In this study, we report the design and synthesis of a series of non-porous amorphous polyethyleneimine-based adsorbents, specifically PEI-PD, PEI-TC, and PEI-CC, for selective adsorption of anionic dyes from aqueous solutions. Utilizing pyromellitic dianhydride (PD), terephthaloyl chloride (TC), and cyanuric chloride (CC) as cross-linking agents, we produced adsorbents with distinct morphological and adsorption characteristics. Scanning electron microscopy (SEM) revealed that PEI-PD and PEI-TC exhibit rough, folded surfaces, with total pore volumes of 0.0001 cm³ /g, 0.0002 cm³ /g, respectively, whereas PEI-CC displays particulate features with total pore volumes of 0.0040 cm³ /g, confirming non-porous nature. XRD and SAED analyses confirmed the amorphous state. Zeta potential increased for the PEI based adsorbents, correlating with enhanced electrostatic adsorption. IGMH analysis revealed non-covalent interactions, including hydrogen bonding, also contribute to adsorption. Further adsorption studies indicated pseudo-second-order and Langmuir model fits, suggesting chemisorption and monolayer adsorption. The adsorption performance was evaluated using various dyes, demonstrating that cross linker structure significantly influences adsorption efficiency. PEI-TC demonstrates the highest adsorption capacity for Congo red, reaching 3089.49 mg/g, due to its para-substituted linkage enhancing molecular flexibility, while the adsorption capacity of PEI-CC was 793.85 mg/g, as the meta-substituted CC linkage causes the molecular chains stack closely together and reduces the available free space, leading to a decreased specific surface area. Under simulated real conditions, the removal rate remained above 90 %. This study offers insights into the critical role of building blocks in the development of efficient adsorbents, highlighting the importance of polymer structure on adsorption performance.

中文翻译：

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无孔无定形 PEI 基聚合物的设计与制备及其对阴离子染料的吸附性能


在本研究中，我们报道了一系列无孔无定形聚乙烯亚胺基吸附剂的设计和合成，特别是 PEI-PD、PEI-TC 和 PEI-CC，用于从水溶液中选择性吸附阴离子染料。利用邻苯二甲酸二酐 （PD）、对苯二甲酰氯 （TC） 和三聚氯氰 （CC） 作为交联剂，我们生产了具有独特形态和吸附特性的吸附剂。扫描电子显微镜 （SEM） 显示 PEI-PD 和 PEI-TC 表现出粗糙、折叠的表面，总孔体积分别为 0.0001 cm³ /g、0.0002 cm³ /g，而 PEI-CC 表现出颗粒特征，总孔体积为 0.0040 cm³ /g，证实了无孔性质。XRD 和 SAED 分析证实了非晶态。基于 PEI 的吸附剂的 Zeta 电位增加，与增强的静电吸附相关。IGMH 分析显示，包括氢键在内的非共价相互作用也有助于吸附。进一步的吸附研究表明准二级和 Langmuir 模型拟合，表明化学吸附和单层吸附。使用各种染料评估吸附性能，证明交联剂结构显着影响吸附效率。PEI-TC 对刚果红的吸附能力最高，达到 3089.49 mg/g，因为它的对位取代键增强了分子柔韧性，而 PEI-CC 的吸附能力为 793.85 mg/g，因为间位取代的 CC 键导致分子链紧密堆叠在一起并减少了可用的自由空间，导致比表面积降低。在模拟真实条件下，去除率保持在 90% 以上。 本研究深入了解了构建单元在高效吸附剂开发中的关键作用，强调了聚合物结构对吸附性能的重要性。