INFLUENCE OF ETHYL XANTHATE ON THE WETTABILITY AND SURFACE FREE-ENERGY OF GALENA

The contact angles of water (W), glycerol (G), formamide (F), diiodome thane, (D) and 1,1,2,2-tetrabromoethane (T) were measured on a non-oxi dized and oxidized surface of galena previously covered with a potassi um ethyl xanthate film formed from aqueous solutions at different conc entrations. Then, using the obtained values of the contact angle, the Lifshitz-van; der Waals component and electron-acceptor and electron-d onor parameters of the Lewis acid-base component of the surface free e nergy of galena covered with ethyl xanthate film were calculated from the modified Young equation. It was found that the surface free energy of the galena/ethyl xanthate film depends on the way of galena surfac e treatment after adsorption of ethyl xanthate on its surface and resu lts from both apolar and polar intermolecular interactions. The contri bution of these interactions in the surface free energy of galena depe nds on the concentration of potassium ethyl xanthate solution used for film formation and the state of the galena surface (non-oxidized or o xidized). With the increase of ethyl xanthate concentration in the sol ution from which the film was formed, the Lifshitz-van der Waals compo nent increases or decreases a little depending on whether or not the s urface galena, after adsorption of ethyl xanthate, was washed by ethyl ether. In all cases, the electron-acceptor parameter of the acid-base component is considerably smaller than the electron-donor one and pra ctically does not depend on the concentration of the potassium ethyl x anthate solution in contact with galena. The changes of the electron-d onor parameter of the acid-base component depend on the state of the g alena surface, the concentration of the potassium ethyl xanthate solut ions and the way of galena surface treatment after adsorption. It is i nteresting that the total surface free energy, both of non-oxidized an d oxidized galena, does not practically depend on the concentration of potassium ethyl xanthate in aqueous solution from which the film was formed. (C) 1997 Elsevier Science B.V.