organo clay complexes study ( fractionationtechniques and characterisation)

2. ADVANCES IN FRACTIONATION AND
CHARACTERIZATION OF NATURALLY OCCURING
ORGANO-CLAY COMPLEXES
Sankhadip Das
Roll No -10538
Division of Soil Science and Agricultural Chemistry
Indian Agricultural Research Institute
New Delhi-110012

3. 1. Introduction
2. Nature of organo-clay complexes
3. Fractionation of organo-clay complexes
4. Characterization of organo-clay complexes
5. Research Findings
6. Conclusion
7. Path ahead
Contents

4. Introduction
The soil clay-humus complex plays an important role in forming the
structure and fertility of agricultural soils
Stevenson (1982)
“Clay-associated organic matter as all organic matter present in
the clay-sized fraction, both free organic particles and organic
matter bound to minerals
Wattel-Koekkoek & Buurman (2004)
‘Primary structure of soils as defined by the soil texture resulting
from the association of organic matter (OM) with primary mineral
particles, and as complexes that are isolated ‘after complete
dispersion of soils’
Christensen (1996)
Secondary organo-clay complexes were defined as the
aggregation of several primary organo-mineral complexes

5. Nature of Organo Clay Complexes
 Clay-organic complexes enriched in top soils are the main reservoirs of
plant nutrients.
Organo-clay complexes are the adsorption products between the
organic cations anions or molecules transfered from solutions , liquid or
gaseous states to clay surfaces generally due to the physical or chemical
bonds ( long or short range respectively).
Organo-clay complexes are conglomerate soil colloid in which clay,
oxides/hydroxides (including sesquioxides and allophanes) and humic
material remain associated.
The types and amount of layer silicates, intercalation of OM, content of
pedogenic oxides, soil properties, vegeatation , etc are decisive in the
formation of clay-organic bonds.

6. Fractionation of Naturally
Occurring Organo - clay
complexes

7. Physical Fractionation Techniques
 Density Fractionation
Aggregate fractionation
Particle size fractionation
 Centrifugation
Gravity sedimentation
High-gradient magnetic separation (HGMS)
Size exclusion chromatography
Physical fractionation methods in the strict sense include size and density separation of
primary organo–mineral complexes in whole soil, which means that aggregates are not
considered (Christensen, 1992).

8. Chemical fractionation techniques
 Extraction of Soil Organic Matter in aqueous
solutions with and without electrolytes
 By use of organic solvents
 By hydrolysis of organic matter
 By oxidation of organic matter

9. Characterization of Organo- clay
complexes
 13C nuclear magnetic resonance spectrocopy (13C-
NMR)
 X ray diffraction analysis
 Transmission electron microscopy analysis
 Scanning electron microscopy analysis
 Near -edge X ray absorption fine structure spectroscopy
 Fourier transform infrared spectroscopy (FTIR)
 Thermal analysis .

10. Nuclear magnetic resonance spectroscopy
The first attempt to use nuclear
magnetic resonance (NMR)
spectroscopy for structural
characterization of soil humic
substances was reported by
Barton and Schnitzer (1963) and
Neyroud and Schnitzer (1972).
13C-NMR can used to determine
the number of non-equivalent
carbons and to identify the types
of carbon atoms(methyl,
methylene, aromatic,
carbonyl….) which may present
in compound.

11. When energy in the form of radiofrequency is applied
When applied frequency is equal to precessional frequency
Absorption of energy occurs
Nucleus is in resonance
NMR signal is recorded
Principle of NMR

12. Thermal Analysis
Thermal method of analysis are group of techniques in which changes
in physical and /or chemical properties of a substance are measured as
a function of temperature, while substance is subjected to controlled
temperature programmed

13. Mass
ΔT ΔH
Deform
ation
Gas
decompose
Thermal
diffusivity
Volume
Physical
Properties
Differential
Scanning
Analysis
Differential
Thermal
Analysis
Dynamic
Mechanical
Analysis
Laser Flash
Analysis
Dilatomet
ry
Evolved Gas
Analysis
Thermo Gravimetric
Analysis

14. Techniques most commonly used :
1. Thermo-microscopy
2. Differential thermal
analysis
3. Differential scanning
calorimetry 4. Thermo-gravimetry

15. Thermo gravimetric analysis (TGA)
It is an analysis, the mass of sample is recorded
continuously as its temperature is increased linearly from
ambient to high temperature.
Mass of material a functions of temperature.
Processes occurring without change in mass
(e.g.- Physical transitions ) cannot be studied by TG

16. Differential Thermal Analysis(DTA)
 Heat absorbed or emitted by sample is observed by
measuring the temperature difference between that sample
and reference compound as temperature of both are increased.
ΔT =TS -Tr as function of Temperature.
Temperature of furnace

17. The technique was developed by E.S. Watson and M.J. O'Neill in
1960, and introduced commercially at the Pittsburgh Conference
on Analytical Chemistry and Applied Spectroscopy in 1963
Differential scanning calorimetry

18.  X-ray diffraction is based on
constructive interference of
monochromatic x-rays and a crystalline
sample.
The interaction of incident rays with the
sample produces constructive interference
when conditions satisfy Bragg’s law.
X ray Diffraction
nλ=2dsinθ

19. Fourier Transformed Infra-Red Spectroscopy
 FTIR collects all wavelengths
simultaneously and scans at once.
 FTIR works based on Michelson
Interferometer which having
Beam splitter
Fixed mirror
Movable mirror

20. Transmission electron microscopy
Transmission electron microscopy (TEM) has
seldom been used in soil organic matter
research, although it showed the variety of OM
morphology found in the clay-sized fraction of
soils (Feller et al., 1991; Chotte et al., 1993)
The first TEM was built by Max Knoll and Ernst
Ruska in 1931, with this group developing the
first TEM with resolution greater than that of
light in 1933 and the first commercial TEM in
1939.

21. Scanning electron microscopy
 The first scanning electron microscope (SEM) debuted in 1938 ( Von
Ardenne) with the first commercial instruments around 1965. Its late
development was due to the electronics involved in "scanning" the
beam of electrons across the sample
 SEMs use an electron beam instead of a beam of light, which is
directed towards the specimen under examination

22. RESEARCH
FINDINGS

23. Study on Differential thermal analysis of Humic acids, clay and
clay humus complexes from various soils
hbkk
(Ahmed et al., 2002)
DTA curves of a) Humic acids, b) clay, and c)clay –
humus complexes from various soils.

24. Effect of rhizosphere on Organo-clay complexation
(Mandal & Datta ,2005)
DRXD analysis of vertisols and Alfisols of Rhizosphere and
Non-rhizosphere

25. (Ahmed et al., 2002)
Study on the comparision of X-ray diffraction patterns of clay
fractions and clay-humus complexes of different soils
Entisol clay
Entisol clay-humus
complex
Mollisol ΙΙ clay-
humus complex
Molliso ll clay
Mollisol Ι clay-
humus complex
Mollisol Ι clay
Alfisol clay
Vertisol clay
Vertisol clay-
humus complex
Alfisol clay-humus
complex
XRD patterns of different soils

26. Impact of tillage and puddling operations on the stability
and physico-chemical properties of clay-humus complexes
Effect of thermal activation (35oC) on changes in organic carbon
content of clay –humus complexes of surface(0-15 cm) and
subsurface soil(15-30 cm ) as affected by long term NT and T
treatments
(Vennila and Datta .,2008)

27. Contd….
Effect of thermal activation (35oC)on changes in organic
carbon content of clay–humus complexes of surface(0-15 cm)
and subsurface soil(15-30 cm ) as affected by long term NP
and P treatments.

28. Solid state 13C NMR spectra of the source HA (SHA) and the unadsorbed HA
(humic acid) fractions after coatingon kaolinites (HAKs), montmorillonites
(HAMs) and goethites (HAGs).
(Ghosh et al ., 2009)
Study of fractionation behavior of Humic Acid upon sorption
on mineral surfaces with varying surface properties.

29. (Ahmed et al., 2002)
TEM images of clays and clay-humus complexes of Entisol (a,b,c) &
Mollisol Ι (d,e,f) respectively

30. Contd…
TEM images of clays and clay-humus complexes of Alfisol(g,h),
Vertisol (i,j) & Mollisol ΙΙ (k,l) respectively

31. Scanning electron microscopy (SEM) images of (a) natural bentonite and (b)
HDTMA-bentonite.
Effect on natural bentonite on modification with
Hexadecyltrimethylammonium(HDTMA) bromide
(Ikhtiyarova et al., 2012)

32. Study on the structural arrangement of Humic acids
isolated from different soils of China
SEM images of the HAs samples.
(Xu et al., 2006)

33. Conclusion
DXRD analysis helped in the better study of stability of the organo-clay
complexes not possible by conventional XRD techniques
The NMR results show a semi quantitative distribution of different carbon
moieties in the original HA and HA fractions obtained after coating.
SEM micrographs was able to show the surface changes of natural
bentonite on application of surfactant resulting in rough appearance of
surface
TEM micrographs helped in the identification of clay minerals of various
nature in different typesof soils
 Stability of organo-clays was seen to be increased with depth in both
puddling and tillage conditions.

34. Path Ahead
More studies on the nature of natural organo -clay complexes are to be
conducted in comparision to synthetic ones
Surfactant studies of humic acids fractions of organo-clay complexes
have to be carried out on a large scale
Studies regarding the influence of soil micro-organisms on the
complexity mechanism between organic matter and clay minerals will
help in greater understanding of the nature of organo-clay complexes
Modern techniques are to be used by replacing the conventional and
traditional techniques in order to get a good understanding on the
characteristics of organo-clay complexes