This work involves the synthesis of two chitosan derivatives by reacting chitosan, extracted from shrimp shells in eastern Morocco, with 2-nitrobenzaldehyde via a Schiff base reaction. An amino derivative of chitosan was then produced by reducing the imine group created by sodium borohydride. We investigated the molecular weight (Mw), crystallinity index (CrI), and degree of deacetylation (DDA) of the isolated chitosan, among other characteristic features. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR) were used to characterize the extracted chitosan (CS), 2-nitroben-chitosan Schiff derivative (CS-2NI), and chitosan amino derivative (CS-2NA). In a corrosive medium of 1 M HCl, the three ligands, CS, CS-2NI, and CS-2NA, were used as mild steel corrosion inhibitors. Electrochemical studies were used to analyze the surface shape and assess the inhibitory efficiency. They reveal a significant inhibitory efficiency of 92.31% for the CS-2NI derivative, highlighting the effectiveness of the imine group (═N−) and the nitro group (−NO₂) compared to the two amino groups (−NH₂ and −NH−) present in the CS-2NA derivative. To support experimental research, a computational study was carried out that combined the simulated annealing technique. The three inhibitors behave as mixed-type corrosion inhibitors. Thermodynamic analyses and adsorption studies revealed that the tested inhibitors create covalent bonds with the steel surface (chemisorption) as well as physical interactions (physisorption), in accordance with the Langmuir model. The identification of the ligands’ adsorption sites on the steel surface was made more accessible by computational methods, demonstrating the relationship between the inhibitory properties and the chemical structure of these biodegradable and biocompatible biopolymers.

中文翻译：

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取代基对壳聚糖衍生的可持续缓蚀剂的影响：抑制和吸附性能的实验和计算研究


这项工作涉及通过席夫碱反应将从摩洛哥东部虾壳中提取的壳聚糖与 2-硝基苯甲醛反应来合成两种壳聚糖衍生物。然后通过还原硼氢化钠产生的亚胺基团来生成壳聚糖的氨基衍生物。我们研究了分离壳聚糖的分子量 （Mw） 、结晶度指数 （CrI） 和脱乙酰化程度 （DDA） 以及其他特征。采用热重分析 （TGA） 、X 射线衍射 （XRD） 和衰减全反射傅里叶变换红外光谱 （FTIR-ATR） 对提取的壳聚糖 （CS） 、 2-硝基苯-壳聚糖 希夫衍生物 （CS-2NI） 和壳聚糖氨基衍生物 （CS-2NA） 进行表征。在 1 M HCl 的腐蚀性介质中，使用 CS、CS-2NI 和 CS-2NA 三种配体作为低碳钢缓蚀剂。电化学研究用于分析表面形状并评估抑制效率。他们揭示了 CS-2NI 衍生物的显着抑制效率为 92.31%，突出了与 CS-2NA 衍生物中存在的两个氨基（−NH₂ 和 −NH −）相比，亚胺基 （═N−） 和硝基 （−NO₂） 的有效性。为了支持实验研究，进行了一项结合了模拟退火技术的计算研究。这三种缓蚀剂的作用类似于混合型缓蚀剂。热力学分析和吸附研究表明，根据 Langmuir 模型，测试的抑制剂与钢表面产生共价键（化学吸附）以及物理相互作用（物理吸附）。 通过计算方法，可以更轻松地识别配体在钢表面上的吸附位点，证明了这些可生物降解和生物相容性生物聚合物的抑制特性与化学结构之间的关系。