Promoting the removal of fine particles by surfactants in a novel cyclone with heterogeneous-condensation agglomeration : a combined experimental and molecular dynamics study

Using heterogeneous-condensation agglomeration to enhance removal of fine particles by conventional equipment is an economical and efficient method. Recently proposed Cloud-Air-Purifying (CAP) technology, which combines heterogeneous-condensation agglomeration with a centrifugal field, has significantly improved the removal efficiency of fine particles in gas cyclones. In this work, surfactants were used to further enhance the removal of fine particles. The effect of three surfactants on promoting the removal of fine particles was investigated experimentally. The results indicated that non-ionic surfactant octylphenol polyoxyethylene ether (10) (OP-10) had the best effect on promoting the removal of methylated silica (SiO2-CH3) particles, because it improved heterogeneous condensation of fine particles and collision agglomeration between particles by improving the surface wettability, resulting in the formation of larger aggregates. Furthermore, the interaction energy, mean square displacement and hydrogen bond interactions in different simulation systems were calculated by molecular dynamics simulation to study the mechanism of surfactants on improving the surface wettability. The simulation results demonstrated the hydrophobic tail chains of OP-10 molecules spontaneously adsorbed on the nonpolar SiO2(0 0 1)–CH3 surface through the Van der Waals interaction, which changed the surface polarity and reduced the solid–liquid interaction energy. Meanwhile, hydrogen bonds were formed between polar head groups and water molecules, which enhanced the interaction between water molecules and the surface. Moreover, the mobility of water molecules is enhanced by surfactant molecules. The spatial distribution of the head group and tail chain of surfactant is an important factor affecting the surface wettability. This work is of great importance for enhancing the removal of fine particles in the dedusting system with heterogeneous-condensation agglomeration technology.