Abbasi - Colorant Manufacturing and Environmental science department, Institute for Colorants, Paints and Coating – Tehran – Iran
Razzaghi asl - Colorant Manufacturing and Environmental science department, Institute for Colorants, Paints and Coating – Tehran – Iran
Naghizadeh - Tirtash Education and Research Center – Behshahr – Iran.
Hosseini - Tirtash Education and Research Center – Behshahr – Iran.

Heavy metals are one of the most environmental contaminants .Removal of these elements is highly significant from the environmental aspect .Humic acid is a polycyclic compound finding in soil, coal and deteriorated plants. This compound is highly capable of binding metals due to the presence of chelating groups in its structure. Humic acid used in this experiment was extracted from peat German soil and elemental analysis was determined for it .Versatile methods have been applied for removal of heavy metals. In this research the interaction of humic acid with Pb2+, Co2+ , Cd2+ , Ag+ and Ba2+ ions in their aqueous solutions was investigated by spectrophotometry. Results revealed that the metal affinities for humic acid was in the order of Co2+ > Pb2+ > Cd2+> Ag+ > Ba2+. For reliability of determined residual cation concentrations, the measurements were performed in acidic media to avoid precipitation of cations in the form of hydroxide thus increasing the metal removal from the solution. Also effective factors as initial metal ion concentration, pH, reaction time, chelate concentration, ionic strength and their interactions were evaluated by experimental design

Humic acid, Heavy metals, Removal, Spectrophotometery