Influence of Cu2+ and Al3+ ions on Zeta potential change of pectin and protein preparates extracted from sugar beet
2010
Kuljanin, T., Faculty of Technology, Novi Sad (Serbia) | Mišljenović, N., Faculty of Technology, Novi Sad (Serbia) | Koprivica, G., Faculty of Technology, Novi Sad (Serbia) | Lević, Lj., Faculty of Technology, Novi Sad (Serbia) | Filipčev, B., Institute for Food Technology, Novi Sad (Serbia)
All models which are used to describe the behaviour of electrically charged colloidal particles are based on the presence of two basic layers which surround a particle – stationary and diffused layer known as electric double layer. Electrokinetic phenomena are generated by ions in the diffused layer and a potential across the diffused layer where hydrodynamic motion of liquid still exists is a measurable parameter denoted as electrokinetic or Zeta potential. By adding positively charged ions Cu2+ and Al3+, Zeta potential can be reduced to a zero point in which repulsive forces between the colloidal particles stop to exist enabling their aglomeration and coagulation in aqueous solutions. It has been experimentally confirmed in all tested preparations that the addition of Cu2+ and Al3+ ions changed the sign of Zeta potential in such a way that a negative Zeta potential gradually decreased, proportionally to the increased concentrations of these ions. Electrokinetic measurements also showed that changes in the sign of Zeta potential occurred at lower concentrations of coagulant CuSO4 as compared to coagulant Al2(SO4)3. The reason for this is a greater ability of surface complexations of Cu2+ ions and coagulation enhancement effect of SO4 2- ions.
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