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Superparamagnetic composite particles with specific surface modifications for the continuous separation of heavy metal ions from water (PARAMAGSEP)


Super-paramagnetic composite particles (SPMC) are particles in a µm- or sub µm-range with embedded iron oxide nano-particles. These composite particles are magnetised under the influence of a magnetic field, but lose their magnetisation when the magnetic field is switched off. The objective of the PARAMAGSEP-project was to develop a new continuous flow magnetic separation technology for the cleaning of wastewater using surface modified SPMC in order to remove hazardous heavy metal ions from wastewater. The general approach for the material and process development was the use of wet chemical routes for the synthesis and processing of nm-scaled particles and stabilised suspensions of iron oxide particles. These magnetic particles could then be transferred into composite particles by enclosure in a silica matrix. The following surface modification with metal ion-complexing agents led to a re-suspendable material that was able to act as a magnetic separation material with a variable selectivity and capacity for hazardous heavy metal ions in wastewater. The selectivity and capacity of the obtained super-paramagnetic composite particles still have potential for further development. After complexation and separation of the ion-loaded SPMC, the complex could be loosened by a change in pH or in ionic environment. By this route, a separation of heavy metal ions from wastewater could be shown. The separated heavy metal ions could be either disposed in a highly concentrated form or they could be recovered by different state-of-the-art-techniques (e.g. electrodeposition). The project ended up in a bench-scale demonstrator unit with complexation, separation, decomplexation and recovering or recycling of raw materials. The results of the project will be used by HIMTECH, IET, ARCON MINES Limited and Carlow Radiators Ltd. to improve the effectiveness of their own waste treatment procedure and to improve the environmental aspects of this technology by recycling or recovering of raw materials.