Collision kinetics and electrostatic dispersion of airborne submicrometer fractal agglomerates

Collision and electrostatic dispersion rates of airborne submicrometer TiO2 agglomerates were measured and compared with the classical collision theor y for spheres as well as with models accounting for the agglomerate structu re in terms of the fractal dimension and electrostatic effects such as Coul omb and van der Waals interactions. According to the authors' knowledge, th is is the first time that the agglomerate fractal dimension and electrostat ic effects have been considered simultaneously in determining the collision frequency function of agglomerates. The observed enhancement in the collis ion frequency of agglomerates was found mainly to be a result of electrosta tic particle interactions. Nonspherical particle shape has only a comparati vely small influence on the collision probability, on the order of 10-20%. Electrostatic dispersion coefficients of agglomerates were found to be simi lar to those of spheres. (C) 2001 Academic Press.