Wettability, minerals, adsorption

Thus, were the xanthate ion itself to adsorb and retain its charge, lateral repulsion would make it impossible for the surface coverage on the mineral to be a high one, and the desired hydrophobicity of the surface would not be achieved. In the electrochemical mechanism described by Salami and Nixon, the adsorption can become a charge-transfer reaction, continuing by the participation of oxygen until the surface is fully covered with dixanthate (and hence wettable). The mechanism is thus an electrochemical oxidation. 

The wettability of reservoir rocks can be altered by the adsorption of polar compounds or the deposition of organic material such as asphaltenes in the crude oil. Wettability alteration is determined by the interaction of oil constituents, mineral surface, and brine chemistry including ionic composition and pH. Any extraneous substance such as artificial surfactants that changes the mineral surface will change the wettability of the rock and consequently the flow of fluids inside the reservoir. 

Understanding of the structure of the adsorbed surfactant and polymer layers at a molecular level is helpful for improving various interfacial processes by manipulating the adsorbed layers for optimum configurational characteristics. Until recently, methods of surface characterization were limited to the measurement of macroscopic properties like adsorption density, zeta-potential and wettability. Such studies, while being helpful to provide an insight into the mechanisms, could not yield any direct information on the nanoscopic characteristics of the adsorbed species. Recently, a number of spectroscopic techniques such as fluorescence, electron spin resonance, infrared and Raman have been successfully applied to probe the microstructure of the adsorbed layers of surfactants and polymers at mineral-solution interfaces. 

The process of froth flotation for the separation of minerals exploits the fact that either minerals differ naturally in their degree of wettability by surfactant solutions or their surface properties can be modified by adsorption. When air is blown through a suspension of finely ground ore in an appropriate surfactant solution, those particles which have the relevant surface properties become... 

---