Effect of SiO2-H2O nanofluids on wettability of pulverized coal and the modification mechanism

Abstract

To address the challenge induced by the hydrophobicity of coal dust, it is crucial to explore the impact of innovative wetting agents on the wettability of coal dust. In this regard, the present study focuses on SiO2-H2O nanofluids at four concentrations and pulverized coal with different particle sizes collected from different coal mines. The investigation focuses on the influence of SiO2-H2O nanofluids on the wettability of pulverized coal through an array of tests, encompassing surface tension assessments, viscosity measurements, contact angle analyses, reverse imbibition examinations, shooting of nanoparticle deposition patterns, and scanning electron microscopy. Furthermore, the underlying mechanism by which SiO2-H2O nanofluids enhance the wettability of pulverized coal was analyzed. The findings of the research reveal a substantial enhancement in the wettability of pulverized coal when modified with SiO2-H2O nanofluids. Specifically, when treated with nanofluids at a concentration of 1.5 wt%, the wettability improved by up to 44.61%, while the water absorption rate (WAR) increased by up to 4.82%. Notably, high-concentration nanofluids demonstrated effective suppression of coal dust with larger particle sizes, whereas low-concentration nanofluids addressed smaller particle sizes. SiO2 nanoparticles with high surface energy and robust adsorption characteristics, adhered to and agglomerated on the surface of pulverized coal, forming either globular or chained aggregates. This phenomenon emerged as the main cause for enhancing the wettability of pulverized coal. Finally, the study introduced a concept for an integrated technology aimed at controlling dust in mines, encompassing the preparation, transportation, and spraying of nanofluids. This research holds substantial theoretical and practical importance for the effective management of dust in coal mines.