Image Courtesy of Wikimedia.
Access to clean drinking water may feel like a given in the United States, but a variety of contaminants lurk beneath the surface of our water sources. In particular, when present in water sources at high levels, nitrates—compounds commonly found in fertilizer, sewage, and manure—are often associated with birth defects and death of aquatic life. The US Environmental Protection Agency (EPA) sets the nitrate limit at ten milligrams per liter, yet the metal catalysts currently used to remove nitrate can cause another form of contamination when dissolved in water.
A research team led by postdoctoral associate Yingzheng Fan from the Winter Lab at Yale investigated a new nitrate cleaning system: nanoporous electrified membranes containing carbon nanotubes (CNT-EMs). These CNT-EMs are composed of interlaid stacks of carbon nanotubes arranged in cylindrical shapes, creating tiny gaps known as nanopores. The team discovered that these membranes were not only more efficient than the current alternatives but also demonstrated greater long-term stability. With a filtration time of fifteen seconds, they achieved eighty percent nitrate conversion.
What makes this research even more fascinating is its relevance to Yale and New Haven itself. The water tested in the paper was gathered from Lake Wintergreen, located less than five miles away from Yale’s campus. “I want to incorporate this membrane into large-scale filtration setups and hopefully try different locations,” Fan said. Although CNT-EMs are still in their early stages of development, the initial results are promising. More importantly, this research reveals the complex work behind ensuring access to something many take for granted—clean drinking water.