4. EMULSIONS
Emulsion Type and Means of
Detection:
1) Dilution Test:
- o/w emulsion can be diluted
with water.
- w/o emulsion can be diluted
with oil.
Background
Bound water
Unbound water
Non hygroscopic and hygroscopic
material
Latent heat
5. Background
Hygroscopic
Materials
Water in:
-fine capillaries
-cell and fibre walls
-physical interaction
Bound
water
Vapour pressure
of wet solids is
Less than the
vapour pressure
of pure water
Non-hydroscopic
materials
Water in void
spaces
Unbound
water
Vapour pressure
of wet solids is equal
to vapour
Pressure of pure
water
Contains Condition
Contains Condition
6. Preamble
Equilibrium moisture content (EMC): It is
the amount of water present in the solid
which exerts a vapour pressure equal to
the vapour pressure of the atmosphere
surrounding it.
Free moisture content (FMC):
Free moisture content (FMC) is the amount
of water that is free (easy) to evaporate
from the solid surface.
9. Rate of relationship
mass of water in sample (kg)
% Loss on drying = -------------------------------------- x 100
(LOD) total mass of wet sample (kg)
mass of water in sample (kg)
% Moisture content = ------------------------------------- x 100
(MC) mass of the dry sample (kg)
weight of water lost from sample(kg)
Drying rate = --------------------------------------------------------------
Time(h) x weight of the dry solid(kg)
10. Drying rate curve
Drying rate curve: The moisture at point ‘C’ is called
CMC = Critical moisture content, E= EMC
Free Moisture content
Drying
Rate
A’
A
B C
D
E
AB= Initial adjustment,
BC = Constant rate period,
CD=First falling period,
DE= second falling period,
