IIT Madras Researchers show that Natural Minerals are broken by Water Droplets to form Nanoparticles

Researchers from the Indian Institute of Technology Madras (IIT Madras) have discovered that common minerals can be broken down into nanoparticles by water microdroplets. This groundbreaking research is the first from IIT Madras to be published in the prestigious journal ‘Science’.

Atmospheric water droplets, including clouds and fog, can become charged through ionic species and contact electrification. When these charged microdroplets interact with minerals, they disintegrate, creating nascent surfaces where various catalytic processes can occur, potentially forming new molecules. These processes could play a crucial role in the origin of life.

The researchers suggest that 'microdroplet showers' containing nanoparticles and molecules falling to Earth may significantly influence the chemical and biological evolution of the planet.

‘Science’ is the peer-reviewed academic journal of the American Association for the Advancement of Science, the world’s oldest and largest general science organization. Since its founding in 1880 with seed money from inventor Thomas Edison, the journal has been at the forefront of important scientific discoveries and is considered one of the world’s top academic journals, with articles frequently ranking among the most cited globally.

The research was led by Prof. Thalappil Pradeep of the Chemistry Department at IIT Madras, a Padma Shri awardee, and Ms. B. K. Spoorthi, the first author of the research paper, who recently completed her PhD at IIT Madras.

The computational work for the research was conducted by Ms. Koyendrila Debnath under the guidance of Prof. Umesh V. Waghmare from the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bengaluru, and President of the Indian Academy of Sciences. The findings were published in the 31st May 2024 issue of ‘Science’ (DOI: 10.1126/science.adl3364).

Highlighting the significance of this research, Prof. Thalappil Pradeep stated, “Microdroplets are known to enhance chemical reactions, leading to the formation of new chemical bonds. We hypothesized that microdroplets could also break chemical bonds, which led to this discovery.”

Discussing the future steps, Prof. Pradeep added, “If this process occurs naturally, it could significantly transform rocks into natural nanoparticles, which are essential components of soil. Essentially, we

have found a method to convert sand into soil. With adequate resources, this discovery could potentially help deserts flourish.”

Elaborating on the applications of this research, Ms. B. K. Spoorthi, the first author of the paper, said, “This finding presents a revolutionary technique for soil formation, dramatically accelerating natural weathering processes from centuries to moments. Beyond environmental benefits, this method advances nanotechnology and materials science, providing a sustainable and efficient means for nanoparticle production with broad industrial applications.”

In their experiments, the researchers observed that hard minerals such as river sand, ruby, and alumina, when incorporated into tiny charged water droplets, broke down spontaneously into nanoparticles within milliseconds. The formed nanoparticles were then collected and characterized using advanced methods. Computer simulations suggested that the phenomenon might occur through a process called ‘proton-induced slip,’ where atomic layers in the minerals slip between each other, assisted by protons. Protons and other reactive species are known to exist in tiny water droplets.

Speaking about the mechanism, Prof. Umesh V. Waghmare explained, “The phenomenon involves complex processes inherent to water microdroplets. Understanding its mechanism will stimulate many fundamental scientific studies."

This rapid weathering process could be significant for soil formation, given the prevalence of charged aerosols in the atmosphere. Normally, soil formation through rock weathering involves multiple factors and takes 200-400 years to yield one centimeter of soil, composed of various particle sizes. Nanoparticles of minerals like silica are crucial for the growth of crops such as rice and wheat.