A team of researchers from the CONICET, at the Centro de Tecnología de Recursos Minerales y Cerámica (CETMIC, CONICET-UNLP-CICPBA), developed a simple, cheap, and scalable method to remove arsenic and nitrates from water.
The advancement, published in the scientific journal Waste and Biomass Valorization, is based on the use of charcoal treated chemically and thermally, capable of reducing the concentration of these contaminants by more than 50%.
Drinking water and circular economy: two problems, one solution
The project not only aims to solve a critical problem of access to drinking water in vulnerable communities but also proposes an alternative to reuse industrial and urban waste.
Argentina annually produces large volumes of plant biomass —sunflower seed shells, pruning leaves and branches, among other by-products— that are often considered waste. However, this organic matter retains a high energy and chemical value that can be harnessed to produce charcoal, a material with great adsorption capacity for contaminants.
How the method to remove arsenic and nitrate from water works
The group led by researcher Pablo Arnal had already demonstrated the effectiveness of charcoal in removing cationic contaminants (positively charged ions, such as heavy metals or agrochemicals).
The new challenge was to prove whether, by modifying the surface of the charcoal, it could also capture anionic contaminants (negatively charged ions), such as arsenic and nitrates.
To achieve this, the researchers:
- Produced charcoal in a simple and economical chemical reactor, designed in 2021. The device, built with basic materials like tin cans and chimney tubes, allows for quick and low-cost charcoal production.
- Treated the surface of the charcoal with nitric acid and then subjected it to a thermal process at 800 °C, which rearranged the atoms and generated new chemical bonds.
- This treatment created surface anchoring points, capable of effectively fixing anionic contaminants and retaining them.
The result: a reduction of up to 55% in nitrate concentration in the tests conducted.
Social, scientific, and industrial impact
The advancement has multiple implications:
- Social impact: offers an accessible solution for communities with drinking water access issues, through filters with treated charcoal tablets applicable to tanks or cisterns.
- Scientific impact: opens new lines of research on the use of charcoal not only as a decontaminant but also in areas such as energy storage.
- Industrial impact: turns waste into valuable raw material, reducing disposal costs and generating opportunities within the framework of the circular economy.
“The method is profitable, simple, and effective. Additionally, it reuses industrial or urban waste, generating a positive environmental impact,” highlighted Arnal.
A step towards sustainability
The innovation from CONICET demonstrates how applied science can transform waste into solutions for critical problems like water contamination.
With larger-scale tests, this technology could become a key tool to improve the quality of life for thousands of people, while also promoting environmental sustainability and industrial competitiveness.
