Abstract In this research, the geometric and electronic structure of the Acid Blue 25 dye as adsorbate and SBA-15 mesoporous silica functionalized with cross-linked polyacrylic acid (CPAA) polymer (SBA-15/CPAA) as adsorbent are studied using density functional theory (DFT) in the aqueous phase. In order to determine the best site of the dye for interacting with adsorbent, the atomic Hirshfeld charges and frontier orbitals are investigated. The result of this investigation confirms that the sulfonate group of the dye is the best nucleophilic site. The adsorbent has two protonated sites (–NH2+ and = OH+) to attract dye anion. The evaluation of calculated adsorption energy, quantum descriptors such as electronic chemical potential (μ) and chemical hardness (η), dipole momentum and solvent effect are shown that the (–NH2+) group in comparison with (=OH+) group attracts the sulfonate group of the dye with more potent force and forms more stable complex. The adsorbent and adsorbate species have the full charge before adsorption. The results of computed transferred charge and the bond order determined that the interaction is mainly electrostatic. In this work, thermodynamic parameters such as enthalpy, entropy, and Gibbs free energy changes are calculated. The results of these parameters showed that the adsorption is an exothermic and spontaneous process. Besides, the obtained values of thermodynamic parameters are in the range of electrostatic interaction.

中文翻译：

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SBA-15包覆的CPAA对酸性蓝25染料在水溶液中的吸附：密度泛函理论研究

摘要 本研究利用密度泛函理论研究了作为吸附质的酸性蓝 25 染料和交联聚丙烯酸 (CPAA) 聚合物 (SBA-15/CPAA) 功能化的 SBA-15 介孔二氧化硅的几何和电子结构。 (DFT) 在水相中。为了确定染料与吸附剂相互作用的最佳位置，研究了原子赫什菲尔德电荷和前沿轨道。这项调查的结果证实染料的磺酸盐基团是最好的亲核位点。吸附剂有两个质子化位点（–NH2+ 和 = OH+）来吸引染料阴离子。计算吸附能、电子化学势 (μ) 和化学硬度 (η) 等量子描述符的评估，偶极动量和溶剂效应表明，与（=OH+）基团相比，（-NH2+）基团以更强的力量吸引染料的磺酸根基团并形成更稳定的络合物。吸附剂和被吸附物质在吸附前已充满电。计算转移电荷和键序的结果确定相互作用主要是静电。在这项工作中，计算了热力学参数，如焓、熵和吉布斯自由能变化。这些参数的结果表明吸附是一个放热和自发过程。此外，获得的热力学参数值在静电相互作用范围内。吸附剂和被吸附物质在吸附前已充满电。计算转移电荷和键序的结果确定相互作用主要是静电。在这项工作中，计算了热力学参数，如焓、熵和吉布斯自由能变化。这些参数的结果表明吸附是一个放热和自发过程。此外，获得的热力学参数值在静电相互作用范围内。吸附剂和被吸附物质在吸附前已充满电。计算转移电荷和键序的结果确定相互作用主要是静电。在这项工作中，计算了热力学参数，如焓、熵和吉布斯自由能变化。这些参数的结果表明吸附是一个放热和自发过程。此外，获得的热力学参数值在静电相互作用范围内。这些参数的结果表明吸附是一个放热和自发过程。此外，获得的热力学参数值在静电相互作用范围内。这些参数的结果表明吸附是一个放热和自发过程。此外，获得的热力学参数值在静电相互作用范围内。