Hello Edwilde Yoplac,

to remove cations from water you need some basic/anionic material, to which the cations can bind to.

In analogy to some polyquaternium compounds (i.e. PQ-10), which use a biosourced raw material (cellulose) and are chemically modified to be positively charged, you could use a similar material, but charge it negatively.

Some of thepositively charged PQ-compounds are used to flocculate anionically charged particles in waste water. If you deprotonate the hydroxy groups of (nano)cellulose you should obtain a (nanoscaled) biobased material, which should bind to cations of As.

In the biosynthesis of nanomaterials, there are various materials that can be used to improve the quality of surface waters. Some of these materials include:

Metal-based nanomaterials: Nanoscale particles of metals like iron, silver, and titanium dioxide are commonly used for water treatment. These materials have high surface area-to-volume ratios, allowing for enhanced adsorption and catalytic activity. They can effectively remove pollutants such as heavy metals, organic contaminants, and even pathogens from water.

Carbon-based nanomaterials: Carbon-based nanomaterials such as graphene oxide, carbon nanotubes, and activated carbon nanoparticles are widely employed in water treatment processes. They possess excellent adsorption properties and can remove organic pollutants, dyes, and certain heavy metals from water.

Ceramic nanomaterials: Ceramic nanoparticles like zeolites, alumina, and clay minerals are used for water purification due to their ion exchange properties and large surface areas. They can effectively remove heavy metals, organic compounds, and inorganic contaminants from water.

Magnetic nanomaterials: Magnetic nanoparticles, typically based on iron oxide or other magnetic materials, can be functionalized with specific coatings to selectively remove contaminants from water. They can be easily separated from water using a magnetic field, making their recovery and reuse convenient.

Hybrid nanocomposites: Combinations of different nanomaterials are often utilized to develop hybrid nanocomposites for water treatment. These composites exploit the synergistic effects of multiple materials, enhancing the overall efficiency of pollutant removal. Common examples include metal-organic frameworks (MOFs) and nanocomposite membranes.

It is important to note that the selection of nanomaterials for water treatment depends on the specific pollutants present in the water, desired treatment goals, and the compatibility of materials with the environment. Additionally, thorough testing and evaluation of any nanomaterials used for water treatment must be conducted to ensure their safety and efficiency.