Influence of ethyl xanthate on the wettability and surface free energy of galena

Abstract

The contact angles of water (W), glycerol (G), formamide (F), diiodomethane (D) and 1,1,2,2-tetrabromoethane (T) were measured on a non-oxidized and oxidized surface of galena previously covered with a potassium ethyl xanthate film formed from aqueous solutions at different concentrations. Then, using the obtained values of the contact angle, the Lifshitz–van der Waals component and electron-acceptor and electron-donor parameters of the Lewis acid–base component of the surface free energy 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 surface treatment after adsorption of ethyl xanthate on its surface and results from both apolar and polar intermolecular interactions. The contribution of these interactions in the surface free energy of galena depends on the concentration of potassium ethyl xanthate solution used for film formation and the state of the galena surface (non-oxidized or oxidized). With the increase of ethyl xanthate concentration in the solution from which the film was formed, the Lifshitz–van der Waals component increases or decreases a little depending on whether or not the surface 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 practically does not depend on the concentration of the potassium ethyl xanthate solution in contact with galena. The changes of the electron-donor parameter of the acid–base component depend on the state of the galena surface, the concentration of the potassium ethyl xanthate solutions and the way of galena surface treatment after adsorption. It is interesting that the total surface free energy, both of non-oxidized and oxidized galena, does not practically depend on the concentration of potassium ethyl xanthate in aqueous solution from which the film was formed.