GB1378884A - Electroflotation process - Google Patents

Abstract

1378884 Electroflotation ELECTRICITY COUNCIL 25 Feb 1972 [25 Feb 1971] 5445/71 Heading C1C [Also in Division C7] Finely divided solid particles (including waxes fats and greases), are separated from a liquid in which they are dispersed, e.g. an electrophoretic suspension or oil-in-water emulsion, by electroflotation comprising electrolysing the liquid, e.g. water to form gas bubbles using at least two horizontal electrodes disposed one above the other at the lower end of the vessel containing the liquid, the upper electrode(s) being perforated to allow the passage of bubbles generated at the lower electrode and the anode(s) comprising a coating of Pb-O 2 electro-deposited on to a substrate or Ti. The vessel may be provided with an inlet and outlet on opposite sides for a continuous liquid treating process, separated particles being retained in the vessel on the liquid surface. An anode may be formed by degreasing a Ti substrate, e.g. with trichloroethylene, removing the Ti oxide film therefrom by cathodization, e.g. in H 2 SO 4 , and electrodepositing PbO 2 thereon from a solution containing one or more lead salts so that the anode current density is increased during electrodeposition, e.g. first at 20 to 50 mA./cm.<SP>2</SP>, then at 50 to 100 mA./cm.<SP>2</SP>. The Ti substrate may be grid or gauge. An expanded stainless steel, mild steel or brass cathode may be used. For an electrophoretic suspension, migration of charged particles to a particular electrode may be prevented by shielding with a plurality of electrodes of opposite charge. A flocculating agent may be added to break an emulsion prior to electroflotation.