Transcript lagovaprojektorhuminky2

Humic acids
(HA)
Lenka Tuhovčáková
&
Marcela Lagová
©
2005
Summary
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Humic acid
Properties
Structure
Preparation
Environmental
impact
What are humic acids?
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Unbelievable and amazing
„chemical stuff“!
Natural organic
substances, situated
mainly in water, soil,
carbon and water
sediments.
Stuffs of the unique
properties and structure,
which were not still
exactly described
despite large
experimentals.
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Substances aren´t the
chemical individuals, they
consist from the mixture
of compounds
Division of humin stuffs
Humin stuff
Humin acid
Humic acid
Salt of
humic
acid
Fulvin acid
Hematomelanic
Acid
Lignin
Humin
Humic coal
Characteristics
•dark brown to black in color
Is not soluble in water
 Composed from: 40 – 60% carbon, 30 – 50%
oxygen, 4 – 5 % hydrogen, 1 – 4% nitrogen,
1- 2% sulphur and 0 – 0,3% phosphorus
 Issue from plant´s and animal´s decomposing
tissues.
 Soluble in lyes, salts and organic solvents.
 Molecular weight, structure, quantity and
position functional groups depend on origin and
age of material.
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Important component of humic matters
HA can bond hydrophobic and hydrophilic
stuffs.
Help to improve soil fertility, its physical
properties facilitate transport of nutrients.
Min volume of HA is in sand, clay max volume is
in brown carbon and lignit.
Interesting: the highest volume of HA (over
80%) is in peat.
 Some hypotetical chemical formulas of humic
acids describe position of characteristic
functional groups.
Hypotetical chemical structure of humic acids
(Buffle´s model)
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Contains from aromatic and aliphatic
structures, both extensively substituted with
oxygen - containing functional groups.
Hypothetical structure for humic acid, shown in
figure, contains free and bound phenolic OH
groups, quinone structures, nitrogen and oxygen
as bridge units and carboxylic groups variously
placed on aromatic rings.
Thought to be complex aromatic
macromolecules with amino acids, amino sugars,
peptides, aliphatic compounds involved in
linkages between the aromatic groups.
Preparation of HA
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From lignit and
oxihumolit. Higher yield
of HA is from
oxihumolit.
Yield must be deashed
and repurified by
mixture of hydrochloric
and hydrofluoric acid.
The role of humic acid in the
environment
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Are essential but incompletely understood sorptive
and metal binding biopolymers in animals, plants,
soils and sediments.
Continue to be intensively studied - their
environmental importance.
HS have important physiological properties, many of
them are attributed to their sorptive properties.
Polyaromatic hydrocarbons, pesticides are adsorbed
on HA surfaces.
HA is therapeutic against uterine cancer in
laboratory animals.
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Are usually found near lung tumors in coal miners
and smokers.
Our studies show that HA is a powerful reductant
and an excellent chelating agent.
The combination of these effects creates a
chemical systems that can activate transition
metals. Ferric iron is chelated and reduced to
ferrous iron.
Effects of work of ferrous iron in the H.A. matrix is
similar for copper and variety of transition metals.
Used literature
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Internet
Our lab diary
Diploma works:
Renáta Superatová,
Květuše Chvátalová
Presentaitions of doc.
Klučáková and doc.
Pekař
Dictionary
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humic acids
decomposing tissues
lyes
soil fertility
facilitate
clay
peat
extensively
variously
involved in
yield
uterine cancer
ferric iron
ferrous iron
variety
huminové kyseliny
rozkládající se tkáně
louh
půdní úrodnost
ulehčit
jíl
rašelina
značně
různě
zapletený (do)
výtěžek
rakovina dělohy
trojmocné Fe
dvojmocné Fe
druh