The inhibition of mild steel corrosion in sulfuric acid environment was evaluated by citrulline and glutamine at fixed temperatures. The tools used for this evaluation were potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and mass loss (ML) measurements. Also, the morphology of mild steel surfaces was examined prior to and after corrosion adding the tested inhibitors by scanning electron microscopy (SEM). The evaluated inhibition efficiencies (% IEs) of the tested inhibitors increased with their concentrations but decreased with increasing sulfuric acid concentration. Results of PDP technique indicated that the examined compounds behaved as mixed inhibitors with cathodic majority. ML studies revealed that % IEs reduced with increasing temperature. The investigational results acquired from all utilized techniques are agreeable with each others which disclosed that the %IEs of citrulline were higher than glutamine under comparable conditions. The acquired great % IEs of the tested inhibitors was understood on the basis of strong adsorption of amino acids on mild steel surface creating a defensive layer and this adsorption was noticed to accord with Langmuir isotherm. Thermodynamic and kinetic parameters were computed and discussed which confirm the physical adsorption mechanism of the examined inhibitors. The kinetics of the corrosion inhibition by such compounds revealed negative first order of corrosion inhibition process demonstrating the acquired great % IEs of the investigated compounds.

The anti-corrosion efficacies of two polymeric molecules, polyvinyl alcohol (PVA) and alginic acid (AA), on the corrosion of SABIC type-X60 carbon steel (CSX60) in 1.0 M HCl solutions were investigated. Chemical and electrochemical techniques, such as weight loss analysis, galvanostatic polarization, potentiodynamic anodic polarization (PDAP), and electrochemical impedance spectroscopy were employed. The results of these experiments revealed that the anti-corrosion activities increased with decreasing temperatures and increasing concentrations of PVA and AA. The surface morphologies of the investigated steel surfaces were analyzed via scanning electron microscopy. The anti-corrosive strengths of the polymeric molecules with respect to the general and pitting corrosion behavior were demonstrated via the formation of adsorbent films that isolated the CSX60 surface from the aggressive acidic solutions. The inhibitor adsorption followed the Langmuir isotherm model. A few thermodynamic activation parameters were also calculated and discussed. PVA and AA were found to retard the pitting corrosion of CSX60 based on the shift of pitting potential to a nobler direction in the PDAP profiles.

Although antibiotics are fundamentally vital for treating human diseases, they became harmful to the ecosystem if they reach to the environment. Due to antibiotics are intensely vulnerable to oxidation, oxidation of antibiotics can be considered as a recognized tool for removal or degradation of antibiotics to save the humans and ecosystem. The existing research illuminates the kinetics of oxidative degradation of sulfafurazole antibiotic (SFZ) using chromium trioxide (CrO3) in both H2SO4 and HClO4 media. The reactions in both acidic media showed a 1: 1.33±0.07 stoichiometry (SFZ: CrO3). The reliance of the rates of oxidation reactions on the reactants’ concentrations illuminated that the reactions were frst order in [CrO3], whereas in [SFZ] and [H+], their orders were fractional-frst and fractional-second, respectively. The rate of oxidation of SFZ in H2SO4 was discovered to be higher than that observed in HClO4. The oxidation rates were not infuenced by the change in ionic strength (I) or dielectric constant (D). Addition of Cr(III) had not remarked efect on the rates. Free radical intervention tests were positive. The activation quantities were calculated then discussed. A conceivable mechanism of oxidation was anticipated. Furthermore, the rate-law expressions were also derived

Via electrochemical approach, the effect of [4-(4-chloro-phenylazo)-3-hydroxy-5-phenylamino-thiophen-2-yl]- phenyl-methanone (TD) as a corrosion inhibitor for the corrosion of carbon steel (CS) in 1.0 M HCl solution has been demonstrated. Electrochemical examination, surface analysis, and theoretical studies (quantum chemistry and molecular dynamic) were used to examine the efficiency of the inhibitor. Both inhibitor concentration and temperature were found to induce inhibitory responses. According to the findings, this compound acts as a mixed-type inhibitor. It also behaves according to the Langmuir and Henry adsorption isotherms. Thermodynamic parameters were calculated and discussed. Polarization data showed that the examined compounds significantly adsorbed on the steel surface, which rises the inhibition efficiency up to 95 % in the presence of 5 × 10−5 M at 25°C. The predicted molecular dynamics (MD) simulation and quantum chemistry results revealed good consistency with the experimental work

Mn(II), Fe(III),Co(II), Ni(II) and Cu(II) complexes of the ligand named (3-Cyano-6-thiophen-2-yl[4,4′]bipyridinyl-2-yloxy)-acetic acid hydrazide (abbreviated as HL) have been synthesized. Structure assignment of such chelates have been performed by means of analytical and spectral tools which joint assured the formulation of the chelates in 1 M: 1 L ratio with non-electrolytic character for all the complexes. Fe(III) complex is 1:3 electrolyte. The spectral IR toll proved the neutral tridentate ligand nature connecting to the metal ions by the azomethine nitrogen, carbonyl and ester oxygen atoms. Octahedral structure has been concluded for all the isolated chelates as deduced from the UV-Vis spectral analysis. The investigated complexes were tested to protect or restrain the corrosion of copper in 1.0 M HCl solution at 298 K using different techniques. The outcomes being acquired illuminated that the synthesized compounds were discovered to be efficient inhibitors and their % IEs were concluded to be dependent on both concentrations and structures. The order of the % IEs of the tested compounds was: HL-Mn > HL-Fe > HL-Co ≥ HL- Ni > HL-Cu > HL. The acquired high % IEs were ascribed to the powerful adsorption of the organic molecules on the surface of copper which was agreed with Langmuir adsorption isotherm. The kinetics of corrosion inhibition by the examined compounds appeared negative-first order process. PDP results indicated that the complex HL-Mn behaves as a mixed-kind inhibitor with slight anodic seniority. The employed techniques used for the complex HL-Mn were in a good consistence with each other.

Pyrazolones are a class of heterocyclic compounds that contain a pyrazole ring fused to a ketone group. Recent scientific research has focused extensively on the potential anti-inflammatory properties of pyrazolone compounds due to their diverse pharmacological effects in alleviating inflammation and reducing fever. This motivated us to focus on the preparation of these derivatives in a simple and eco-friendly manner. A convenient new green methodology was modified for the preparation of 1-phenyl-3,5-pyrazolidinedione by the sonicated MCR of diethyl malonate, phenylhydrazine, and a catalytic amount imidazole as homogenous organic catalyst in water green solvent in a good yield. On the other hand, some of 4-arylidinepyrazolidinedione derivatives are prepared in the same manner via the treatment of a mixture of diethyl malonate, phenylhydrazine, aromatic aldehydes, and a catalytic amount of imidazole in an aqueous medium. Our target synthesized pyrazolidinediones were elucidated via elemental and several spectral analyses. Due to the importance of pyrazolidinediones in the field of treating inflammation and relieving pain, a number of prepared compounds were chosen to test their efficacy as anti-inflammatory agents using carrageenan-induced foot edema in rats and compare the results with indomethacin, the standard drug. We found that the majority of derivatives yield promising results spanning from good to wonderful, so derivatives (15k, 15b, 15h, 15a, and 15j) yield the best results while derivative (15i) yields an average result. As for the derivative (15f), it yields the lowest results compared to the standard drug. This is due to the difference in the structural composition of these derivatives, which increases the likelihood of their use as antiinflammatory derivatives.

The condensation reaction of bis-oxindole with aniline derivatives produced three derivatives of 1,1-(propane-1,3-diyl)bis(3-(substitutedphenylimino)-indoline-2-one). In addition, one spiro-triazole-oxindole derivative was created by 1,3-dipolar cycloaddition of hydrazonoyl chloride on the C¼ N of the latter Schiff base. The spectral analyses of these bis-oxindole/spiro-triazole-oxindole series proved their structure. The four synthesized bis-oxindole/bis-spiro-triazole-oxindoles, denoted 3a, 3b, 3c, and 6, were tested as copper corrosion inhibitors in 1.0 M H2SO4 at 298 K. For all studied organic compounds, weight loss (WL) was used; electrochemical techniques (potentodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS)) were used for the compound with the highest inhibition efficiency (% IE). The current findings revealed that the tested compounds were determined to be effective inhibitors, and their% IEs were discovered to be dependent on their concentrations and structures. At the same concentrations, the WL results revealed that the order of the% IEs of the tested compounds was: 3a 3c 3b 6 (compound 6 was found to have the highest% IE). The examined compounds’ high IEs are attributed to the forceful adsorption of such molecules on the copper surface, which results in the formation of an adhered protecting layer. Such adsorption was discovered to follow the Langmuir adsorption isotherm. The kinetics of corrosion inhibition by the investigated compounds revealed a negative-first order process, supporting the obtained high% IEs. According to PDP results, compound 6 behaves as a mixed inhibitor with a cathodic majority. The collected results for the compound 6 regarding the values of % IEs obtained via the three employed techniques were compared and designated a good concordance between all utilized techniques.

This paper investigates the performances of two synthesized formamidine derivatives, namely: N,N-dimethyl-N’- (pyridin-2-yl) formamidine (A) and N,N-dimethyl-N’-(pyrimidin-2-yl) formamidine (B) to inhibit the corrosion of copper in 1.0 M HNO3 solution at fixed temperatures. Different tools, viz. electrochemical, chemical, and microscopic techniques were utilized in this paper. The evaluated inhibition efficiencies (% IEs) of the tested formamidine derivatives increased with their concentrations. Results indicated that the tested compounds acted as mixed-kind inhibitors with anodic seniority. The acquired great% IEs of such compounds were mainly attributed to the strong adsorption of the compounds’ molecules on the copper surface. The mode of adsorption was agreed with Langmuir isotherm. The results acquired from all utilized tools agreed with each other which disclosed that the %IE values of inhibitor A were somewhat lesser than those of inhibitor B under analogous circumstances. The influence of temperature was investigated and revealed that the %IE values decreased with rising temperature. Also, thermodynamic parameters were evaluated and discussed herein. The kinetics and mechanisms of the copper corrosion and its inhibition by the tested compounds were investigated. Molecular modeling provided strong evidence for the preference of the molecules A and B for their adsorption on the copper surface, while DFT investigations underlined the importance of N heteroatom as a relevant local site for molecular adsorption.

Although many different human activities such as the oil and gas sector, mineral production, utilities, transportation, etc. depend on the utilization of steel and its alloys, they are highly susceptible to corrosion, especially in acidic media. Hence, processing entails substantial material expenditures due to metal losses. In this regard, the inhibitory characteristics of the synthetic heterocyclic derivative (3aR,7S,7aS)-4,5,6,7,8,8-hexachloro-1,3- dioxo-1,3,3a,4,7,7a-hexahydro-2H-4,7-methanoisoindol-2-yl)benzenesulfonamide (MBSI) was studied against corrosion of C-steel in 0.5 M H2SO4 at 25-55 ◦C. The structure of the synthesized molecule was confirmed by FTIR, 1 H-NMR, 13C-NMR, and MS. Weight-loss, potentiodynamic polarization, electrochemical impedance spectroscopy, electrochemical frequency modulation measurements as well as theoretical analyses were employed in this investigation. The results showed that the investigated MBSI compound functions as an efficient inhibitor with a physical adsorption nature on the surface of carbon steel. MBSI concentration causes the inhibition efficiency to rise, reaching a maximum of 94% for the steel alloy corrosion at 37 × 10− 6 M and 25◦C. The synthesized compound was suggested to act as a mixed-type inhibitor. SEM surface analysis showed the construction of a protective layer at the carbon steel surface. DFT-based quantum chemical indices provided more insight into the inhibitory mechanism. Molecular dynamics (MD) simulations were also applied to predict the conformational adsorption change of the inhibitor on the iron surface. In addition, thermodynamic and kinetic parameters were calculated. The experimental results are largely consistent with the theoretical results.

In this report, N-benzylhydrazinecarbothioamide (BHCTA) was investigated as an organic inhibitor for the corrosion of copper substrate in 3.5 wt.% sodium chloride electrolyte at 298 K. The inhibition efficiency of BHCTA was examined using electrochemical, chemical and theoretical tools. The gained outcomes indicated a supreme inhibition efficiency of BHCTA which exceeded 95 % upon addition of 1.00 mM of BHCTA. Such supreme efficiency was discussed on the basis of decisive adsorption of BHCTA molecules on the copper substrate that hinders concurrently the anodic oxidation and cathodic reduction reactions progressions. The adsorption of BHCTA on the copper surface was discovered to obey Langmuir isotherm. The resulting value of Gads0 = −35.7 kJ mol−1 indicates that BHCTA molecules adsorb on the copper surface through a spontaneous mix of physisorption and chemisorption processes. A scanning electron microscope was used to examine the effect of BHCTA adsorption on the morphology of the copper surface. Theoretical calculations showed that BHCTA has good adsorption properties on Cu substrate. There is a good consistency between the applied experimental and theoretical tools, confirming the validity of the gained outcomes.