Nanotechnologies for water analysis and treatment

Applications of nanotechnology for water analysis and treatment

By AVICENN Team – Last Added November 2020

Nanotechnology is used to develop more efficient devices for theanalysis and water treatment. Today, it is difficult to distinguish between applications already on the market and those which are only at the research and development stage. 
Three fields of application of nanotechnology in the field of water can be distinguished:

• La contaminant detection in water
• La water purification
• Soil and water depollution and remediation

Faced with these potential innovations, there is the need to take into account the risks associated with nanomaterials used. This field of application can result in an increase in the presence of manufactured nanomaterials in water and groundwater.

There is also the question of the benefit / risk ratio compared to natural alternatives? Innovation is not only technological, as evidenced by the “nature-based solutions” (NBS) promoted by the United Nations in 2018.

Detection of contaminants in water

Nanotechnologies could have interesting applications in the detection of chemical and biochemical substances in water. In early 2011, the Managing Director of Veolia Environnement's Research Centers considered that "it is very likely in this field [of analysis] that we will soon see an industrialization of nanotechnology for sampling and specific identification in both chemical and microbiological analysis"¹Interview with Mr. Hervé Suty, Chief Executive Officer of Veolia Environnement Research Centers, granted to Richard Varrault (Waternunc), published in 2011.

Water purification

Nanotechnologies can be used to desalinate water, filter pollutants, reduce scale and/or treat wastewater. The processes used or envisaged can combine different types of action:

Filtration of undesirable elements (pollutants, microbes, salt):

This would be the most advanced process, especially for membranes; the filters can consist in particular of:

• carbon nanotubes, to extract viruses and bacteria from water
• nanostructured membranes or on which nanoparticles or nanocoatings are added²See in particular:
  – A project of nanofiltration to reduce micropollutant discharges from the SOTREMO site was deployed in Le Mans
  – Suez Environnement thus participated in a European research project NAMATECH (2009-2012) on the use of nanoparticles for “particularly promising” membranes cf Interview of Mrs. Zdravka Doquang, Head of the Analysis and Health Division at CIRSEE (Suez Environnement), granted to Richard Varrault (Waternunc), published in 2011
  – Veolia Environnement has set up a partnership with the American company NanoH2O aiming to develop membranes for the desalination of seawater: hydrophilic nanoparticles are added to reverse osmosis membranes to promote the passage of water
  – French and American researchers have developed “nanoscopic sieves” cf Cf. Desalinate seawater with nano-scale filters, Carnot Interdisciplinary Laboratory of Burgundy, March 29, 2018
  – Arkema offers in 2018 an ultra filtration process with a fluoropolymer Kynar® PVDF using nanoscale polymer technologies
  – in China, in 2018, a promise of industrial production of nanofiber membranes by 3D printing by Nano Sun, learn more
• attapulgite clay and natural zeolites, available in many parts of the world and featuring natural nano-sized pores
• nanosponges that trap contaminants (these may include polyurethane sponges coated with iron oxide nanoparticles or carbon nanotubes and nanosilver)³See for example: – Nanocellulose sponges against oil spills, Industry and Technology, December 9, 2014. Developed by two researchers, Gilles Sèbe from the LCPO of the University of Bordeaux 1 and Philippe Tingaut, from Empa near Zurich, winners for this sponge of the Innovative Techniques Prize at the Pollutec show.
  - Low energy water purification enabled by nanomaterial-coated sponges, Science for Environment Policy, February 2015 (academic article: Conducting nanosponge electroporation for affordable and highefficiency disinfection of bacteria and viruses in water, Liu, C et al., Nano Letters, 13(9): 4288-93, 2013).

The chemical dissolution of pollutants by oxidation

This with theuse of reactive nanoparticles (titanium, iron oxide for example): the nanocatalysts could be used to chemically break down pollutants. Titanium oxide nanoparticles are, for example, more effective catalysts than titanium oxide on a macroscopic scale and could be used to destroy contaminants by photocatalysis under the effect of UV rays.

Extraction of pollutants by magnetization

Magnetic nanoparticles have a large surface area relative to their volume and can easily form chemical bonds with contaminants transported by water – such as arsenic, mercury, lead, petroleum – and then be extracted using a magnet. Applications are already on the market and there is a lot of research in this area.⁸See in particular:
– Iranian and Finnish researchers have developed a method based on iron oxide nanoparticles to remove nitrate and nitrite from water: cf. Scientists Present Simple Method to Eliminate Nitrate, Nitrite from Water, Soil, Iran Nanotechnology Initiative Council, February 2015
– Researchers at Rice University in the United States have used nanoparticles of rust (iron dioxide) to extract arsenic from water: cf. Low-Field Magnetic Separation of Monodisperse Fe3O4 Nanocrystals, Yavuz CT et al. Science 2006.

Or the elimination of bacteria, through the use of metallic nanoparticles (nanoparticles of silver or copper) with antibacterial properties⁹See Research project: NanoSELECT : Biological nanomaterials to purify water, Sweden, FP7; http://www.cordis.europa.eu/result/rcn/165353_en.html and See also: Hymag'in, a French start-up that manufactures magnetite nanoparticles to purify contaminated water.

Desalination is also an important issue¹⁰See in particular
– in the USA in 2017 a research on a combination of membrane distillation and nanophotonics.
– in 2018 a Chinese publication on a method tested in the laboratory, combining the integration of tellurium nanoparticles in water with plasmonics. The rate of water evaporation is multiplied by three under the effect of the sun's rays. Thus, in 100 seconds the temperature goes from 29°C to 85°C. The creation of nanoparticles is extremely complex and does not offer any possibility of commercialization for the moment..

Depollution and remediation

According to a study carried out for Ademe in 2010, the depollution market was 470 million. One possible solution would be to use iron nanoparticles to clean up the soil. From 2009 to 2012, the NanoFreezes research project mobilized the efforts of researchers from CNRS, INERIS and CEREGE.

Researchers from Gisfi (Scientific Interest Group on Brownfields) reiterated in March 2019 the interest of nanoremediation. Several nanomaterials¹¹Such as nano-zeolites, metal oxides, carbon nanotubes and nanofibers, enzymes and various noble metals (mainly Fe/Pd or Fe/Pt bimetallic nanoparticles) and titanium dioxide… have been explored for the purpose of remediation, but iron nanoparticles remain the most widely used. They make it possible to decontaminate water and soil loaded with chlorinated compounds, which are among the most widespread pollutants. They can be injected into the layers and mixed with soils, down to depths of a dozen meters. In France, as in Canada, studies are funded¹²See in particular:
– Studies continue with Gisfi, the Grand Est region and four European partners (Finland, Greece, Hungary and Italy) in a TANIA program TreAting contamination through Nanoremediation (€1 for work from January 285 to December 735).
– In Canada, the National Institute for Scientific Research (INRS) and the University of Montreal received in 2021 a grant of $338 from the Ministry of Economy and Innovation, for a innovative water decontamination project based on nanomaterials, through the development of new advanced electro-catalytic processes (ECA). .

By using nanocellulose and/or nanochitin membranes, it would be possible to eliminate bacteria in water¹³See the research project: NanoSELECT : Biological nanomaterials to purify water, Sweden, FP7. Likewise, a french start-up manufactures and promotes nano-magnetite to treat water and clean up soil. .

However, the authors point out uncertainties about risks, who are " the regulatory barriers to overcome and concerning the acceptability of these techniques by companies, customers, elected officials and the public“. The introduction of nanoscale ZVIs into the environment may pose a risk to microorganisms which are the base of the food chain. The factors and processes affecting ecotoxicity are complex and the potential impact of engineered nanoparticles on the environment et on human health remains little described today. In order to prevent any negative impact of nanoremediation on the environment, it is essential to conduct a proper assessment, including studies with these nanoparticles at the ecosystem scale. It remains essential to impose a risk-benefit analysis.