Development of a new generation of nano and microfibers extracting materials for elimination of toxic and strategic metals from liquid waste, providing environmental and economic benefits to industrial players.
Environmental pollution of heavy metals by industrial factories is increasingly becoming a central problem. The authorized discharge standards decreased drastically up to level of 1-3 µg/L. Current finishing treatment processes have great difficulty to meet these new standards that is why new technologies should be created. The goal of the Nanoextract program is to develop a new generation of fiber materials having much better metal capture properties than usual ion exchange resins (IERs). The fibers designed during this project will be marketed by AJELIS and represent a strong technical alternative to IERs. These new materials will provide environmental and economic benefits to industrial manufacturers in treatment of their effluents: the discharge metal concentrations will be lowered to the level of µg/L, treatment operations will be faster, the regenerations will be economical in water and chemicals (acids, bases ...). Resulting purified water can be reused on site (Zero Liquid Discharge), or discharged into the natural environment. Fiber materials will contribute to «Factory of the Future« approach: factory that respects the environment.
We developed fiber polymer sorbents of small diameter (1 to 20 µm) having chemical ion- exchange and/or chelating properties identical to those of granular IERs. Compare to IER diameter (several hundred micrometers) our fibers are much smaller and therefore much faster. Different synthetic processes have been explored: electro-spinning (giving the diameter less than 1 micrometer), force-spinning (1 to 3 µm) and post-treatment of textile fibers (20 µm) in order to satisfy different effluent filtration rates.
The main challenge of synthesis of these fibers - high metal capture capacities and above all stability under real use conditions (temperature, pH) - has also been met. Chemical stability of these fibers is important for carrying out their multiple regenerations and is an essential criteria for their industrial application.
To carry out the force-spinning process, we developed our own laboratory device from the accessories of commercial cotton candy machines. Speed, temperature and humidity-controlled centrifugation device made it possible to process the synthesis of nanofibers with very strong metal capture capacities (eg. NFB fiber, copper - 3.26 eq / kg). The difficulty was that they could not meet very high industrial water flow rates because of its thin diameter. Thus we considered a strategy of post-functionalized textile fibers of higher diameter (of the order of 20 to 30 µm). This approach permitted to explore the real industrial cases, to better understand industrial needs and to create different forms of these fiber materials (staple fibers, non-woven felts, wound cartridges). Another objective of the project was to design fibers having stronger chemical selectivities than a simple ion exchange. We integrated some very selective materials into our fibers: organic molecular cages or specific mineral sorbents. Thus the goal of tuning of these fibers for the selective uptake of cesium and arsenic have been achieved.
We developed a range of fibrous sorbent materials capable of satisfying different markets: 1 / “nanofibers”, for purification and chromatographic separation operations which are in great demand in biology without requirements for high flow rates and 2 / «microfibers« for water filtration and metal capture operations at much higher flow rates.
Microfibers are applied today for some water treatment operations (extration of copper, nickel, zinc) by sufrace treatment factories. Nanofiber materials are started to be marketed by AJELIS for its future applications in analytical chamistry.
The patents on nanofiber manufacturing processes filed by the consortium just before and at the start of the project were largely reinforced by the acquisition of new know-how obtained during this program and by the filing of international patent applications.
The articles in an international peer-reviewed journal will be published later. We still remain discreet about the production techniques and applications of these materials for reasons of confidentiality in which AJELIS is engaged with its partners.
Our work was nominated in Start Up Challenge WMF 2018 and INNOVEIT2019 by EIT competitions, Innovation Awards in POLLUTEC2018 competition and obtained an Award in the “Women in Industry Trophies” 2018 competition organized by L'Usine Nouvelle
Pollution related to industrial metal by-products has become a central matter in environmental issues. Moreover, those metals are mainly found in liquid effluents. Indeed, industrials processes generate huge amounts of water containing those metals.
For instance, heavy metals can be found amongst effluents of microelectronics or metallic surface treatment industries, strategic metals such as rare earth metals in the sector of green technologies and radionuclides in the nuclear industry.
Let’s consider metallic surface treatment industrials whose installations follow a “zero liquid discharge” policy but who are still allowed, in accordance with prefectoral decrees, to discharge processed water into the river.
Today, legal concentration standards are in the range of mg/L (Cu 2 mg/L, Zn 1mg/L, Cd 0.2mg/L). However, a lot of pressure from the French and European authorities is put on the legislators to lower those discharge standards in the range of µg/L.
Current industrial processes that carry out finishing water treatments will have difficulties satisfying those new standards. Actually, treatment of liquid effluents by ion exchange resins (IER) is the most common process in use.
The aim of the present program is to develop a new generation of nano / microfiber materials with much better extraction properties than commonly used IER.
Developed by the consortium submitting the project and commercialized by AJELIS, those fibers will be a competitive alternative to IER, both technically and commercially. Beyond their technical efficiency, our new materials will be able to bring environmental and financial benefits to the industrials who are confronted with the treatment of their liquid effluents: the concentration of metals after treatment will fall in the µg/L range; the treatments will be quicker and more environmental friendly (smaller volume of water, of acids …).
To achieve these goals, AJELIS, supported by key industrial players in surface treatment, plans to complete three ‘research’ tasks in this program. The first one will focus on the first generation of extracting fiber (cationic type based on polyacrylic acid PAA), which is ready on a research level. A complete industrial qualification has to be performed. The next task aims to widen the range of fiber materials towards a global offer in comparison with the REI (anionic type, strong and weak). And the following task will tackle the problematic of high selectivity extracting fibers thanks to the use of molecular materials. These three tasks will allow AJELIS to propose a complete set of solution for the treatment of liquid effluents containing heavy metals.
The three ‘research’ tasks, above-mentioned, will fuel a last task which will collect the data and materials to validate them on an industrial scale. This will be performed by mounting technological demonstrators in the factories of industrial players, which have already volunteered. A complete demonstration of the technical parameters, of the material performances and of their economic viability will be done.
The final aim of this program is to collect sufficient data from consumer response for the futher product development.
The project outcomes will be a considerable innovation to the worldwide liquid effluent treatment industry.
Madame Ekaterina SHILOVA (AJELIS)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
CEA Commissariat à l'Energie Atomique et aux Energies Alternatives
ICMMO Université de Paris Sud, ICMMO (UMR 8182)
Help of the ANR 300,186 euros
Beginning and duration of the scientific project: - 36 Months