The electrokinetic properties of colloidal magnetic iron oxides.
IM Metcalfe, TW Healy
Langmuir | American Chemical Society (ACS) | Published : 2012
A novel electrokinetic streaming potential technique has been used to determine the ζ potential behavior of three magnetic iron oxides, (Fe(3)O(4), γ-Fe(2)O(3), and CoFe(2)O(4)) as a function of pH and salt concentration. These colloidal materials, (nanosize in one dimension), are held in the form of a plug by means of external magnets. The streaming potential (E) is measured as a function of fluid flow induced by a pressure drop (ΔP) across the plug. The magnetically held plug is found to obey the requirements of the streaming potential technique; in each case an iso-electric point, (iep) independent of salt concentration is observed. However, if one uses the appropriate quantities in the s..View full abstract