Water is one of the essential enablers of life on earth. But pure water is not available to a large fraction of the population of the planet. While availability is an issue, contamination is another major concern which threatens the survival of many. Intensive farming, rapid industrialization and increasingly sophisticated lifestyles have added artificial chemicals into the water bodies.
While pesticide residues in ground waters were unexpected years ago as soil was thought to act as a filter, it is an established fact that even drinking water is contaminated with them in many parts of the world. Pesticide residues measured in drinking water and soft drinks in India far exceed the acceptable limits.
Researchers at India’s Institute of Technology Madras in Chennai, India, developed a purification device that filters water through a specially crafted mixture of nanoparticles to remove harmful contaminants.
Their study was published in the journal Proceedings of the National Academy of Sciences.
The system they have developed is a two-stage filtration process that provides 10 liters of clean water in just an hour’s time. The biggest challenge, the team says, was figuring out how to deliver silver ions into the water to be processed, without using any electricity. The process also had to use a minimal amount of silver ions to meet international safety standards. The answer, they say, was to use a new material that employs silver nanoparticles that are trapped in tiny cage-like structures made of other clay materials.
Other nanoparticles are used to create other materials that serve as filters, killing microbes and sucking heavy metals out of the water, making it safe to drink or use for cooking. The first stage of the process kills viruses, bacteria and other dangerous micro-biota. The second stage absorbs heavy metals such as lead and arsenic.
The result is an extremely inexpensive portable water purification device—the system cost is comparable to other portable filtration systems, but the processing itself comes to less than $3 per year. The filters are good for approximately one year (3,600 liters) and filtration can be run more than once per day if needed. The researchers believe their device is capable of providing all the drinking water a family of four would need.
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