Abstract In the present study, the molecular dynamics simulation method was used to investigate the influence on the adsorption capacity of single-walled carbon nanotubes (SWCNTs) to phenol caused by NaCl and an external electrostatic field in saline by calculating the structural parameters, the hydrogen bonding, the interaction energy and the viscosity of the solution system. The results show that when the numbers of added NaCl molecules are ten, twenty and thirty, the coordination number of phenol around the SWCNTs decreases from 150 to 144, 143 and 141, the coordination number of water around phenol increases from 2.133 to 2.257, 2.301 and 3.345, the lifetime of hydrogen bonds between phenol and water increases from 7.02 ps to 7.09 ps, 7.16 ps and 7.22 ps, the interaction energy of SWCNT and phenol decreases from −1571 kJ·mol−1 to −1374.05 kJ·mol−1, −1341 kJ·mol−1 and −1326 kJ·mol−1, and the viscosity of solution increases from 0.70 mPa·s to 0.73 mPa·s, 0.74 mPa·s and 0.76 mPa·s, respectively. These results indicate that the presence of NaCl can decrease the number of phenol molecules around SWCNTs, enhance the hydration of phenol, reduce the phenol's hydrophobic performance, and decrease the interaction between the phenol molecules and the viscosity of the phenol solution, which indicates that the added NaCl can weaken the adsorption capacity of SWCNTs to phenol. Furthermore, when an electrostatic field is applied in saline (with twenty NaCl molecules), the number of salt ions around the SWCNTs decreases, leading to an increase in the adsorption sites for phenol on the surface of the SWCNTs. The electrostatic field can also decrease the interaction energy between water and phenol (from −4662 kJ·mol−1 to −4490 kJ·mol−1) and increase the interaction energy between SWCNT and phenol (from −1361 kJ·mol−1 to −1552 kJ·mol−1); thus, the adsorption between phenol and SWCNT can be enhanced. However, the presence of NaCl suppresses this enhancement caused by the electrostatic field.

中文翻译：

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NaCl和盐水中静电场对苯酚对单壁碳纳米管吸附的影响

摘要 本研究采用分子动力学模拟方法，通过计算结构参数、氢原子浓度，研究了氯化钠和盐水中的外部静电场对单壁碳纳米管（SWCNTs）对苯酚吸附能力的影响。键、相互作用能和溶液系统的粘度。结果表明，当加入的NaCl分子数为10、20和30时，单壁碳纳米管周围苯酚的配位数从150减少到144、143和141，苯酚周围水的配位数从2.133增加到2.257、2.301和 3.345，苯酚和水之间的氢键寿命从 7.02 ps 增加到 7.09 ps、7.16 ps 和 7.22 ps，SWCNT 和苯酚的相互作用能从 -1571 kJ·mol-1 降低到 -1374。05 kJ·mol-1、-1341 kJ·mol-1和-1326 kJ·mol-1，溶液粘度从0.70 mPa·s增加到0.73 mPa·s、0.74 mPa·s和0.76 mPa·s，分别。这些结果表明 NaCl 的存在可以减少 SWCNTs 周围苯酚分子的数量，增强苯酚的水化作用，降低苯酚的疏水性能，降低苯酚分子之间的相互作用和苯酚溶液的粘度，这表明添加NaCl会减弱SWCNTs对苯酚的吸附能力。此外，当在盐水（含有 20 个 NaCl 分子）中施加静电场时，SWCNTs 周围的盐离子数量减少，导致 SWCNTs 表面对苯酚的吸附位点增加。静电场还可以降低水和苯酚之间的相互作用能（从-4662 kJ·mol-1 到-4490 kJ·mol-1），增加单壁碳纳米管和苯酚之间的相互作用能（从-1361 kJ·mol-1 到−1552 kJ·mol−1); 因此，可以增强苯酚和单壁碳纳米管之间的吸附。然而，NaCl 的存在抑制了由静电场引起的这种增强。