This paper presents a comprehensive study on the corrosion inhibition properties of new organic compounds, (1H-benzimidazol-2-yl)methanethiol (LF₁) and 1-dodecyl-2-((dodecylthio)methyl)-1H-benzimidazole (LF₂), have been examined for inhibiting of Carbon-Steel (C.S) in 1.0 M HCl. Numerous methods, such as potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis, atomic force microscopy (AFM), contact angle measurements, UV-visible spectroscopy, and theoretical calculations, were used to evaluate the effectiveness in preventing corrosion. The two benzimidazoles (LF₁ and LF₂)' inhibitory efficacy rose as their concentration increased, peaking at 88.2% and 95.4% respectively. The polarization graphs show a mixed behavior, with anodic predominance for LF₁ and cathodic predominance for LF₂. Thermodynamic investigations showed that the values of ΔG_ads were −40.0 kJ mol⁻¹ for LF₁ and −43.1 kJ mol⁻¹ for LF₂, highlighting their strong adsorption onto the metal surface. Their adsorption process was in line with the Langmuir isotherm. Density Functional Theory (DFT) and Molecular Dynamics (MD) modeling have been utilized to examine and clarify the relationship between the inhibitor and carbon steel (C.S).

In this study, cellulose nanocrystals (CNCs) were produced from pea peels by acid hydrolysis to be used with pectin and acrylic acid (AAc) to form Pectin-PAAc/CNC nanocomposite by γ-irradiation. The structure, morphology, and properties of the nanocomposite were investigated using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) techniques. The nanocomposite hydrogel was used for the removal of methylene blue dye (MB) from wastewater. The results revealed that the presence of CNCs in the polymeric matrix enhances the swelling and adsorption properties of Pectin-PAAc/CNC. The optimum adsorbate concentration is 70 mg/L. The kinetic experimental data were fit by pseudo-first-order (PFO), pseudo-second-order (PSO), and Avrami (Avr) kinetic models. It was found that the kinetic models fit the adsorption of MB well where the correlation coefficients of all kinetic models are higher than 0.97. The Avr kinetic model has the lowest ∆q_e (normalized standard deviation) value, making it the most suitable one for describing the adsorption kinetics. The adsorption isotherm of MB by Pectin-PAAc follows the Brouers–Sotolongo model while that by Pectin-PAAc/CNC follows the Langmuir isotherm model. The negative values of ∆G confirmed the spontaneous nature of adsorption, and the positive value of ∆H indicated the endothermic nature of the adsorption.

Novel mono, di and tetra cationic surfactant (CS) molecules were synthesized by quaternization reaction of diamide with cetyl-2-chloroacetate with different ratio 1:1, 1:2 and 1:4. The chemical structures of the synthetic compounds were proven by FTIR and ¹HNMR. The synthetic cationic surfactants were examined as corrosion inhibitors for carbon steel (CSt) in 1.0 M HCl solutions using chemical and electrochemical measurements. Some surface-active properties were determined and linked to the inhibition process. The inhibition efficiency increases with increasing concentration of CS molecules and decreasing temperature. Potentiodynamic polarization technique showed that the three CS molecules are classified as mixed inhibitors. The inhibition process was explained by its spontaneous adsorption on the surface of CSt, according to Langmuir isotherm. The results confirmed that the cationic surfactants successfully inhibited the corrosion of CSt in the investigated corrosion medium and the inhibition efficiency reached 96.08%. GRAPHICAL ABSTRACT

1. Carbon steel is of great importance in the industry, as it enters many vital industries that support the national economy, including buildings, bridges, boilers, petroleum industries, and other ...

The inhibitory performance of two polymeric compounds, polythiophene (PT) and polypyrrole (PPy), on the corrosion behavior of mild steel (MSt) in 1.0 M H₂SO₄ solution was systematically investigated using potentiodynamic polarization, potentiodynamic anodic polarization, electrochemical impedance spectroscopy (EIS), and weight loss measurements. The novelty of this study lies in its integrated approach, which correlates experimental chemical and electrochemical analyses with quantum chemical calculations and Monte Carlo simulations to provide a comprehensive understanding of the inhibition mechanism. The results demonstrate that both PT and PPy act as mixed-type inhibitors, significantly reducing corrosion through adsorption onto the MSt surface in accordance with the Langmuir adsorption isotherm. The inhibition efficiency increases with increasing inhibitor concentration, while it decreases with rising temperature, suggesting that the adsorption process is predominantly physical in nature. Polarization measurements further confirm that PT and PPy behave as mixed-type inhibitors and exhibit pitting inhibition behavior, as evidenced by the positive (noble) shift in the pitting corrosion potential with increasing inhibitor concentration. Thermodynamic parameters associated with activation and adsorption processes were determined and discussed in detail. In addition, a comparative study of PT and PPy adsorption on the Fe (110) surface was conducted using quantum chemical descriptors and Monte Carlo simulations. The combined electronic structure analysis and adsorption results consistently indicate that PPy forms a more stable and protective adsorbed layer, in excellent agreement with experimental findings, thereby identifying it as the more effective polymeric inhibitor for mild steel corrosion protection.