New magnetic nanoparticles to aid in water purification

Bhopal: Researchers at the Indian Institute of Science Education and Research Bhopal (IISER) have successfully produced porous magnetic nanoparticles, which can help in sustainable water desalination and purification.

The nanoparticles, which are minuscule particles approximately one hundred thousand times smaller than the width of a human hair, have been engineered for multiple applications such as heat and light-induced removal of salt from seawater, the extraction of potable water from wastewater contaminated with dyes and deicing and anti-icing processes.

It was produced using a simple method inspired by Indian earthen lamps. The process involved saturating cotton with nickel salt and mustard oil, and igniting it using a lighter, resulting in the formation of these specialised magnetic nanoparticles.

The synthesised magnetic nanoparticles was assessed for its photothermal activities for three purposes -- photothermal desalination of simulated seawater, photothermal separation of dye molecules from effluent and de-icing applications.

The study, published in the reputed peer-reviewed journal American Chemical Society - EST Engineering, also showed that the nanoparticles could completely remove dye molecules from water when exposed to light and heat. Furthermore, these nanoparticles absorb near-infrared radiation from their environment, leading to effective de-icing properties as they heat up.

“Porous magnetic carbon materials are excellent for photothermal applications because they interact with light waves in unique ways. The interaction is more effective with highly porous materials, as they offer additional pathways for waves to bounce around and be absorbed,” said Sankar Chakma, Assistant Professor, Department of Chemical Engineering, IISER Bhopal, in a statement on Monday.

“The photothermal desalination using our magnetic nanoparticles was effective with excellent water evaporation rate. This is because of improved mass transfer through a porous medium, like transpiration and capillary action, aiding faster upward movement of water molecules,” said Chakma, also the lead researcher.

One of the primary global challenges in the world is obtaining clean and usable freshwater from sources like wastewater and seawater. It is estimated that around two-third of the world’s population will soon live in regions with water scarcity issues. To address this, desalination, a process that can provide local water sources for about 40 per cent of coastal communities, is crucial.

Desalination methods that produce usable water from seawater typically involve processes that need a lot of heat, like distillation or membrane-based techniques like reverse osmosis. However, these methods often require expensive equipment, large setups, and substantial energy consumption. A more sustainable alternative is photothermal (light+heat) -- assisted desalination, which harnesses renewable solar energy. The creation of magnetic nanoparticles with diverse applications, from efficient desalination processes to dye removal and de-icing represents a significant step towards sustainable and accessible water resources. Such advancements in science offer hope for a future where clean and safe water is more readily available to communities worldwide.