Humic acids (HA) Lenka Tuhovčáková & Marcela Lagová ©2005

Summary Humic acid Humic acid Properties Properties Structure Structure Preparation Preparation Environmental impact Environmental impact

What are humic acids? Unbelievable and amazing „chemical stuff“! Unbelievable and amazing „chemical stuff“! Natural organic substances, situated mainly in water, soil, carbon and water sediments. 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. Stuffs of the unique properties and structure, which were not still exactly described despite large experimentals. Substances aren´t the chemical individuals, they consist from the mixture of compounds

Division of humin stuffs Humin stuff Humic acid Humin acidFulvin acid Hemato- melanic Acid Salt of humic acid LigninHuminHumic coal

Characteristics dark brown to black in colordark brown to black in color

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. Is not soluble in water 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 Composed from: 40 – 60% carbon, 30 – 50% oxygen, 4 – 5 % hydrogen, 1 – 4% nitrogen, 1- 2% sulphur and 0 – 0,3% phosphorus

Important component of humic matters Important component of humic matters HA can bond hydrophobic and hydrophilic stuffs. HA can bond hydrophobic and hydrophilic stuffs. Help to improve soil fertility, its physical properties facilitate transport of nutrients. 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. 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. 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)

Contains from aromatic and aliphatic structures, both extensively substituted with oxygen - containing functional groups. 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. 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. Thought to be complex aromatic macromolecules with amino acids, amino sugars, peptides, aliphatic compounds involved in linkages between the aromatic groups.

Preparation of HA From lignit and oxihumolit. Higher yield of HA is from oxihumolit. From lignit and oxihumolit. Higher yield of HA is from oxihumolit. Yield must be deashed and repurified by mixture of hydrochloric and hydrofluoric acid. Yield must be deashed and repurified by mixture of hydrochloric and hydrofluoric acid.

The role of humic acid in the environment Are essential but incompletely understood sorptive and metal binding biopolymers in animals, plants, soils and sediments. Are essential but incompletely understood sorptive and metal binding biopolymers in animals, plants, soils and sediments. Continue to be intensively studied - their environmental importance. Continue to be intensively studied - their environmental importance. HS have important physiological properties, many of them are attributed to their sorptive properties. 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.

Are usually found near lung tumors in coal miners and smokers. 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. 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. 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 Internet Our lab diary Diploma works: Renáta Superatová, Květuše Chvátalová Presentaitions of doc. Klučáková and doc. Pekař

Dictionary humic acids humic acids decomposing tissues decomposing tissues lyes lyes soil fertility soil fertility facilitate facilitate clay clay peat peat extensively extensively variously variously involved in involved in yield yield uterine cancer uterine cancer ferric iron ferric iron ferrous iron ferrous iron variety variety huminové kyseliny rozkládající se tkáně louh půdní úrodnost ulehčit jíl rašelina značně různě zapletený (do) výtěžek rakovina dělohy trojmocné Fe dvojmocné Fe druh