Humic acid is an amorphous, multi-polymer mixtures, the molecular structure of their authenticity currently do not know. Usually black or brown colloidal state, the dry gel fracture in shape shell, of a density between 1.330 ~ 1.448g/cm3, with a large surface area, in dilute aqueous solution as water under non-sticky. The following are some basic properties of humic acid.
More or less soluble humic acid dissolved in acid, alkali, salt, water and some organic solvents, which can be used as these substances humic acid extraction agent. These extraction agents are generally divided into a basic substance (eg, KOH, NH4OH, NaCO3, Na4P2O7, etc.), neutral salts (NaF, Na2C2O4), weakly acidic substance (such as oxalic acid, citric acid, benzoic acid, etc.), an organic solvent (such as ethanol, ketones, pyridine, etc.) and a mixed solution (NaOH and Na4P2O7) five.
Humic acid is a hydrophilic colloidal properties colloid, a true solution at low concentrations, no viscosity; while at high concentrations is known as a colloidal solution or dispersion, showing colloidal properties. When adding acids or a high concentration of salt solution can agglomerate, dilute hydrochloric acid or sulfuric acid is generally used to maintain the pH between 3 to 4, this solution was still will be able to quickly precipitate floc.
Humic acid molecular structure of a carboxyl group and a phenolic hydroxyl group, it has a weak acid. Therefore humic acid with carbonates, acetates quantitative reaction. Humic acid and its salts, a buffer solution consisting, soil pH can be adjusted, so that the pH in the appropriate crop growth conditions.
Ion exchange some of the humic acid molecule functional groups such as carboxyl group-COOH may be the H + Na +, K +, NH4 + and other metal ions displace weak acid generated, and therefore have a high ion exchange capacity. Humic acid ion exchange capacity of pH, when the pH increased from 4.5 to 8.1, the ion exchange capacity of humic acid from 1.7mmol / g to 5.9mmol / g.
Complexation properties of humic acid contains a lot of the functional groups can be used with some metal ions (eg Al3 +, Fe2 +, Ca2 +, Cu2 +, Cr3 +, etc.) to form complexes or chelates. Humic acid structure, metal complex or chelate in a functional group is a carboxyl group and a phenolic hydroxyl group generally, there may be a carbonyl group and an amine.
Physiological activity of humic acid to promote physical activity refers to the ability of the organism physiological activities.
Physiological activity of humic acid on the performance of the plant to stimulate plant growth and metabolism, improve quality and enhance plant seeds resilience, but the concentration of humic acid and humic acid molecular size of a relationship.