The movement ( migration) of the dispersion medium of colloidal solution , under the influence of electrical field, when dispersed particles are prevented from moving is known as ELECTROOSMOSIS. It is basically a drying technique . It is used to dewatering a substance or a colloidal solution electrically.

1. ELECTROOSMOSIS
Presented By:
WISHAL
BUTT

2. DEFINITION
• The movement ( migration) of the
dispersion medium of colloidal solution ,
under the influence of electrical field, when
dispersed particles are prevented from
moving is known as ELECTROOSMOSIS.

3. HISTORY
• Electro-osmotic flow
was first reported in
1807 by F. Friedrich
Reuss.
• Dewatering of clay.

4. Electro-osmosis
was discovered
independently in
1814 by the
English chemist
Robert Porrett Jr

5. PURPOSE
• It is basically a drying technique .
• It is used to dewatering a substance or a
colloidal solution electrically.

6. INSTRUMENTATION
• The electro-osmosis is carried out in a specially
designed apparatus.
• The apparatus consists of a bigger tube having
two side tubes T and T’ attached to its ends.
• The bigger tube is divided into three
compartments A, B and C by means of two semi-
permeable membranes.
• A tube carrying a stop-cock is attached to the
central compartment A.
• Two platinum electrodes are inserted in the outer
compartments B and C.

7. INSTRUMENTATION

8. WORKING
• A colloidal dispersion is placed in the central
compartment A.
• the outer compartments B and C are filled with
water. The water in compartments B and C also
extends to the side tube T and T/.
• The function of membrane is to prevent the
movement of colloidal particles.
• when a potential difference is applied across the
electrodes held close to the membranes in the
compartment B and C, dispersion medium begins
to move.

9. Cont…..
• If the particles carry positive charge, the
dispersion medium would start moving towards
the anode and the level of water in the side tube
T would be seen to rise.
• indicating the presence of negative charge on the
dispersion medium.
• If the particles carry negative charge, the
dispersion medium would be seen to move
towards cathode and water in the side tube T
would start rising.

10. Step-1:
A long tube , having two side tubes, T & T’

11. STEP- 2:
Colloidal dispersion is separated from chamber Y & Z by the
semipermeable membrane.

12. STEP-3:
H₂O is filled in compartment y & Z

13. STEP-4:
Potential difference is applied.

14. IMPORTANT TERMS
• ZETA POTENTIAL:
zeta potential is the potential difference
between the dispersion medium and the
stationary layer of fluid attached to the
dispersed particle.

15. RELATION
Zeta potential can b measured by the process of electroosmosis
as well

16. • SEMIPERMEABLE:
• A semipermeable membrane is a membrane
that only allows certain types of particles to
move through it under certain conditions.

17. APPLICATIONS
1. Dewatering of moist clay:
• soft clay whose moisture content cannot be
reduced by conventional dewatering method
, can be reduced by electroosmosis.
• Electrodes are fixed in soil & current supplied
& water moves from anode to cathode.
• An ejector well system is used as cathode
which collects & removes water from the
ground.

19. 2. Removal of water from peat
3. Drying of dye paste:

20. DIFFERENCE
ELECTROOSMOSIS
• liquid with free charge
move.
• Semipermeable membrane
present.
• Dispersed phase is
stationary.
ELECTROPHORESIS
• charged solid particles
move
• Semipermeable membrane
absent.
• Dispersed phase is not
stationary.