Extraction of Radioelement using Innovative Functionalized Membranes – MEMFIS

The treatment of effluent and wastewater has become a major environmental concern of our society. Whatever the application area, regulations on wastewater discharges are becoming more severe and require efficient reprocessing technologies. This must take into account the recycling or conditioning of some products and water reuse after decontamination. Perhaps more than any other industrial activity, a strong requirement for the nuclear industry is to reach radioactive releases as low as possible with the best technology available at an economically acceptable cost. Thus many industrial and nuclear scientists are now mobilized to improve the efficiency of decontamination processes of radioactive effluents. In France, the activity of these effluents after decontamination is far below current standards, and is still decreasing since few years. However, to reach the ambitious objective of an activity of the waste close to zero, it is necessary to develop innovative treatment processes. The needs of the nuclear industry waste water treatment concern (i) fixed installations such as reactors and power stations, liquid waste treatment (STEL) of plants or research centres (ii) more specific applications to specific waste, and often abroad. In general, treatment of effluent requires particle filtration and extraction of a series of radionuclides such as cesium, cobalt, nickel, etc., by ion exchange resins, or by a selective co-precipitation. The current processes of extraction, simple and robust present some drawbacks to solve: for example, in the case of ion exchange resins, their capacity is limited, and the water retains some activity mainly due to 60Co. On the other hand the radioactive nature of extracted elements may cause a deterioration of the resin in storage conditions. In the case of coprecipitation process, the amount of waste generated is high and the recovery of particles after precipitation remains a limiting step.
The objective of this project is to provide a method of complexation-filtration membrane for decontamination of radioactive waste, competitive with current processes. The use of membrane process is actually interesting in order to decrease effluent volume and to improve the waste confinement. The originality of this project is that in addition to filtering of particles this process also allow thanks to the membrane’s functionalization extracting soluble components. The development of functionalized membrane technology implies a field of interdisciplinary research involving chemists for the synthesis of new materials, physical chemists for the characterization of these materials and description of their transport properties, but also specialist’s chemical engineering to optimize the implementation process on an industrial scale. The known-how and experience of the different teams and partners can achieve this goal: for the “academic” point of view a chemist’s team will be responsible for the synthesis of materials and their functionalization, the second research team of the consortium will follow their characterization; regarding the industrial side, an industrial specialist of filtration membranes and an industrial active in the field of decontamination of radioactive waste are both partners of this project. Recent developments made by our teams at the laboratory scale in using of solid supports functionalized with specific Cs ion-exchange groups, allow us to look at this project from their implementation on an industrial scale, with industrial teams project partners. The generalization of this concept to other radioisotopes is a scientific and technological challenge to be met if the project is accepted.