Applications of adsorbents containing iron oxide or iron hydroxide are well known in different water cleaning processes. Typical examples are the removal of heavy metal compounds (usually arsenate, vanadate) from contaminated ground water, landfill leachate or mining and industrial waste water as well as the reduction of nutrient enrichment (eutrophication) in surface water bodies by removing phosphate. Commercially available products are either synthetic iron hydroxides (GEH 101, GEH Wasserchemie GmbH; Bayoxide® E 33/E IN 20, Lanxess Deutschland GmbH), produced using iron salts or iron scrap as raw material, or based on respective material obtained as by-product in drinking water treatment (e.g. FerroSorp®Plus; P.U.S. Produktions- und Umweltservice GmbH). They are usually characterised by a defined chemical structure and high loading capacities, but the raw materials are limited – leading to higher costs of the products.
Iron containing compounds on the other hand are also an issue of serious environmental pollution in different former mining areas, like parts of Lusatia in Germany. Open cast brown coal mining – associated with ground water management and the destruction of the natural soil fabric – resulted in the oxidation of geogenic pyrite deposit. After termination of the mining activities subsequent processes lead to a mobilization of the iron species as well as the formation of iron hydroxides. In order to prevent accumulation of the iron species in the surface water bodies (lakes and rivers, like the Spree) and additional negative environmental impacts, the water is treated in industrial plants producing several millions of m3 iron hydroxide containing sludge every year.
Using these by-products as raw material for the production of iron hydroxide containing adsorbents was the core issue of a joint research project of partners from industry and research institutions. Main objective was a product with advantageous properties by obtaining a hierarchical pore system and a high porosity in a microstructured agglomerate....
Session: L9 - Depth Filtration and Adsorption - Applications
Day: 14 March 2018
Time: 13:00 - 14:15 h