“…Experiments have been carried out in the past decades to determine the factors affecting the agglomeration behavior of PM 2.5 under the acoustic field (Volk et al, 1976;Rajendran et al, 1979;Tiwary et al, 1984;Hoffmann et al, 1993;Kashkoush and Busnaina, 1993;Sharifi et al, 1994;Capéran et al, 1995;Manoucheri and Ezekoye, 1996;Gallego-Juárez et al, 1999;Spengler and Jekel, 2000;De Sarabia et al, 2003;Komarov et al, 2004;Liu et al, 2009;Liu et al, 2011;Wang et al, 2011;Yan et al, 2015). The experimental results indicated that the removal efficiency using acoustic agglomeration depends on the acoustic frequency and intensity, particle size and concentration, and residence time.…”