Selective chemical extraction and separation of Mn, Fe oxides and organic material in natural surface coatings: application to the study of trace metal adsorption mechanism in aquatic environments

To reveal the relative contribution to adsorption of trace metal on manganese and iron oxides and organic material in natural surface coatings (biofilms and associated minerals) in aquatic environments, a selective chemical extraction technique was employed to separate the metal oxides and organic material prior to the adsorption of trace metals. Surface coatings were collected on glass slides in the surface waters of Nanhu Lake (Changchun, Jilin Province, PR China) as an example. After screening different kinds of conventional extractants of manganese and iron oxides and organic materials used for separation of heavy metals in soil and sediment, hydroxyl-amine hydrochloride (NH2OH . HCl) was used to extract manganese brides, sodium dithionite (Na2S2O4) was used to extract both manganese and iron oxides and nitric acid (HNO3) was used to remove all of the materials. Under the experimental conditions, the target components were extracted with efficiencies above 91%. This peparation was important for further research of adsorption mechanism of trace metal on them. (C) 2001 Elsevier Science B.V. All rights reserved.