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    A critical view of computational chemistry methods in understanding corrosion inhibition of 6-chloro-2- phenylimidazo[1,2-b]pyridazine in 1 M and 5 M HCl
    (Vserossiiskaya Assotsiatsiya Korrozionistov, 2023) Achnine, N.; Driouch, M.; Elhaloui, A.; Lakbaibi, Z.; El Assiri, El H.; Kadiri, M.; Sfaira, M.
    The aim of this article is to highlight some of the pitfalls frequently encountered in the literature. Firstly, deductions based on correlations obtained for a few isolated inhibitors. Secondly, the inability of quantum methods to account for the aggressiveness of the environment. Thirdly, distrust in the interpretation of small differences between energy descriptors in terms of correlation between experimental results and quantum calculations. Finally, the use of overly simplistic surface models. This study highlights the limitations of local reactivity descriptors such as EPF and NPF calculated according to NBO and not according to NPA for the isolated molecule 6-chloro-2-phenylimidazo[1,2-b]pyridazine in both its neutral CP-IPZ and protonated CP-IPZH forms. Also, the calculation of NEBD according to QTAIM, then the calculation of GEDT at the level of the transition states of the iron-CP-IPZH complex. The resulting descriptors take no account of the nature or concentration of the corrosive medium (1 M and 5 M HCl). In addition, DM and MC were used to take account of the concentration of the corrosive solution, inhibitor-metal interactions and the dynamic aspect of the adsorption process. It was shown that despite the difference in adsorption energy of CP-IPZH, which follows the trend in terms of the aggressiveness of the medium, does not reflect the low polarization resistance in 5 M HCl, i.e. ten times lower than that in 1 M HCl.
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    Impact of carbon chain length on the adsorption kinetics of bis-mercapto-benzimidazole MB-Cn-MB (n = 2, 4, 6, 8, 10) at the Q235-steel/1 M HCl interface
    (Vserossiiskaya Assotsiatsiya Korrozionistov, 2023) Achnine, N.; Driouch, M.; Niouri, W.; Kadiri, M.; El Assiri, E. H.; Mousaif, A.; Haoudi, A.
    In the present work, we undertook a study on the effect of increasing the carbon chain from two to ten atoms on bolaform surfactants whose head was a mercapto-benzimidazole {MB-C-n-MB with n = 2, 4, 6, 8 & 10}. A comparative study of the inhibiting effect of MB-C2-MB and MB-C-8-MB at different concentrations was carried out by comparing three techniques, direct (gravimetric) and indirect (stationary {potentiodynamic polarization, PDP} and transient {electrochemical impedance spectroscopy, EIS}). The polarization curves were analyzed qualitatively by visual inspection and then quantitatively by fitting their data using three methods {Tafel-Fit, Stern-Fit or Wagner and Traud-Fit, and Rp-Fit} while those from the transient method were examined both by graphical inspection of Nyquist, Bode and Betova representations, then modeled and fitted using an appropriate equivalent electrical circuit, EEC. To overcome some ambiguities inherent to basic approximations of Tafel's method, discussed in this paper, the cathodic and anodic polarization curves were recorded separately with a potential sweep from low to high overvoltage, then adjusted using the Stern and Jena-Bonhoeffer model. Indeed, examination of the results showed that the approximations inherent in the Tafel treatment and the fitting procedure undertaken led to an overestimation of i(corr) value compared with its value estimated using the Stern model at each concentration of MB-C-2-MB and MB-C-8-MB. Also, we have exhaustively examined the ambiguities, little discussed in the contemporary literature, associated with the modeling, quantitative, and qualitative interpretation of impedance data containing more than one indistinguishable time constant. The inhibiting efficiencies derived from different techniques and methods undertaken showed that MB-C-8-MB was more effective than MB-C-2-MB. To develop an insight into the inhibition mechanism of MB-C-8-MB, six adsorption isotherms, commonly used in the literature, were adapted to the experimental data and critically discussed. The Langmuir model was discarded despite the good statistical parameters of fit, because it remains a hypothetical model that can in no way reproduce the reality of the studied interface. Finally, the polarization resistance values obtained from EIS results for the optimum concentration of 10(-3) M of the different surfactants studied showed that the inhibition efficiencies followed the trend {eta.%(MB-C-2-MB)= 84% < eta%(MB-C-4-MB) < eta%(MB-C-6-MB) < eta%(MB-C-8-MB) approximate to eta%(MB-C-10-MB)=96%}.
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    Tyrosine as a novel potential stabilizer in an electroless Ni-P bath exempt of trisodium citrate as complexing agent: Chemical baths optimization and comparative study
    (Elsevier, 2022) Driouch, M.; Haloui, El; El Assiri, El H.; Achnine, N.; Sfaira, M.; Touhami, M. Ebn; Kaya, S.
    The effect of tyrosine (C9H11NO3) as a new stabilizing agent on the composition and conditions of the electroless plating bath of the Ni-P alloy was studied. A comparative study with trisodium citrate, which is commonly used, as a stabilizing complexing agent revealed the effect of tyrosine in this study. Scanning electron microscopy (SEM) and X-Ray Energy Dispersion (EDX) are used to study the properties of the Ni-P coating deposit developed in the presence of tyrosine and trisodium citrate. The result of this optimization showed that the use of tyrosine causes the concentration of NiSO4 and CH3COONH4 in the bath to decrease to 67% and 85%, respectively. In contrast, the use of trisodium citrate had no effect neither on the composition nor on the effect of the bath conditions of the deposit. In addition, the use of C9H11NO3 as a stabilizing agent in the bath promotes the increase of the phosphorus content more than trisodium citrate when optimizing the accelerating agent in the bath and therefore changes the structure of the Ni-P deposits developed.