Reinforcing steel (RS) is mainly used in building construction and many industries, but it suffers from corrosion problems, especially in acidic environments. Biopolymers are characterized by their unique chemical composition, as they contain a variety of functional groups that are capable of binding strongly to the metal surface and forming a protective layer on it. Herewith, two biopolymers, viz. dextrin (Dex) and inulin (Inu), were tested as eco-friendly inhibitors for the corrosion of RS in 1.0 M HCl medium at different temperatures. Various experimental tools were utilized in this research. The inhibition efficiencies (% IEs) of the tested polymeric compounds were improved by increasing their doses while reducing with rising temperature. The % IEs of Dex and Inu at a dose of 500 mg/L reached 85% and 93%, respectively. The examined biopolymers displayed cathodic/anodic behavior (mixed type) with a foremost anodic one. The acquired higher % IEs were demonstrated by intense adsorption of Dex and Inu on the RS surface fitting the Langmuir isotherm. The influence of rising temperature in the range of 288–318 K on the corrosion behavior was examined, and the evaluated thermodynamic and kinetic parameters sustained the mechanism of physical adsorption of the polymeric inhibitors. Additionally, the kinetics of corrosion, as well as its inhibition by Dex and Inu, were also investigated. The SEM micrographs of the RS surfaces were accorded with all utilized experimental tools. The results gained from all used tools were discovered to be in good agreement with each other.

Herein, the inhibition impacts of chitin, pectin, and amylopectin as carbohydrate polymers on the corrosion of mild steel in 0.5 M HCl were researched utilizing various experimental and theoretical tools. The acquired outcomes showed that the inhibition efficiencies (% IEs) of the tested carbohydrate polymers were increased by raising their concentrations and these biopolymers acting as mixed-kind inhibitors with major anodic ones. The acquired % IEs values were reduced with rising temperature. The higher % IEs of the tested polymers were inferred via powerful adsorption of the polymeric molecules on the steel surface and such adsorption obeyed the Langmuir isotherm. The computed thermodynamic and kinetic quantities confirmed the mechanism of physical adsorption. The kinetics and mechanisms of corrosion and its protection by polymeric compounds were illuminated. The results obtained from all the techniques used confirmed that there was good agreement with each other, and that the % of IEs followed the sequence: chitin > amylopectin > pectin.

This study investigated diferent amino acid-based surfactants (AASs), also known as biosurfactants, including sodium N-dodecyl asparagine (AS), sodium N-dodecyl tryptophan (TS), and sodium N-dodecyl histidine (HS) for their potential anticorrosion, antibacterial, and antidermatophyte properties. The chemical and electrochemical techniques were employed to examine the copper corrosion inhibition efcacy in H2SO4 (1.0 M) solution at 298 K. The results indicated their promising corrosion inhibition efciencies (% IEs), which varied with the biosurfactant structures and concentrations, and the concentrations of corrosive medium. Higher % IEs values were attributed to the surfactant adsorption on the copper surface and the production of a protective flm. The adsorption was in agreement with Langmuir adsorption isotherm. The kinetics and mechanisms of copper corrosion and its inhibition by the examined AASs were illuminated. The surfactants behaved as mixed-kind inhibitors with minor anodic priority. The values of % IEs gained from weight loss technique at a 500 ppm of the tested surfactants were set to be 81, 83 and 88 for AS, HS and TS, respectively. The values of % IEs acquired from all the applied techniques were almost consistent which were increased in the order: TS>HS≥AS, establishing the validity of this study. These surfactants also exhibited strong broad-spectrum activities against pathogenic Gram-negative and Gram-positive bacteria and dermatophytes. HS exhibited the highest antimicrobial activity followed by TS, and AS. The sensitivity of pathogenic bacteria varied against tested AASs. Shigella dysenteriae and Trichophyton mantigrophytes were found to be the most sensitive pathogens. HS exhibited the highest antibacterial activity against Shigella dysenteriae, Bacillus cereus, E. coli, K. pneumoniae, and S. aureus through the formation of clear zones of 70, 50, 40, 39, and 35 mm diameters, respectively. AASs also exhibited strong antifungal activity against all the tested dermatophyte molds and fungi. HS caused the inhibition zones of 62, 57, 56, 48, and 36 mm diameters against Trichophyton mantigrophytes, Trichophyton rubrum, Candida albicans, Trichosporon cataneum, and Cryptococcus neoformans, respectively. AASs minimal lethal concentrations ranged between 16 to 128 µg/ml. HS presented the lowest value (16 µg/ml) against tested pathogens followed by TS (64 µg/ml), and AS (128 µg/ml). Therefore, AASs, especially HS, could serve as an efective alternative antimicrobial agent against food-borne pathogenic bacteria and skin infections-associated dermatophyte fungi.

Carbon steel is generally exposed to corrosion in acidic media, thus three nonionic surfactants based on pyrazolopyrimidine derivatives were designed and examined for the first time as inhibitors for carbon steel corrosion in 1.0 M HCl solution. The structures of the synthesized pyrazolopyrimidine derivatives and the surfactants were identified using FT-IR, 1 H NMR, and 13C NMR. The inhibition efficiencies (%IEs) of the examined surfactants were set to vary with the structures and concentrations of the designed surfactants. The potentiodynamic polarization experiments indicated that the surfactants proceed as mixed-kind inhibitors with chief anodic ones. Mass-loss studies revealed that the %IEs decreased with rising temperature. The obtained great %IEs (around 90% at 500 ppm) of the designed surfactants were interpreted via strong adsorption of the surfactant molecules on the carbon steel surface and construct a protecting film. The adsorption was set to follow the Langmuir adsorption isotherm. The evaluated thermodynamic parameters sustained the physical nature of the adsorption process. The kinetics of corrosion inhibition by these surfactants were negative fractional-first order reactions. The mechanisms of carbon steel corrosion in HCl media and its inhibition by the designed surfactants were suggested. The investigational outcomes acquired from all utilized techniques are agreeable with each other. The designed surfactants were set to have biological activities and useful surface properties, which makes them have the potential ability to treat various diseases and can be employed in a variety of industrial applications.

The effects of two expired antibacterial drugs, amoxicillin (Amo) cefuroxime (Cef), on the corrosion behavior of Sabic iron in 1.0 M HCl solution were examined using weight loss, galvanostatic polarization (GAP), potentiodynamic anodic polarization, and electrochemical impedance spectroscopy techniques. The outcomes showed that the inhibition efficiency increased with increasing concentrations of Amo and Cef and decreased with temperature. The activity of inhibition of these compounds was elucidated by adsorption on Sabic iron surfaces. The adsorption process obeyed the Langmuir isotherm. The activation and adsorption thermodynamic parameters have been determined and clarified. GAP studies indicated that expired Amo and Cef served as mixed inhibitors. The impedance data showed capacitive loop which indicates that charge transfer governs corrosion reactions. Expired Amo and Cef drugs are good pitting inhibitors by positively shifting the pitting potential. There is a complete agreement between the inhibition efficacies obtained from the different measurements

The kinetics of oxidative degradation of two significant triazole antibiotics (A), viz. fluconazole (Flz) and voriconazole (Vcz), was examined using chromium (VI) oxide (CrVI) in sulfuric and perchloric acid environments. The oxidation reactions were followed spectrophotometrically at fixed ionic strength and at different temperatures. In both acidic environments, the oxidative degradations of the two examined antibiotics were acid-catalyzed. The kinetics of the oxidative degradations in both acids were first order concerning to [CrVI] and fractional-first orders with regard to [A] and [H+] during their alteration. The rates of oxidative reactions exhibited insignificant influences upon disparity of ionic strengths and dielectric constants of the reactions’ media. No intervention of free radicals was detected during the degradation reactions. Some activation methods like heat and addition of certain metal cations (Mg2+ & Ca2+) were also investigated. Under analogous experimental circumstances, the degradation rates in perchloric acid environment were slightly higher than those occurred in sulfuric acid one and the degradation rates of Flz were higher than those of Vcz. The believable oxidative degradation mechanism consistent with the kinetic outcomes was proposed. The derived rate-law expression was set to be in a good harmony with the acquired results. The activation and thermodynamic parameters were computed and discussed. This study announce a simple, safe and inexpensive promising procedure involving a double benefit for the environment and human health: degradation of Flz and Vcz drugs and transformation of the extremely toxic and carcinogenic CrVI oxide to a safe CrIII compound.

The inhibitory strength of two amino acids namely, tryptophan (Tryp) and histidine (Hist) on the corrosion of SABIC iron (SABIC Fe) in a 0.5 M HCl solution was examined utilizing mass loss (MS), electrochemical (PDP and EIS) and theoretical studies. Density functional theory (DFT) and Monte Carlo (MC) simulation were inspected for Tryp and Hist inhibitors. All the corrosion parameters and theoretical data obtained from these studies confirm the inhibiting impact of the two amino acids. The efficacy of inhibition augment with augmentation the concentration of two amino acids from 100 to 500 ppm and reducing at elevated temperature. The effectiveness of the inhibition depends on the presence of some active centers that accelerate the adsorption process and the molar mass of the inhibitors. The inhibition efficacy of Tryp is greater than that of Hist reaching 92.09% at a concentration of 500 ppm while in the presence of Hist it is 89.37% using PDP measurements. Inhibition was demonstrated by spontaneous adsorption of Hist and Tryp on the surface of SABIC Fe according to the Langmuir adsorption isotherm. PDP curves clarified that the Tryp and Hist compounds acted as mixed type inhibitors. A variety of thermodynamic and kinetics parameters were computed and explained. SEM images demonstrate that the protective layer constructed on the surface of Se Fe in the presence of both amino acids. The results obtained from DFT are in complete agreement with the experimental work. Tryp and Hist compounds are adsorbed horizontally onto the surface of Fe (110).

Divalent cobalt and copper chelates of the two ligands 1-(1-ethoxycarbonylmethyl-2-o xoindolin-3-ylidene) thiosemicarbazide (EOIT) and 1-(1-benzyl-2-oxoindolin-3-ylidene) thiosemicarbazide (BOIT) are the target compounds of the current study. Identification of the structures and geometries of these compounds have been performed using the possible physicochemical and analytical instruments. Elemental analysis, molar conductance and thermal analysis assured the composition of the four chelates to be [Co(BOIT)Cl]
1.5H2O (BOIT-Co), [Cu(BOIT)Cl] (BOITCu), [Co(EOIT)Cl2(H2O)]
5H2O (EOIT-Co) and [Cu(EOIT)Cl]
Cl (EOIT-Cu) which was further confirmed by the measurement of mass spectra. The architecture arrangement of the ligand atoms around Co and Cu centers has been determined depending on the UV–Vis spectral measurements and calculation of meff values. This proved that the copper compounds were square planer whereas the cobalt complexes were tetrahedral or octahedral arrangements. These compounds were examined as corrosion inhibitors for Sabic iron in 1.0 M HCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy, mass-loss and scanning electron microscopy techniques. The acquired outcomes disclosed that the examined compounds were found to have high inhibition efficiencies (% IEs) which were dependent on their concentrations and composition. The obtained high % IEs (83–87% at concentration of 400 mg/l) were interpreted by strong adsorption of the compounds’ molecules on the iron surface and such adsorption was discovered to follow Langmuir adsorption isotherm. At the same concentration, the % IEs are slightly increased in the order: EOIT-Cu > BOIT-Cu > EOIT-Co > BOIT-Co. Finally, the investigational results obtained from all employed techniques were in a good consistent with each other.

The use of light radiation to cause the dissociation of water into hydrogen (H₂) gas has tremendous promise as a green method of hydrogen production. Herein, we reported a comparative study for the photocatalytic activity of TiO₂ nanocomposite with two co-catalysts e.g., Pt or Cu nanocrystals (3–4 nm) using different synthesis procedures; incipient wet impregnation (Imp), hydrothermal (HT), or photo-deposition (PD) methods. The effect of catalyst mass loading percentages (0.1–1 wt.%) was investigated. The mass loading of 0.3 wt% for both co-catalysts exhibited the highest value of the generated hydrogen. Even without a precious metal such as Pt, Cu/TiO₂ synthesized using the PD method provided an initial rate of 24 mmol h^-1g⁻¹, which is 3.5 and 1.4 times higher than the composite synthesized using HT and Imp methods. On the other hand, the highest rate for Pt co-catalyst was observed for the Imp method with a rate of 58 mmol h^-1g⁻¹ which was higher by 1.6 and 1.1 times than the composite synthesized using PD and HT methods, respectively. This study offers new perspectives on the significant influence of the co-catalyst deposition technique on the efficiency of photocatalysis for producing hydrogen through water splitting.

Copper is primarily used in many industrial processes, but like many other metals, it suffers from corrosion damage. Polymers are not only one of the effective corrosion inhibitors but also are environmentally friendly agents in doing so. Hence, in this paper, the efficacy of two polyelectrolyte polymers, namely poly(acrylic acid) (PAA) and polyacrylamide (PAM), as corrosion inhibitors for copper in molar nitric acid medium was explored. Chemical, electrochemical, and microscopic tools were employed in this investigation. The weight-loss study revealed that the computed inhibition efficiencies (% IEs) of both PAA and PAM increased with their concentrations but diminished with increasing HNO3 concentration and temperature. The results revealed that, at similar concentrations, the values of % IEs of PAM are slightly higher than those recorded for PAA, where these values at 298 K reached 88% and 84% in the presence of a 250 mg/L of PAM and PAA, respectively. The prominent IE% values for the tested polymers are due to their strong adsorption on the Cu surface and follow the Langmuir adsorption isoform. Thermodynamic and kinetic parameters were also calculated and discussed. The kinetics of corrosion inhibition by PAA and PAM showed a negative first-order process. The results showed also that the used polymers played as mixed-kind inhibitors with anodic priority. The mechanisms of copper corrosion in nitric acid medium and its inhibition by the tested polymers were discussed. DFT calculations and molecular dynamic (MD) modelling were used to investigate the effect of PAA and PAM molecular configuration on their anti-corrosion behavior. The results indicated that the experimental and computational study are highly consistent.