Humic acid
Humic acids are found naturally in soil humus, peat and lignite humic substances occurring. The group of several acids formed by partial degradation of residues of dead organisms in the soil. Humic acids have in humus an important function as Bioeffektor and memory for basic nitrogen compounds. Were first described the humic acids by the German chemist Franz Carl Achard. Its salts are called humates.
Features
Humic acids are high molecular chemical compounds that are in addition to other humic substances during the degradation process of biological material formed by " humification ". The molecular weight of humic acids lies 2000-300000 Dalton. They consist mainly of partly decomposed, plant lignin and cellulose, are attached to the often proteins and carbohydrates. It easily degradable substances such as endoxidiert sugar, whereas poorly degradable substances such as lignin, waxes, and fat and protein components remain long contained in the soil and so for example in archeology for the conservation of biological components such as wood, leather, plant fibers, pollen etc. care, but on the other hand, dissolve by the high acidity of the lime in bone rapidly.
So Humus is a dark-brown mass of organic, non- readily degradable substances, which are converted by bacteria, fungi and protozoa not chemically well-defined polymeric materials. In the bottom of the humic acids have an important function as a natural ion exchanger that bind basic nitrogen compounds and release them back in exchange for metallic cations.
Humic acids have, in addition to the carboxyl group ( acid group ) to other functional groups. In water they dissociate into a highly electrically charged polyanion and a corresponding number of cations. In water treatment, humic acids with activated carbon filters, special ion exchange filters ( Scavengerfiltern ) or membrane technologies (reverse osmosis) away, as the water would otherwise be colored yellow or downstream ion exchange resins would be harmed by " fouling".
Composition / fractionation
According to the different solubility of humic substances can be fractionated ( chemically split ) are. After FJ Stevenson, a distinction is water-soluble fulvic acids ( molecular weight < 3000 Da) of the water-insoluble but alkali-soluble humic acids and the water-and alkali- humins. From the humic acids can be separated by dissolving the alcohol Hymatomelansäuren. Furthermore, it is possible by means of special separation processes separation of the humic acids in gray and Braunhuminsäuren. Humic acids can be derived from their alkaline solutions precipitate with dilute mineral acids.
The International Humic Substances Society ( IHSS, German: International Huminstoffgesellschaft ) deals with the chemistry, properties and application of humic acids, in particular in the environment, water management and agriculture, while the International moor and Torfgesellschaft ( IMTG ) is primarily concerned with the research and Application of humic and fulvic acids from peat in agriculture ( horticulture) but also in medicine ( Balneology ) busy.