Biogenic silica from Equisetum arvense was dispersed in aqueous media by using ball milling, high-energy planetary ball milling and ultrasonication. Zeta potential (zeta), dynamic light scattering, and transmission electron microscopy revealed the electrostatic charge and morphological characteristics of the particles, which formed stable colloidal dispersions. Ball milling and ultrasonication yielded particles of 10 nm in size that clustered into larger structures. Extended milling time was effective in reducing the particle size by ball milling and ultrasonication but not by high-energy planetary ball milling. The colloidal stability of the dispersions was maximized under alkaline conditions (zeta > -30 mV and smallest cluster size of 100-200 nm). (C) 2016 Elsevier B.V. All rights reserved.