Engineering Department, College of Engineering and Computer Science, German University of Technology in Oman, Oman.
Faculty of Engineering, Warith Al-Anbiyaa University, Karbala, 56001, Iraq.
J Mol Graph Model. 2024 Jul;130:108774. doi: 10.1016/j.jmgm.2024.108774. Epub 2024 Apr 16.
Water is an indispensable material for human life. Unfortunately, the development of industrial activities has reduced the quality of water resources in the world. Meantime, heavy metals are an important factor in water pollution due to their toxicity. This study highlights the method for the capture of heavy metal ions from wastewater using the procedure of adsorption. The adsorption of toxic heavy metal ions (Pb, Hg, and Cd) on CaC as well as CrC carbide-nitride MXene monolayers is investigated using the density functional theory. We have carried out the optimization of the considered MXenes by nine DFT functionals: PBE, TPSS, BP86, B3LYP, TPSSh, PBE0, CAM-B3LYP, M11, and LC-WPBE. Our results have shown a good agreement with previously measured electronic properties of the CaC and CrC MXene layers and the PBE DFT method. The calculated cohesive energy for the CaC and CrC MXene monolayers are -4.12 eV and -4.20 eV, respectively, which are in agreement with the previous studies. The results reveal that the adsorbed heavy metal ions have a substantial effect on the electronic properties of the considered MXene monolayers. Besides, our calculations show that the metal/MXene structures with higher electron transport rates display higher binding energy as well as charge transfers between the metal and CaC and CrC layers. Time-dependent density functional analysis also displayed "ligand to metal charge transfer" excitations for the metal/MXene systems. The larger Ebin for the Pb@CaC as well as Pb@CrC are according to larger redshifts which are expected (Δλ = 45 nm and 71 nm, respectively). Our results might be helpful for future research toward the application of carbide-nitride MXene materials for removing wastewater pollutants.
水是人类生活不可或缺的物质。不幸的是，工业活动的发展降低了世界水资源的质量。同时，重金属由于其毒性是水污染的一个重要因素。本研究强调了利用吸附法从废水中捕获重金属离子的方法。使用密度泛函理论研究了有毒重金属离子（Pb、Hg 和 Cd）在 CaC 以及 CrC 碳氮化物 MXene 单层上的吸附。我们使用九种 DFT 泛函（PBE、TPSS、BP86、B3LYP、TPSSh、PBE0、CAM-B3LYP、M11 和 LC-WPBE）对考虑的 MXenes 进行了优化。我们的结果与 CaC 和 CrC MXene 层的先前测量的电子性质以及 PBE DFT 方法具有良好的一致性。CaC 和 CrC MXene 单层的计算内聚能分别为-4.12 eV 和-4.20 eV，与之前的研究结果一致。结果表明，吸附的重金属离子对所考虑的 MXene 单层的电子性质有重大影响。此外，我们的计算表明，具有更高电子传输速率的金属/MXene 结构具有更高的结合能以及金属与 CaC 和 CrC 层之间的电荷转移。时变密度泛函分析还显示了金属/MXene 体系的“配体到金属电荷转移”激发。Pb@CaC 和 Pb@CrC 的较大 Ebin 对应于较大的红移，这是预期的（分别为 45 nm 和 71 nm）。我们的结果可能有助于未来研究碳氮化物 MXene 材料在去除废水中污染物方面的应用。
