Electrochemical properties of asphaltene particles in aqueous solutions

The electrical properties of colloidal asphaltene/water solution interface were determined by carrying out the potentiometric titration and electrokin etic measurements. Asphaltenes in aqueous solutions exhibit typical organic colloid properties i.e. surface charge and electrophoretic mobility. It wa s considered that the surface charge at the asphaltene particles is a resul t of protonation and dissociation reactions of surface functional groups. O n the base of the surface charge density data vs. pH the surface reaction c onstants were calculated by numerical method. The agreement of these values with calculated ones, on the base of zeta potential data, is noticeable. T he characteristic feature of the investigated systems is the maximum, appea ring on the curve zeta potential vs. electrolyte concentration. This behavi our is explained by ,,hair layer" structure of the asphaltene surface.