Effect of surfactant concentration on fine particle removal enhanced by atomization agglomeration: an experimental and molecular dynamics simulated study

Atomization agglomeration has emerged as a promising pre-treatment technology for enhancing the removal efficiency of fine particles. The addition of surfactants to the atomizing liquid has demonstrated significant potential in improving the agglomeration effect. Nevertheless, the underlying mechanisms governing the influence of surfactant concentration on this process remain insufficiently understood. To address this, this study systematically investigated the effects and mechanisms of surfactant concentration on fine particle removal through atomization agglomeration, using the commonly employed SDBS surfactant and methylated silica particles. Experimental results revealed that increasing the surfactant concentration, particularly near the critical micelle concentration, significantly improved fine particle removal efficiency. This improvement was attributed to the reduction in surface tension of atomizing liquid, which led to a decrease in the average droplet size, an increase in droplets axial velocity, and improved wettability on particle surfaces, all of which contributed to enhanced atomization agglomeration and more effective fine particle removal. Molecular dynamics simulations further demonstrated that as the number of surfactant molecules increased, the surfactant molecules adopted a more upright arrangement at the gas–liquid interface, reducing interfacial tension and improving droplet fragmentation. Simultaneously, the surfactant molecules exhibited more stable adsorption on solid surfaces, with hydrophilic head groups attracting water molecules through hydrogen bonding, forming a compact hydration layer that improved wettability on the particle surfaces. However, when surfactant concentration became excessive, the molecules began to aggregate at both the gas–liquid and solid–liquid interface. These findings provide valuable insights for the selection and development of surfactants to improve atomization agglomeration and enhance the control of industrial fine particle.