Rapid Size Classification of Ultrafine Particles Using Surface Characteristics

Abstract

Size classification of ultrafine particles is one of the most difficult techniques in materials processing. We developed a novel ultrafine particle separation technique based on interfacial properties. In this work, rapid size classification of silica particles (100-300nm) from suspension was examined in various solution chemistry by column bed system packed with fibrous ferro-nickel slag (FS). Smaller particles were selectively attached to the FS, while larger ones had passed through the column bed as an effluent. Classification efficiency depended on pH and ionic strength. Optimum classification was attained at pH3.5 and 10mmol/dm³ KNO₃. These results were explained by DLVO theory, suggesting that surface characteristics of both particle and collector medium virtually determined the separation efficiency. Furthermore, particle concentration and flow velocity had influence on classification efficiency. This method proved to be simple, rapid, and cost-effective for classifying ultrafine particles in aqueous media.