altogether, facile synthesis of HF-FCNPs was accomplished and its biological (enzyme inhibition and antibiofilm activity) and environmental (catalyst to remove pollutants) applications have been understood.