School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
J Hazard Mater. 2021 Feb 5;403:123810. doi: 10.1016/j.jhazmat.2020.123810. Epub 2020 Sep 2.
Two clay minerals, kaolinite (Kaol) and montmorillonite (Mt) with different crystal structures were chosen to investigate the comparative adsorption of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) through batch control experiments and theoretical studies. The systematical isotherm and kinetic studies agreed with Langmuir model and pseudo-second-order model, confirming a monolayer and chemisorption interaction process, respectively. The maximum removal capacities of Kaol and Mt for PBTC were 72.297 mg/g and 121.163 mg/g at pH=3.0 and T=298 K, respectively. Furthermore, the adsorption mechanisms were investigated by molecular dynamic (MD) simulations and density functional theory (DFT). The Interface force field (IFF) was firstly introduced into Materials Studio package to explore the microscopic mechanism of clay mineral interface. The dynamics behaviors verified that the oxygen (O) atom of carboxyl group has stronger affinity at the external surface of Mt, which consistent with the experimental data well. For DFT calculations, quantitative analysis around molecular van der Waals (vdW) surface was adopted to predict reactive sites for the electrophilic reaction. Independent Gradient Model (IGM) and Hirshfeld surface analyses in Multiwfn indicated that the high adsorption effect mainly attributes to hydrogen bond action. These findings improve our ability to explore the related properties occurring at the interface of different clay minerals.
两种不同晶体结构的粘土矿物高岭石（Kaol）和蒙脱石（Mt）被选择用于通过批处理控制实验和理论研究来比较 2-膦酸丁烷-1,2,4-三羧酸（PBTC）的吸附。系统的等温线和动力学研究分别符合朗缪尔模型和准二级模型，证实了单层和化学吸附相互作用过程。在 pH=3.0 和 T=298 K 时，Kaol 和 Mt 对 PBTC 的最大去除容量分别为 72.297 mg/g 和 121.163 mg/g。此外，通过分子动力学（MD）模拟和密度泛函理论（DFT）研究了吸附机制。首次将界面力场（IFF）引入 Materials Studio 软件包中，以探索粘土矿物界面的微观机制。动力学行为验证了羧基的氧（O）原子在 Mt 的外表面具有更强的亲和力，这与实验数据非常吻合。对于 DFT 计算，采用围绕分子范德华（vdW）表面的定量分析来预测亲电反应的反应活性位点。Multiwfn 中的独立梯度模型（IGM）和 Hirshfeld 表面分析表明，高吸附效果主要归因于氢键作用。这些发现提高了我们在不同粘土矿物界面探索相关性质的能力。
