Abstract
The efficiency of Cd2+ foam separation with sodium lauryl sulfate and sodium laurate from sodium sulfate and sodium nitrate solution was tested. Foam fractionation of Cd2+ with lauryl sulfate in the form of a hydrated ion pair 2C12H25SO4, Cd2+ is ineffective because of a low recovery and high hydration of the foam. But ion flotation of Cd2+ as a low-solubility salt (C12H25COO)2Cd is highly effective. The presence of electrolyte in the solution has a negative influence on Cd2+ foam fractionation with lauryl sulfate because of an increase of inert salt concentration which causes competition for the collector between colligend Cd2+ and the added Na+ ions, and because of simultaneous increase in the thickness of water sheaths around the gas bubbles. In the case of ion flotation with sodium laurate, the presence of electrolyte improves Cd2+ recovery and decreases the thickness of the water sheaths around the gas bubbles. The interpretation of the results is based on the exchange of the collector counterions as well as on the properties of the reaction products.