College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China.
Int J Mol Sci. 2018 Feb 1;19(2):437. doi: 10.3390/ijms19020437.
Experimental and computational simulation methods are used to investigate the adsorption behavior of the surfactant nonylphenol ethoxylate (NPEO10), which contains 10 ethylene oxide groups, on the lignite surface. The adsorption of NPEO10 on lignite follow a Langmuir-type isotherm. The thermodynamic parameters of the adsorption process show that the whole process is spontaneous. X-ray photoelectron spectroscopic (XPS) analysis indicates that a significant fraction of the oxygen-containing functional groups on the lignitic surface were covered by NPEO10. Molecular dynamics (MD) simulations show that the NPEO10 molecules were found to adsorb at the water-coal interface. Moreover, polar interactions are the main effect in the adsorption process. The density distributions of coal, NPEO10, and water molecules along the Z axis show that the remaining hydrophobic portions of the surfactant extend into the solution, creating a more hydrophobic coal surface that repels water molecules. The negative interaction energy calculated from the density profiles of the head and tail groups along the three spatial directions between the surfactant and the lignitic surface suggest that the adsorption process is spontaneous. The self-diffusion coefficients show that the presence of NPEO10 causes higher water mobility by improving the hydrophobicity of lignite.
采用实验和计算模拟方法研究了含有 10 个环氧乙烷基团的表面活性剂壬基酚聚氧乙烯醚（NPEO10）在褐煤表面的吸附行为。NPEO10 在褐煤上的吸附遵循 Langmuir 型等温线。吸附过程的热力学参数表明整个过程是自发的。X 射线光电子能谱（XPS）分析表明，褐煤表面的含氧官能团中有很大一部分被 NPEO10 覆盖。分子动力学（MD）模拟表明，NPEO10 分子被发现在水煤界面吸附。此外，极性相互作用是吸附过程的主要影响因素。沿 Z 轴的煤、NPEO10 和水分子的密度分布表明，表面活性剂的剩余疏水区分延伸到溶液中，形成更疏水的煤表面，排斥水分子。从表面活性剂与褐煤之间三个空间方向上的头基和尾基密度分布计算得到的负相互作用能表明吸附过程是自发的。自扩散系数表明，NPEO10 的存在通过提高褐煤的疏水性，使水的流动性更高。
