Assessment of Hydrazone Derivatives for Enhanced Steel Corrosion Resistance in 15 wt.% HCl Environments: A Dual Experimental and Theoretical Perspective.

This study evaluates the corrosion inhibition capabilities of two novel hydrazone derivatives, (E)-2-(5-methoxy-2-methyl-1H-indol-3-yl)-N'-(4-methylbenzylidene)acetohydrazide (MeHDZ) and (E)-N'-benzylidene-2-(5-methoxy-2-methyl-1H-indol-3-yl)acetohydrazide (HHDZ), on carbon steel in a 15 wt.% HCl solution. A comprehensive suite of analytical techniques, including gravimetric analysis, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM), demonstrates their significant inhibition efficiency. At an optimal concentration of 5 × 10-3 mol/L, MeHDZ and HHDZ achieve remarkable inhibition efficiencies of 98% and 94%, respectively. EIS measurements reveal a dramatic reduction in effective double-layer capacitance (from 236.2 to 52.8 and 75.3 µF/cm2), strongly suggesting inhibitor adsorption on the steel surface. This effect is further corroborated by an increase in polarization resistance and a significant decrease in corrosion current density at optimal concentrations. Moreover, these inhibitors demonstrate sustained corrosion mitigation over extended exposure durations and maintain effectiveness even under elevated temperatures, highlighting their potential for diverse operational conditions. The adsorption process of these inhibitors aligns well with the Langmuir adsorption isotherm, implying physicochemical interactions at the carbon steel surface. Density functional tight-binding (DFTB) calculations and molecular dynamics simulations provide insights into the inhibitor-surface interaction mechanism, further elucidating the potential of these hydrazone derivatives as highly effective corrosion inhibitors in acidic environments.

Unraveling Bonding Mechanisms and Electronic Structure of Pyridine Oximes on Fe(110) Surface: Deeper Insights from DFT, Molecular Dynamics and SCC-DFT Tight Binding Simulations.

The development of corrosion inhibitors with outstanding performance is a never-ending and complex process engaged in by researchers, engineers and practitioners. The computational assessment of organic corrosion inhibitors' performance is a crucial step towards the design of new task-specific materials. Herein, the electronic features, adsorption characteristics and bonding mechanisms of two pyridine oximes, namely 2-pyridylaldoxime (2POH) and 3-pyridylaldoxime (3POH), with the iron surface were investigated using molecular dynamics (MD), and self-consistent-charge density-functional tight-binding (SCC-DFTB) simulations. SCC-DFTB simulations revealed that the 3POH molecule can form covalent bonds with iron atoms in its neutral and protonated states, while the 2POH molecule can only bond with iron through its protonated form, resulting in interaction energies of -2.534, -2.007, -1.897, and -0.007 eV for 3POH, 3POH+, 2POH+, and 2POH, respectively. Projected density of states (PDOSs) analysis of pyridines-Fe(110) interactions indicated that pyridine molecules were chemically adsorbed on the iron surface. Quantum chemical calculations (QCCs) revealed that the energy gap and Hard and Soft Acids and Bases (HSAB) principles were efficient in predicting the bonding trend of the molecules investigated with an iron surface. 3POH had the lowest energy gap of 1.706 eV, followed by 3POH+ (2.806 eV), 2POH+ (3.121 eV), and 2POH (3.431 eV). In the presence of a simulated solution, MD simulation showed that the neutral and protonated forms of molecules exhibited a parallel adsorption mode on an iron surface. The excellent adsorption properties and corrosion inhibition performance of 3POH may be attributed to its low stability compared to 2POH molecules.

Superior Long-Term Corrosion Inhibition of N80 Steel by New Eco-friendly Hydrazone-Based Compounds in a Simulated Oil Well Acidizing Environment: Establishing the Mechanism at the Molecular Level.

The acid treatment process of production wells is one of the most acid-induced corrosive processes. Corrosion inhibitors are an effective tool to inhibit the acids employed in acidizing treatments. Herein, new eco-friendly hydrazone-based compounds, namely, 2-(4-isobutylphenyl)-N-((1E,2E)-3-phenylallylidene) propanehydrazide (IPP) and N'-cyclohexylidene-2-[4-(2-methylpropyl)phenyl] propanehydrazide (CIP), were prepared through the functionalization of ibuprofen (IBF) and applied for corrosion mitigation of N80 steel in 15 wt % HCl (referred to hereafter as blank). The anticorrosion performance of selected compounds was investigated by employing weight loss (WL), potentiodynamic polarization curves (PPCs), and electrochemical impedance spectroscopy (EIS), complemented by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses. In addition, density functional theory-based tight-binding (DFTB) modeling was conducted to get molecular-level insights into inhibitor-metal bonding. Experimental results revealed excellent long-term corrosion inhibition efficiency at very low concentrations of inhibitors and a mixed-type inhibition process. Numerically, N80 steel polarization resistance increased from 5.51 Ω cm2 in blank to 608.4 and 396 Ω cm2 in blank inhibited with 5 × 10-3 mol/L of IPP and CIP, respectively, equivalent to 99% and 98% inhibition efficiency based on EIS experiments. Besides, SEM and AFM images showed that, after addition to 15 wt % HCl, inhibitors could effectively prevent the acid attack on the N80 steel surface. The fitting of experimental data to adsorption isotherms indicated that inhibitors' adsorption followed the Langmuir isotherm model and mixed physicochemical adsorption on the metal surface. The DFTB simulation revealed that inhibitor molecules can create covalent and physical interactions with iron atoms, which is further confirmed by partial density of states (PDOSs) analysis.

Rapid Sample Screening Method for Authenticity Controlling of Vanilla Flavours Using Liquid Chromatography with Electrochemical Detection Using Aluminium-Doped Zirconia Nanoparticles-Modified Electrode.

A rapid and sensitive technique for frauds determination in vanilla flavors was developed. The method comprises separation by liquid chromatography followed by an electrochemical detection using a homemade screen-printed carbon electrode modified with aluminium-doped zirconia nanoparticles (Al-ZrO2-NPs/SPCE). The prepared nanomaterials (Al-ZrO2-NPs) were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). This method allows for the determination of six phenolic compounds of vanilla flavors, namely, vanillin, p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillyl alcohol, vanillic acid and ethyl vanillin in a linear range between 0.5 and 25 µg g-1, with relative standard deviation values from 2.89 to 4.76%. Meanwhile, the limits of detection and quantification were in the range of 0.10 to 0.14 µg g-1 and 0.33 to 0.48 µg g-1, respectively. In addition, the Al-ZrO2-NPs/SPCE method displayed a good reproducibility, high sensitivity, and good selectivity towards the determination of the vanilla phenolic compounds, making it suitable for the determination of vanilla phenolic compounds in vanilla real extracts products.

Fipronil and Fipronil Sulfone Distribution in Chicken Feathers and Eggs after Oral and Dermal Exposure.

This work aimed to investigate the bio-distribution and the persistence of fipronil and its primary metabolite fipronil sulfone after oral and dermal administration by simulating natural farming conditions. Fipronil and fipronil sulfone detection and quantification were performed in different poultry matrices using an LC-MS/MS method coupled with modified QuEChERS extraction. After oral administration, fipronil was detected in feathers at each sampling time, in eggs for 28 days, and in the internal organs at the end of the experiment. After dermal administration, high levels of fipronil were detected in feathers, accounting for 195.85 ± 8.54 mg/kg, which were reduced by a third after 60 days. No traces of fipronil were detected in the eggs or internal organs. In addition, fipronil sulfone showed remarkable residues in all samples in trial 2. The data obtained confirmed that inappropriate use of unauthorized pesticides can lead to severe contamination of entire poultry farms. The contemporary presence of fipronil sulfone in feathers and eggs associated with the lack of fipronil in eggs suggests recent dermal contamination or past oral contamination. Moreover, simultaneous analysis of hens' feathers and eggs could represent a new method to improve large-scale monitoring programs and animal welfare, limiting their slaughter.

Surface Polymers on Multiwalled Carbon Nanotubes for Selective Extraction and Electrochemical Determination of Rhodamine B in Food Samples.

In this study, we combine magnetic solid phase extraction (MSPE), with the screen-printed carbon electrode (SPCE) modified by a molecular imprinted polymer (MIP) for sensitive and selective extraction and electrochemical determination of Rhodamine B in food samples. A magnetic solid phase extraction (MSPE) was carried out using magnetic poly(styrene-co-divinylbenzene) (PS-DVB) and magnetic nanoparticles (MNPs) synthetized on the surface of multiwalled carbon nanotubes (MWCNTs). An MIP was prepared on the surface of MWCNTs in the presence of titanium oxide nanoparticles (TiO2NPs) modifying the SPCE for the rapid electrochemical detection of Rhodamine B. The MIPs synthesis was optimized by varying the activated titanium oxide (TiO2) and multiwalled carbon nanotubes (MWCNTs) amounts. The MSPE and electrochemical detection conditions were optimized as well. The present method exhibited good selectivity, high sensitivity, and good reproducibility towards the determination of Rhodamine B, making it a suitable method for the determination of Rhodamine B in food samples.

The protection mechanism offered by Heterophragma adenophyllum extract against Fe-C steel dissolution at low pH: Computational, statistical and electrochemical investigations.

An ethanolic extract of Heterophragma adenophyllum (HA) was investigated as a corrosion inhibitor for Fe-C steel in hydrochloric acid. The inhibition effect of the HA extract was examined using weight deterioration, electrochemical impedance spectroscopy (EIS) and polarization techniques. EIS showed enhanced charge transfer resistance with a maximum protection value of ~96% at 600 ppm concentration. Tafel extrapolation results revealed that corrosion was restricted by mixed inhibition. The icorr values reduced considerably from 53.63 µA cm-2 at 100 ppm to 20.11 µA cm-2 at 600 ppm of HA extract. Interaction intensity was further examined through Langmuir, Freundlich, D-R, Frumkin, and Flory-Huggins adsorption isotherms. The computational study, statistical modelling and surface morphology by XPS, AFM, and SEM-EDX, indicated an excellent adsorption capability of HA on Fe-C steel.

Graphene quantum dots for enhancement of fluorimetric detection coupled to capillary electrophoresis for detection of ofloxacin.

A new CE method with fluorescence detection is reported on the determination of ofloxacin in milk samples using graphene quantum dots (GQDs) for sensitivity enhancement. Injection of GQDs prior the standards/sample is crucial to increase the antibiotic fluorescence response. Clean-up and preconcentration steps allowed for a good linear correlation in a concentration range between 50 and 1000 ng/mL for the ofloxacin, detection and quantification limits being 10.7 and 35.5 ng/mL, respectively. Optimal CE conditions for the seven-fluoroquinolone separation method were assessed in terms of buffer type, pH, and voltage. The selective interaction of GQDs with ofloxacin as model analyte was subsequently studied finding a significant sensitivity improvement; therefore, the analytes would be detected at low concentrations by means of a commercial CE device equipped with a multi-wavelength photoluminescence detector. Due to the different maximum emission wavelengths of the target compounds and the limitations shown by the single-wavelength photoluminescence detector coupled to the CE system, we demonstrated the usefulness of the GQD-assisted sensitivity-enhanced CE method to determine ofloxacin in milk samples. This work opens an interesting possibility of using GQDs in separation techniques combined with photoluminescence detectors for lowering sensitivity levels typically provided by the mere device.

Nanostructured hybrid surface enhancement Raman scattering substrate for the rapid determination of sulfapyridine in milk samples.

The fabrication of surface-enhanced Raman spectroscopy (SERS) substrates, which can offer the advantages of strong Raman signal enhancement with good reproducibility, is still a challenge for practical applications. In this work, a simple and reproducible SERS substrate combining the properties of multi-walled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs), is proposed for the determination and quantification of sulfapyridine in milk samples with a concentration range of 10-100 ng mL-1. The Raman signals of sulfapyridine is enhanced at factor of 4394. The procedure presented is capable of detecting and quantifying small quantities of sulfapyridine without implying any preconcentration step, just using an affordable and portable Raman spectrometer. The precision, in terms of repeatability and inter and intermediate precision, was lower than 8% in all cases.

Gas-phase UV absorption spectra and OH-oxidation kinetics of 1H-1,2,3-triazole and pyrazole.

In this work, we report the gas phase UV absorption spectra and the kinetics of the OH-oxidation of 1H-1,2,3-triazole and pyrazole. UV spectra were determined between 200 and 250 nm, at 350 ± 2 K and at pressures between 0.09 and 0.3 Torr. The reported maximal UV absorption cross sections are (cm2 per molecule): σ 206 nm, 1H-1H-1,2,3-triazole = 2.04 × 10-18 and σ 203 nm, pyrazole = 5.44 × 10-18. The very low absorption capacity of these compounds beyond 240 nm indicates that their atmospheric photodissociation is negligible. The OH-oxidation of these species was performed in an atmospheric simulation chamber coupled to an FTIR spectrometer and to a GC/MS over the temperature range 298-357 K and at atmospheric pressure. Experiments were conducted in relative mode using benzaldehyde, trans-2-hexenal and heptane as references. The obtained rate constants at 298 K were (×10-11 cm3 per molecule per s): k(OH + 1H-1,2,3-triazole) = 2.16 ± 0.41; k(OH + pyrazole) = 2.94 ± 0.42. These results were compared to those available in the literature and discussed in terms of structure-reactivity and temperature dependency. Their tropospheric lifetimes with respect to reaction with OH radicals were then estimated.

Magnetic nanocellulose from olive industry solid waste for the effective removal of methylene blue from wastewater.

The work shown in this article demonstrate a novel example of converting olive industry solid waste (OISW) into a magnetic cellulose nanocrystalline (MNCs) to serve as selective magnetic sorbents for methylene blue. Olive industry solid waste contains about 40% cellulose. The cellulose was extracted in a powder form from olive industry solid waste by subjecting it to a multistep pulping and bleaching process. The extracted powder cellulose was then converted to nanocrystalline cellulose (NCs) by acid hydrolysis. The NCs were then treated with a solution of FeCl3.6H2O, FeSO4, and H2O by a colloidal suspension method which produced free-flowing porous MNCs. The produced MNCs are characterized by several spectroscopic and analytical techniques such as SEM, TEM, XRD, FTIR VSM, and TGA. The efficiency of the three polymers cellulose powder, NCs, and MNCs toward extracting methylene blue (MB) from water was evaluated. Cellulose powder and NCs showed acceptable tendency for methylene blue. However, MNCs showed excellent extraction efficiency toward MB. The thermodynamic studies revealed a spontaneous adsorption of MB by MNCs at various temperatures. The spontaneous adsorption could be attributed to the electrostatic interaction and H-bonding between MNCs and MB. However, the interaction between cellulose, NCs, and MB is limited to the H-bonding.

Capillary electrophoresis method for the discrimination between natural and artificial vanilla flavor for controlling food frauds.

A capillary electrophoresis method was developed for the determination of coumarin (COUM), ethyl vanillin (EVA), p-hydroxybenzaldehyde (PHB), p-hydroxybenzoic acid (PHBA), vanillin (VAN), vanillic acid (VANA) and vanillic alcohol (VOH) in vanilla products. The measured concentrations are compared to values obtained by liquid chromatography (LC) method. Analytical results, method precision, and accuracy data are presented and limits of detection for the method ranged from 2 to 5 µg/mL. The results obtained are used in monitoring the composition of vanilla flavorings, as well as for confirmation of natural or non-natural origin of vanilla in samples using four selected food samples containing this flavor.

Dispersed synthesis of uniform Fe3O4 magnetic nanoparticles via in situ decomposition of iron precursor along cotton fibre for Sudan dyes analysis in food samples.

Fe3O4 magnetic nanoparticles, with a negative charge surface, are known to have efficient adsorbent properties, but they tend to be agglomerated into larger aggregates or flocs, which can cause loss of specific area. The addition of cotton fibre, as a stabiliser in preparation of the Fe3O4 nanoparticles, is able to efficiently reduce particle aggregation, and thus, effective particle size, resulting in much greater specific surface area and adsorption sites. Fe3O4 nanoparticles synthesis was accomplished by in situ high-temperature decomposition of the precursor ferric ion in the presence of cotton fibre and ethylene glycol solvent. The morphology of Fe3O4 nanoparticles was characterised by field emission scanning electron microscopy and X-ray diffraction, which confirmed that the magnetic nanoparticles are highly dispersed. These Fe3O4 nanoparticles were used for clean-up and pre-concentration of Sudan dyes in chilli and hot red sauces, prior to their determination by capillary liquid chromatography diode array detection. A comparative study of analyte pre-concentration was conducted with magnetic nanoparticles prepared with and without cotton fibre showing that both solid phases adsorb the analytes, but higher recoveries were obtained when using cotton fibre which therefore was selected for extraction of Sudan dyes.

Antifungal effectiveness of fungicide and peroxyacetic acid mixture on the growth of Botrytis cinerea.

In the attempt to reduce the negative impacts of chemical pesticides on environment and consumer's health, a new plant treatment practice minimizing the amount of pesticides needed during pests and diseases treatments has been developed. Our approach is based on combining the biocide effects of fungicide with the peroxyacetic acid (PAA) one. In this paper, we focused on the in vitro study of the antifungal activity of this combination against Botrytis cinerea, the most redoubtable threat of tomatoes plants in Morocco. First, different concentrations of a peroxyacetic acid product (PERACLEAN®5) and two commercially available fungicides SWITCH and SIGNUM were tested separately for their inhibitory effects on the mycelial growth and spores germination of B. cinerea. 100% inhibition of fungal growth was achieved using 16.77 and 14.47 µg/ml of SIGNUM and SWITCH respectively and 1.5% of PERACLEAN®5. When combined with 0.5% of the peroxyacetic acid mixture (PERACLEAN®5), the pesticides 100% effective concentrations decreased to 0.5 µg/ml for both pesticides. Hence, this approach allowed us to suppress the pathogen while minimizing the amounts of applied fungicides by more than 95%.

Magnetic/non-magnetic argan press cake nanocellulose for the selective extraction of sudan dyes in food samples prior to the determination by capillary liquid chromatograpy.

Two methods for the determination of Sudan dyes (Sudan I, Sudan II, Sudan III and Sudan IV) in food samples, by solid phase extraction - capillary liquid chromatography, are proposed. Both methods use nanocellulose (NC) extracted from bleached argan press cake (APC), as a nano-adsorbent recycled from an agricultural waste material. One of the methods involves the dispersion of NC in food sample extracts, along with the waste and eluents being separated by centrifugation. In the other method, NC was modified by magnetic iron nanoparticles before using it in the extraction of Sudan dyes. The use of a magnetic component in the extraction process allows magnetic separation to replace the centrifugation step in a convenient and economical way. The two proposed methods allows the determination of Sudan dye amounts at the 0.25-2.00µgL-1 concentration range. The limit of detections, limit of quantifications and standard deviations achieved were lower than 0.1µgL-1, 0.20µgL-1 and 3.46% respectively, when using NC as a nano-adsorbent, and lower than 0.07µgL-1, 0.23µgL-1 and 2.62%, respectively, with the magnetic nanocellulose (MNC) was used. Both methods were applied to the determination of Sudan dyes in barbeque and ketchup sauce samples, obtaining recoveries between 93.4% and 109.6%.

A comparative study of electrochemical oxidation of methidation organophosphorous pesticide on SnO2 and boron-doped diamond anodes.

BACKGROUND: Electrochemical oxidation considered to be among the best methods in waste water desalination and removing toxic metals and organic pesticides from wastewater like Methidathion. The objective of this work is to study the electrochemical oxidation of aqueous wastes containing Methidathion using boron doped diamond thin-film electrodes and SnO2, and to determine the calculated partial charge and frontier electron density parameters. RESULTS: Electrolysis parameters such as current density, temperature, supporting electrolyte (NaCl) have been optimized. The influences of the electrode materials on methidathion degradation show that BDD is the best electrode material to oxidize this pesticide organophosphorous. Energetic cost has been determinate for all experiments. The results provide that 2 % of NaCl, 60 mA cm(-2) and 25 ºC like the optimized values to carry out the treatment. For BDD the achieved Chemical Oxidation Demand reduction was about 85 %, while for SnO2 it was about 73 %. The BDD anode appears to be the more promising one for the effective electrochemical treatment of methidathion. Finally the theoretical calculation was done by using the calculation program Gaussian 03W, they are a permit to identify the phenomena engaged near the electrode and to completely determine the structures of the products of electrochemical oxidation formed during the degradation and which they are not quantifiable in experiments because of their high reactivity. CONCLUSIONS: The comparison of the results relating to the two electrodes indicates that these materials have a power to reduce the quantity of the organic matter in the electrolyzed solution. But the speed of oxidation of these compounds is different according to the materials of the electrodes used. Graphical abstract:Structural of methidathion [O,O-dimethyl-S-(5-methoxy-1,3,4-thiadiazolinyl-3-methyl) dithiophosphate] used for study the electrochemical oxidation.

Crystal structure of (1E,1'E)-N,N'-(ethane-1,2-di-yl)bis-[(pyridin-2-yl)methanimine].

The whole mol-ecule of the title compound, C14H14N4, is generated by twofold rotation symmetry. The twofold axis bis-ects the central -CH2-CH2- bond and the planes of the pyridine rings are inclined to one another by 65.60 (7)°. In the crystal, there are no significant inter-molecular inter-actions present.

Use of molecular and in silico bioinformatic tools to investigate pesticide binding to insect (Lepidoptera) phenoloxidases (PO): insights to toxicological aspects.

In the present work, the promising bioinformatic tools, based on structure-affinity analysis, allowed to screen several pesticides supposed to bind to the insect immune Phenoloxidases (PO). First, the binding of aminoparathion, a reference compound, to the PO was structurally (3D) validated in accordance with previous reports. Second, using the same docking conditions, a range of pesticides was checked for their binding ability to the crystal 3D structure (PDB 3HSS) of the insect Manduca sexta (Lepidoptera) PO. The obtained data showed that many of the tested pesticides were able to bind, in silico, to M. sexta PO. The combination of in vitro (chemical and biochemical) and in silico (automated docking) approaches was found advantageous to elucidate the behavior of phenolic pesticides as substrate-analogues when binding to the active site of insect POs. Our findings emphasize new ecotoxicological aspects of pesticide residues in the agro-chemical and environmental circles.

Detection of argan oil adulteration with vegetable oils by high-performance liquid chromatography-evaporative light scattering detection.

Triacylglycerol profiles were selected as indicator of adulteration of argan oils to carry out a rapid screening of samples for the evaluation of authenticity. Triacylglycerols were separated by high-performance liquid chromatography-evaporative light scattering detection. Different peak area ratios were defined to sensitively detect adulteration of argan oil with vegetable oils such as sunflower, soy bean, and olive oil up to the level of 5%. Based on four reference argan oils, mean limits of detection and quantitation were calculated to approximately 0.4% and 1.3%, respectively. Additionally, 19 more argan oil reference samples were analysed by high-performance liquid chromatography-refractive index detection, resulting in highly comparative results. The overall strategy demonstrated a good applicability in practise, and hence a high potential to be transferred to routine laboratories.

Capillary electrophoresis coupled to evaporative light scattering detection for direct determination of underivatized amino acids: application to tea samples using carboxyled single-walled carbon nanotubes for sample preparation.

An improved and efficient method for the determination of underivatized amino acids based on the use of CE coupled to evaporative light scattering detector (ELSD), involving carbon nanotubes, was successfully developed. Carboxyled single-walled carbon nanotubes were used for the first time to perform the clean-up of the analyzed samples, which were afterwards analyzed by CE-ELSD. White tea samples were used to demonstrate the usefulness of the CE-ELSD coupled methodology. A suitable interface, based on a triple tube design sprayer, was developed and successfully used for coupling both instruments. Parameters affecting the separation and determination, including the elimination of interferences, were studied and properly optimized. Under the optimized conditions good resolution was achieved for the separation of seven amino acids. The precision of the method, expressed as RSD, was found within the 3.5-5.3% range. The LOD obtained for the proposed method were in the 1.2-2.1 pg range and the LOQ, were in the 2.0-11.5 pg range, with injection pressure of 5 KPa for 20 s (15.3 nL). This method is simple, rapid, and selective compared with other conventional techniques.