As the most crucial choice in the heavy-duty protective coating industry, epoxy-based coatings suffer from insufficient toughness and impermeableness. So in this study, a reliable method that is, in turn, easy to be scaled up is designed and proposed. Through this method, a significantly toughened and mechanically improved epoxy nanocomposite film is suggested. This film is based on poly(amidoamine)-grafted (PAMAM) graphene oxide (GO). GO is synthesized and then modified through two consecutive steps; first, silane-grafted GO producing SiGO and second polyamidoamine (PAMAM)-grafted SiGO leading to HbpSiGO. FT-IR, TGA, and XRD results confirm a successful functionalization of the GO flakes. Dynamic mechanical thermal analysis (DMTA) results reveal that the nanocomposite film based on HbpSiGO possesses higher storage modulus (50%), elevated glass transition temperature (18%), and higher cross-linking density (237%) compared to unfilled epoxy. According to tensile testing, HbpSiGO nanocomposite shows an increment in work of fracture (148%), elongation at break (52%), and maximum stress (68%) in comparison with neat epoxy.
In this study, the organic coating of epoxy zinc-chromate (E) and the two-layer coating of epoxy zinc-chromate-polyurethane (PU-E) was coated on the steel substrate using the spraying method. Then, their corrosion resistance was compared using electrochemical impedance spectroscopy (EIS) and dynamic polarization tests. Comparison of corrosion properties using parameters of, phase angle at a maximum frequency (100kHz), and breakpoint frequency (fb) were performed during 2, 4, and 8 weeks. A comparison of these three parameters showed that the corrosion resistance of the PU-E coating was higher than the E coating due to the behavior of the polyurethane coating barrier as well as the active protective behavior induced by the chromate pigments which was distributed on the epoxy coating. According to the test results, E and PU-E coatings had good hardness and scratch resistance and were resistant to pencil scratches with H and F hardness, respectively. The salt spray test for the two-layer coating showed no qualitative change, damaged area, blistering/delamination, or corrosion products on the coated sample. The results showed that both coatings were suitable candidates for use in various industries, including marine and power industries, and other industries that suffered from corrosion problems.
The corrosion inhibition performance of 1-phenyl-2-(1-phenylethylidene) hydrazine (PPEH) and 1-(1-(4-methoxyphenyl)ethylidene)-2-phenylhydrazine (MPEH) for mild steel (MS) in (1.0 M) hydrochloric acid was investigated based on weight loss measurements. Conditions that affect the corrosion inhibition efficiency, such as concentration, immersion time, the chemical structure of Schiff bases, and solution temperature, were possessed in the current study.The experimental findings demonstrated that PPEH is less than MPEH. In addition, (0.005 M) PPEH protected the tested surface by (83.8%) at (30 oC), while (0.004 M) MPEH afforded (87.2%) protection.The inhibition efficiencies of PPEH and MPEH are (83.8%) and (95.1%), respectively, at a concentration of (0.005 M) at (5 h), exposure time.The efficiency of corrosion inhibition of MPEH is greater than PPEH in the hydrochloric acid environment due to the electron-donating group (methoxy group) substituted to the para-position of the phenyl ring of MPEH. The desorption process of both studied inhibitors upon the (MS) surface follows the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) photographs proved the protective layer's formation upon the (MS) surface.
Polarization and electrochemical impedance spectroscopy (EIS) were employed for investigating the behavior of clemastine drug on the corrosion protection of carbon steel in 0.5 M H2SO4 solution which was enhanced by increasing the clemastine concentration in acid solution. As evidenced by polarization data, clemastine behaved as a mixed-type inhibitor and retards both anodic and cathodic processes. Adsorption of clemastine on carbon steel in acid solution obeyed the Langmuir adsorption isotherm. A reasonable correlation was observed between the ∆Goads values obtained from EIS and potentiodynamic polarization measurements. The calculated ∆Goads values of clemastine confirmed comprehensive adsorption that is a combination of physical and chemical adsorption. The electronic properties of clemastine were calculated via density functional theory (DFT) approach to establish the relationship between the inhibitive effect and molecular structure of the clemastine. According to the obtained quantum chemical parameters, clemastine showed higher EHOMO, lower EHOMO, lower energy gap, and higher dipole moment than some inhibitors earlier reported as good corrosion inhibitors.
A novel turn-on nano chemosensor for Hg2+ was developed based on CoFe2O4@SiO2 nanocomposite. Cobalt nano ferrite particles were decorated with 1,8-naphthalimide dye conjugated with rhodamine dye. It was characterized using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), FT-IR techniques. A fluorescence enhancement was observed upon binding Hg2+ to two core chromogenic dyes. No significant change in the fluorescence intensity was observed in the presence of other metal ions. The results showed that the functionalized nanocomposite CoFe2O4@SiO2/NR exhibited selective 'turn-on' fluorescent enhancements with Hg2+. Also, the company of magnetic CoFe2O4@SiO2 nanocomposite (with a wide range of applications such as biomedicine, magnetic fluids, magnetic energy storage) and catalysis facilitates the magnetic separation of the Hg (II) from the solution. Nano chemosensor exhibits high selectivity, high sensitivity and fast response to trace mercury ions. Designed nanosensor successfully applied for Hg2+determination at real samples with a linear range of 0.04-0.76 μM of Hg2+ ions. It was successfully applied for the determination of mercury ion in real samples of tap water. It seems that the presence sensor is a suitable candidate for the detection of trace mercury ion in biomedical samples like a human serum. Also, it is fast and easy control for monitoring of water toxicity of pollutant industries.
Recently, there has been an increasing interest towards the finishing of textiles (fibers, yarns, fabrics and nonwovens) using eco-friendly technology, which can achieve a wide range of functional properties and environmental benefits. This study is related to a modern eco-friendly bleaching technology that relies on Ultraviolet/O3 radiation of poly(lactic acid) fabric through simple technique. The effects of Ultraviolet/O3 radiation along with the pretreatments with distilled water, hydrogen peroxide, and hydrogen peroxide/sodium silicate solutions on the bleaching of the poly(lactic acid) fabrics were examined using UV-Visible and reflectance spectral method and the results were compared with that of virgin untreated samples. Ultraviolet/O3 bleaching routes were screened to obtain desired whiteness index (WI), tint factor (Tw), lightness/darkness (L*), redness/greenness (a*), yellowness/ blueness (b*), chroma (c*) and hue (h˚) of the bleached poly(lactic acid) fabrics. The optimal properties of the bleached poly(lactic acid) knitted fabric could be obtained at Ultraviolet/O3 irradiation for 80 min on the fabrics which pre-impregnated in a hydrogen peroxide solution with a wet pick up of 70 %, pressure of 1.1 bar and speed of 2 m/min. (Ultraviolet/O3/H2O2 bleaching system). The Ultraviolet/O3/H2O2 bleached fabric showed the best colorimetric properties (WI: 87.7, : -0.1, L*:94.227, a*:-0.106, b*:0.294, c*:0.2512, h˚: 98.6551). Moreover, the reflectance of this sample has increased significantly in the range of 400-450 nm which leads to a glossy withe shade on the fibers. The SEM images presented that after Ultraviolet/O3/H2O2 bleaching process, some fractures with nano scale size (about 130 nm) are formed on the poly(lactic acid) fabric surface. The ATR-IR spectrum of Ultraviolet/O3/H2O2 bleached poly(lactic acid) fibers displays more intense C–C–O absorption bands (1161 cm-1).
In this work, a new Schiff base, namely 2-(2,4-dimethoxybenzylidene)-N-phenylhydrazinecarbothioamide (DP), was synthesized and fully characterized by some spectroscopical techniques (Fourier Transform Infrared (FT-IR), and Nuclear Magnetic Resonance (1H-NMR and 13C-NMR) in addition to micro elemental analysis-CHN. The newly synthesized corrosion inhibitor was evaluated for its corrosion inhibition performance on mild steel coupons in 1 M hydrochloric acid solution by using gravimetric techniques. The experimental findings of weight loss measurements revealed that the inhibition efficiency increased with the DP concentration and reached a maximum value of 94.8% at the 0.005 M concentration but decreased with reducing temperature (at temperatures ranging from 303 to 333 K). Moreover, the significant inhibition efficiency and the value of ΔGo indicated that DP participates in Chemisorption and Physisorption on the mild steel surface. The adsorption process of the synthesized inhibitor on a mild steel surface follows Langmuir adsorption isotherm. The uninhibited and inhibited surface morphology of the mild steel coupons was investigated using scanning electron microscopy (SEM).
In the present study, the corrosion protective ability of the sol-gel based composite coatings containing two-different types of the cationic/anionic based inhibitors loaded containers. For this purpose, the NaY zeolite and Zn-Al Layered double hydroxides (LDHs) containers were loaded with Ce3+ cations and 2- mercaptobenzothiazole (MBT) separately. The morphology and composition of the constructed micro/nanocontainers were studied using analytical methods, confirming the successful loading of the inhibitors. In this study, the Ce3+/MBT inhibitors were successfully introduced into the LDH/NaY-based zeolite containers.Results evidenced that the combination of the two inhibitors has a constructive effect on the active protection of the AA2024-T3 sheets. SEM micrographs of the unfilled LDH and stupefaction with MBT show that the prepared LDHs have sheet-like morphology. The addition of single-inhibitor filled containers to the sol-gel hybrid coating, and water-based epoxy coating provided active protection for the AA2024-T3 coated substrate. However, the combination of the filled containers with the inhibitor in the above-mentioned coatings resulted in the improvement of the active protection of the substrate, which confirms the synergy between the particles. The NaY containers loaded with the Ce3+ resulted in a significant increase of the |Z|0.01 Hz of the gel-sol hybrid coatings, which indicates the formation of a stable oxide layer with higher resistance. Whereas the |Z|0.01 Hz of the hybrid sol-gel coatings loaded with LDH-MBT were in the same range as the NaY-Ce loaded coatings, containing NaY-Ce and LDH-MBT, showed the highest |Z|0.01 Hz values that indicate the synergy between the inorganic (Ce3+) and organic (MBT) inhibitors in sol-gel hybrid coatings.
Inhibition effects of 5-aminosalicylic acid (5-ASA) on the under deposit corrosion of X60 steel in 3.5 % NaCl solution saturated with CO2 have been investigated by the techniques of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The sand-covered electrode was prepared by covering the X60 steel electrode with a layer of silica sand. The increase of 5-ASA concentration up to 600 ppm led to increasing the inhibition efficiency of X60 steel against under deposit corrosion in the brine solution. The Langmuir isotherm can describe the adsorption behavior of 5-ASA on the surface of the steel. Measurements of potentiodynamic polarization indicated that 5-ASA is an anodic inhibitor. The effects of temperature on the under deposit corrosion behavior of carbon steel were studied both in the absence and presence of 600 ppm 5-ASA. The enthalpy of the 5-ASA adsorption was obtained from the temperature dependence of the corrosion inhibition process. A reasonable agreement was observed between the IE values resulted from the Tafel and the EIS techniques. The electronic properties of 5-ASA were calculated in both the gas phase and the aqueous phase by a density functional theory (DFT) approach to establish the relationship between the inhibitive effect and molecular structure of 5-ASA.
Novel modified coumarin bearing thiosemicarbazide pendant moiety prepared by the reaction of 3-(6-methyl-2-ketoquinoline)methanal with thiosemicarbazide through a condensation reaction. The synthesized coumarin namely 2-((6-methyl-2-ketoquinoline-3-yl)methylene) hydrazinecarbo-thioamide (MKMHCT) was characterized using spectroscopic techniques (proton and carbon 13 nuclear magnetic resonance and Fourier transform infrared). The corrosion inhibition of mild steel in 1 M hydrochloric acid solution by MKMHCT was investigated using the gravimetric method, scanning electron microscopy, and quantum chemical calculations. The obtained findings indicated that MKMHCT can inhibit the mild steel corrosion in a hydrochloric acid environment. The highest inhibition efficiency obtained from gravimetric techniques was 95.84% at the inhibitor concentration of 0.005 M. The adsorption of the studied inhibitor molecules on the mild steel surface was found to obey the Langmuir adsorption isotherm. Density functional theory (DFT) revealed an excellent correlation with experimental inhibitive performance. The frontier molecular orbital energies, i.e., Highest Occupied Molecular Orbital (HOMO), Lowest Unoccupied Molecular Orbital (LUMO), and other parameters were in harmony with methodological findings. Mulliken charges indicated that the inhibitor molecules are adsorbed on the surface of mild steel via coordination bonds between the iron atoms on the mild steel surface and the pairs of electrons of the nitrogen, oxygen and sulfur atoms.
New corrosion inhibitors, namely N'-acetyl-4-pyrrol-1-ylbenzohydrazide (NAPB), were synthesized by the reaction of 4-pyrrol-1-ylbenzohydrazide with acetic anhydride. NAPB was characterized by FTIR and NMR spectroscopy. Weight loss measurement was used to evaluate the corrosion inhibition of Low-carbon steel in a 1 M hydrochloric acid medium. The inhibition efficiency (IE%) increased as NAPB concentration increases and decreases as the solution temperature increases. The inhibition efficiency reached 94.6 % at the optimum concentration (500 ppm) of NAPB. The scanning electron microscopy technique proved the formation of a protective layer from NAPB molecules as corrosion inhibitors on the Low-carbon steel surface. The adsorption isotherm of NAPB molecules on the surface of Low-carbon steel was confirmed to follow the Langmuir adsorption isotherm. Further, through quantum chemical calculations using density functional theory (DFT), the importance of inhibition performance and molecular structure of an inhibitor has been theoretically investigated. Both experimental and theoretical findings are consistent with one another.
Interaction of pharmaceutically active drug Cefixime on mild steel surface in 0.5M sulphuric acid solution was studied using gravimetric analysis techniques, Polarization techniques i.e. Polarization resistance, tafel polarization and Electrochemical Impedance Spectroscopy (EIS) techniques. It shows more than 96% of corrosion inhibition efficiency at ambient temperature of 308oK on mild steel surface with the 4.0×10-4 M inhibitor concentration. Gravimetric studies were also conducted at various temperature and concentration range of the testing solution to justify their range of applicability at various practical conditions. And It is found very much suitable for their workings at the normal temperature and lower acid concentration ranges. Adsorption parameters and thermodynamic parameters were calculated from gravimetric analysis data obtained at different temperature and concentration range and reveals that the inhibitor follows the physical adsorption mechanism. Adsorption of Cefixime molecule is governed by Langmuir's adsorption isotherm. Inhibition of Cefixime on surface of mild steel is supplemented by atomic force microscopy, which reveals that the inhibited surface has less roughness than the uninhibited surface.
This work aims to study the photodegradation of Direct Blue 199 dye. The investigation was performed using titanium dioxide-based films immobilized on a polymethyl methacrylate (PMMA) polymer, by a promising low coast technique. The characterization of the films by X-ray diffractometry, fourier transform infrared spectroscopy, scanning electron microscopy, UV-Visible transmittance, and fluorescence spectroscopy revealed the deposition of 13.76% by mass of TiO2 with excellent adhesion to the polymer surface. However, the evaluation of the influence of three parameters (pH, initial TiO2 concentration, H2O2 concentration) on the efficiency of color removal in aqueous solution under UV irradiation on suspended semiconductors, have been performed using the response surface methodology based on experimental design. We therefore found the following optimum conditions: pH= 8, [TiO2] = 1369.29 mg.L-1, [H2O2] = 40 mmol.L-1 which led to a discoloration efficiency of 85 %. The results were then used to evaluate the performance of the prepared photocatalyst films, which showed a strong capacity to absorb the dye due to the appearance of pores relative to the preparation procedure, in addition to their catalytic effect. The kinetic of decolorization under optimum conditions was well fitted to the pseudo-first-order kinetic model.
This paper employs the electrochemical current noise (ECN) and electrochemical impedance spectroscopy (EIS) techniques to better evaluate the dissolved O2 concentration on the passive oxide film of AA6162 Al alloy. The ECN measurements were done on the asymmetrical electrodes with different sizes (2-200 mm2) after 5 min from immersion in each of 0.4% NaCl, 0.4% NaCl + 0.1% NaNO2 and 3.5% NaCl solutions containing different O2 concentrations (5-25 ppm). EIS measurements were used to calculate the thickness of the passive oxide film. In dilute NaCl solution, the dissolved oxygen played an active role with an increase in oxygen concentration up to 15 ppm, while with further increase of oxygen concentration it acted as a passive factor to decrease the corrosion activity. With increasing the concentration of oxygen from 5 to 25 ppm, in the concentrated NaCl solution, the oxide film thickness decreased as an evidence of the active role of the oxygen reduction reaction. The behavior of nitrite-containing NaCl solution was in accordance with the property of nitrite ion which assists the formation of the passive film according to the adsorption theory.
Multiple poly(vinyl butyral) (PVB) nanocomposite films embedded with Co3O4, CuO, NiO, TiO2, and Cr2O3 nanoparticles (NPs) were prepared using the casting method. A loading ratio of 0.001 wt.% of the nanoparticles was used to synthesize the nanocomposite films, where the process was conducted at room temperature and the films’ electrical properties were analyzed at a frequency of 1-3 MHz. The studied properties include the dielectric constant (real and imaginary parts (Ɛ' and Ɛ'', respectively)), conductivity (ϬAC), loss factor (tan δ), surface energy loss function (SELF), and volume energy loss function (VELF). A significant improvement in the mentioned properties was achieved once the films were filled with the NPs comparing with the blank PVB. Furthermore, the surface morphology of PVB nanocomposites films was examined using field emission scanning electron microscopy (FESEM) and energy dispersive x-ray (EDX) spectroscopy. Overall, findings revealed that PVB nanocomposite films showed a higher conductivity compared to the PVB blank. Thus, these types of nanocomposite films could be utilized in photovoltaics, optical devices, and military apparatuses due to their extraordinary features, such as radiation resistivity.
Invention new thin films nano-coating to obtain high-level performance spectrally selective surfaces to enhance solar energy by spin and casting methods, thin films coating are deposited by these techniques on aluminum and glass substrates that were pre-cleaned. Nanocomposite thin film coating comprising (Co3O4:Cr2O3) and carbon to gain an economical coating. The coating has a high absorptivity of solar energy. Nanomaterials have been used in various concentration ratios to dope carbon, and Energy Dispersive Analysis (EDX) was used to determine carbon ash's chemical composition; SEM measured its practical size. Optical properties have been studied by the UV-Visible Spectra and reflectivity tests in a range from 250-1300 nm at room temperature. Absorbance coefficient, transmittance, reflectance, skin depth, optical density, optical energy gap (Eg), and Urbach energy of nanocomposite thin films have also been specified. The Eg of doped C has been measured with different concentration ratios of (Co3O4:Cr2O3) such as sample F (0.5:2.5/7), sample G (1:2/7), sample H (1.5:1.5/7), the sample I (2:1/7), and sample K (2.5:0.5/7) wt. %, the concentration of C is fixed for all samples (7) wt. %. The results revealed that the Eg is ranged (2.9-3.9 eV) and the absorptivity in the ranged (88-93.2 %) for all doped samples. The absorptivity values of nanocomposites are very close to semiconductor elements, which have high absorptivity to the wavelength intensity. The synthesized coating will be used over a flat plate collector as a trap to absorb solar energy for a highly feasible selective surface.
In this study, for the first time, an electrospun nanofibrous (Nfs) composite was prepared from Zein biopolymer and graphene oxide (Ze-GONfs). The effective parameter in electrospining preparation of zrin-GO nanofiber was the amount of zein. Highly mechanical stable membranes were obtained using 30% w/v in glacial acetic acid. The fiber diameter distribution was in the range of 41–50 nm (zein), 31–40 nm (0.5% GO), 29–39 nm (1.0% GO), and 28–37 nm (1.5% GO). The structural morphology of the nanofibrous composites were characterized using Fourier transform infrared, scanning electron microscope (SEM) and X-ray diffractometer. As an application of the prepared biopolymeric nanofibrous, the removal of malachite green (MG) and methylene blue (MB) (as cationic industrial dyes) from aqueous medium using Ze-GONfs was investigated as a model. The effect of various parameters such as solution pH, adsorbent dosage, dye concentration, time and temperature were evaluated by the Ze-GONfs. Detailed analysis of the adsorption kinetics showed that the adsorption process followed a pseudo-second-order model. The adsorption isotherm was best fitted by the Langmuir model. The thermodynamic results showed that MB and MG adsorption onto the Ze-GONfs was endothermic and spontaneous.
The optical properties for pure poly(vinyl chloride) (PVC) were doped by nanomaterials of CuO and CoO with various concentration ratio has been applied on glass substrate. The result obtained were shown the thin film coating of CuO and CoO has a high absorptive of solar energy.Optical properties have been Measure by the UV-Visible Spectra and reflectivity tests in the wavelengths range (200-1200nm) at room temperature. The transmittance, absorbance, refractive index, extinction factor and energy gap were used to study different optical properties. Optical energy gap (Eg), absorbance coefficient, reflectance, transmittance, skin depth, optical density. These properties have been increased by doping PVC with nanomaterials. The energy gaps were calculated and their values have been investigated. The energy gap value was found to be decline from 5.15 eV for pure PVC to 2.2 eV and 2.1 eV for PVC/CuO and PVC/CoO respectively of the nanocomposites. The optical data was interpreted and analyzed by phonon theory to assist in the direct transition of electrons, it is clear that the energy gap is influenced by nanomaterials used in doping poly(vinyl chloride), then the present results depend on the optical properties of pure and poly(vinyl chloride) films adopted with nanomaterials. The AFM has been used to determine the surface morphology of the thin films and the distribution of nanoparticles which was inspected in three dimensional images.
The corrosion inhibition of API 5L X60 pipeline steel in oil well acidizing fluid stimulated with 1.0 M HCl by Tranexamic Acid (TXA) was investigated using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and the conventional gravimetric or weight loss (WL) techniques at temperatures ranging from 303 to 323 K. Surface morphological analysis was carried out using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). The compound showed high inhibition activity with 98.9% inhibition efficiency at 3.0 g/L concentration of TXA. Polarization analysis indicates that TXA acts as mixed-type inhibitor. The observed decrease in double layer capacitance and an increase in charge transfer resistance obtained from EIS analysis confirmed that TXA performed well as a corrosion inhibitor for X60 steel in 1.0 M HCl medium, ascribed to the adsorption of Tranexamic Acid molecules onto the X60 steel surface. Weight loss analysis showed that inhibition efficiency is increased with the increase of TXA concentration and exposure time while decreased with temperature rise. The adsorption of TXA onto the surface of the X60 steel obeys Langmuir adsorption isotherm. SEM-EDX analysis affirmed the formation of protective adsorbed film of Tranexamic Acid onto the steel surface.
This paper describes the changes in TiO2/SiO2 nanolayers properties induced by Ultraviolet- visible spectroscopy (UV) irradiation in terms of hydrophilicity/photocatalycity. The TiO2/SiO2 nano particles were synthesized by the sol-gel method and deposited on soda-lime glass by dip-coating. X-ray diffraction (XRD) of the TiO2 particles showed that the nano-particles were crystallized in anatase crystal structure with a crystallite size of ~12 nm. The morphology and surface roughness of TiO2 nanolayer were observed by scanning electron microscope (SEM) and atomic force microscopy (AFM) analysis. The surface roughness (Ra) for TiO2/Glass and TiO2/SiO2 was measured ~ 5 and 19 nm, respectively. The hardness of nanolayers on the glass was evaluated and scratch thickness for 1000 g sinker was measured ~150 nm. The self-cleaning properties were tested in dry condition (RH<15%) under UV irradiation by evaluating the oleic acid photodegradation and monitoring the hydrophilic properties of the surface with a contact angle measurement. The result showed that contact angle of the layer decreases from 77 to 42° after 25 h UV irradiation. Fourier-transform infrared spectroscopy- Attenuated total reflectance (FTIR-ATR) showed the elimination of C=O bonds of oleic acid on the surface after UV light irradiation. Water droplet contact angle measurement on TiO2 nano-layer exhibited a less hydrophilicity after UV irradiation and the contact angle changed from 15 to 40°, which may be due to the low atmospheric humidity. Adding SiO2 nanoparticles increases roughness of the nano-layer, from 5 to 19 nm, without a significant effect on the photodegradation rate of oleic acid.
