الفهرس 
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Abstract
Humic acids (HAs) are organic macromolecules resulting from the decomposition of plant depris. They are negatively charged and have a high molecular weight. The humic acids contain large amounts of carbon and functional groups such as COOH and OH. Their high reactivity with metals in soil and aquatic environment are important. Humic acids (HAs) bind heavy metals, pepticides, herbicides and inactive microbial enzymes, biological purification and preparation of drinking water.
Indeed, the complexation properties of HAs are due to their anionic polyelectrolyte character.
The adsorption phenomenon is a significant process in reducing concentration of dissolved heavy metals in natural environment such as soil and aquatic environment.
Recent research indicated that humic acid (HA) has high affinity to magnetite Fe3O4 where the adsorption of humic acid results in polyanionic organic coating on the magnetite and thus altering the surface properties of the particles.