Effect of plasma-activated water on the settling characteristics of ultrafine kaolinite

Coal slurry water is a complex multiphase system, and its settling characteristics are influenced not only by the solid phase coal slime but also by the liquid phase water. This paper firstly explores the effect of plasma-activated water (PAW) on the settling of ultrafine kaolinite through settling experiments, turbidity tests & dynamic observations. The findings show that PAW significantly improves the settling behavior of ultrafine kaolinite, manifested by an increased settling velocity, higher final settling height, shorter settling end time, and reduced turbidity of the supernatant. Furthermore, the potential mechanisms by which PAW enhances the settling of ultrafine kaolinite are analyzed through laser particle size detections, fractal dimension calculations, zeta potential measurements & contact angle determinations. The mechanism analysis indicates that PAW not only reduces the electrostatic repulsion of ultrafine kaolinite particles but also enhances the hydrophobicity, thereby increasing both the size and density of ultrafine kaolinite flocs, which improves the settling performance of ultrafine kaolinite. This study not only provides new insights for enhancing ultrafine kaolinite settling with PAW but also offers new approaches for the efficient settling of coal slurry water.