Separation and enrichment of micro and nano sized particles from aqueous solutions by flotation using colloidal gas aphrons

Abstract

The aim of this work was to investigate the separation and enrichment of micro and nano sized particles by batch and column flotation using colloidal gas aphrons (CGAs). The CGAs were produced using anionic sodium dodecylbenzenesulfonate (SDBS) and cationic hexadecyltrimethylammonium bromide (HTAB) surfactants. The physical properties of the surfactant solutions, formation of CGAs, liquid drainage from the foam as well as liquid rise and bubble size of CGAs were measured. In the batch process, carbon particles showed that the CGAs produced with HTAB enhanced the performance of separation ratio 1.45 and enrichment ratio 1.14. The % removal of carbon was found to be 77% for 100 μm particles while it was 82% using 45 μm particles. By using SDBS, 91% removal was achieved for 400 mg/L concentrated iron particles having size 500 nm. In the column flotation, the % removal of carbon particles was 54% while it was 42% for iron particles. Thus, CGAs generated from anionic SDBS and cationic HTAB surfactants were proved to be effective in separating micro and nano sized particles based on electrostatic interactions.