Wettability effect of ethoxylated nonyl phenol with different ethylene oxide chain length on Shendong long-flame coal surface. (March 2021) - Li, Lin
Graphical abstract: Highlights: The interfaces interaction between NPEO and low rank coal is explored. Experiments are combined with molecular dynamics simulation to exploring the surface modification of coal. Surface energy and adhesion work of coal are calculated. Abstract: Low-rank coal is coal with a low degree of metamorphism, it has high moisture content and strong hydrophilicity. It is important for low rank coal to improve its hydrophobicity. In this paper, the wettability effects of ethoxylated nonylphenol (NPEO) with different ethylene oxide chain length on Shendong long-flame coal surface were explored. Contact angle experiments proved that long-flame coal adsorbing NPEO significantly enhances its surface hydrophobicity, and it is the most effective when the equilibrium concentration is close to its critical micelle concentration. Moreover, NPEO-8 is the best for improving the hydrophobicity of long-flame coal. Compared with long-flame coal without NPEO, the surface energy and adhesion work of coal are lower after adsorbing NPEO, in addition, NPEO-8 is the most effective of three NPEO with 8, 10 and 12 ethylene oxide. NPEO aggregate at the coal/water interface and the hydrophobic carbon chains intertwine to form a hemispherical aggregate structure, which reduce the interaction energy between water and coal. Therefore, the hydrophobicity of long-flame coal was improved after adsorbing NPEO, and NPEO-8 is the best, followed by NPEO-10, NPEO-12 is the last.