2. Clay
Clay is a naturally occurring material composed
primarily of fine grained minerals, which shows
plasticity through a variable range of water
content and which can be hardened when dried
or fired. Clay deposits are mostly composed of
clay minerals (phyllosilicate minerals) and
variable amount of water trapped in the mineral.
Clay materials have been investigated because of
their importance in agriculture, in ceramics, in
construction and other uses.
3. GENERAL STRUCTURE OF CLAY
Figure -1- (a) Silica tetrahedron
Figure- 1- (b) Alumina octahedral
6. There are four main groups of clays :
1- Kaolinite.
2-Montmottilonite-smectitie:the essential nanoclay
raw material , a 2 to 1 layered smectite clay mineral
with a platey structure.
3-Illite.
4- Chlorite.
GROUPS OF CLAYS
7. Nano-clay
Nano clays are minerals which have a high aspect ratio
and with at least one dimension of the particle in the
nanometer range. The purity and cation
exchange capacity of the nano-clay are also critical
characteristics. The purity is important in achieving
maximum increases in mechanical properties and
achieving optimum clarity for use in films. Impurities
act as stress concentrators, resulting in poor impact
and tensile properties. The cation exchange capacity
provides the surface activity necessary for acceptance
of modifiers or surface treatments.
8. Figure 4. Crystal lattice structure of
montmorillonite nanoclay.
The nanoclay used is a surface
modified montmorillonite mineral.
The general formula for class of
montmorillonite is
(Na,Ca)0.33(Al2y,Mgy)Si4O10(OH)2
·nH2O.
Figure 4 shows the crystal lattice
structure of montmorillonite
nanoclay:
11. APPLICATION OF NANOCLAY
1.Nanoclay is used in the ink formulation: It helps to
adjust the consistency of printing inks to the desired
value, avoiding pigment sedimentation, providing
good colour distribution, obtaining desired film
thickness, etc. by incorporation of small amount of
organically modified layered silicate.
2.Thickening lubricating oils with nanoclays can
produce especially high temperature resistant
lubricating greases.
12. 3.The performance of cosmetics is enhanced
by the use of nanoclays and they allow good
colour retention and coverage for nail
lacquers, lipsticks and eye shadows.
Fields of application (paints, inks, greases and cosmetics).
13. 4.Waste water treatment:
.
The use of nanoclays in wastewater treatment has become
common in industry today. Nanoclays exhibit a synergistic
effect with many commonly utilized water treatment unit
processes including granular-activated charcoal, reverse
osmosis, and air strippers. Granular-activated carbon is
particularly effective at removing a large range of organic
molecules from water, however, is very poor for removing
large molecules such as humic acid and wastewaters
containing emulsified oil and grease. Nanoclays have proven
to be the technology of choice for treating oily wastewaters.
14. 5.Nanoclay as drug vehicle:: nanoclays as drug
vehicle for controlled release of drug is one
of the born age area in medicinal
application, nanoclays have great potential
as compared to polymer and carbon
nanotubes for drug delivery
applications.