Capturing Contaminants, Producing Purity

Capturing Contaminants, Producing Purity

07:22 08 August in News

Water is critical to human life. We know this.

We know our bodies require water to survive. We know the composition of our brains and hearts are 73% water and our lungs, 83%. We know we should drink 2-3 liters of water per day, depending upon our gender. We know, intimately, that water is critical to survival, our survival. [1]

Unfortunately, water is not always pure. Everyday, millions of Americans drink contaminated water. Pollutants such as Lead, Copper, Arsenic, Nitrites, and Radionuclides slip into the sips of more than 42 million individuals a day. Day by day, drop by drop, death-dealing poisons seep into brains, hearts, and lungs. [2]

David McGlincheyEnter Latika Menon, Associate Professor of Physics at Northeastern University, and her titania nanotubes. Titania nanotubes are resistant to corrosion, are biologically and chemically inert —  they kill bacteria, attack organic pollutants, and separate water and oils. Titania nanotubes seem tailor made for water purification. But, titania nanotubes are naturally chaotic and disorganized, and, thus, inefficient. Yet, when Professor Menon’s pioneering fabrication method is employed, titania nanotubes become thinner, longer, and aligned; in other words, they become more efficient and effective.

Previous fabrication techniques produce titania nanotubes of 7 micrometers in length with diameters of 40 nanometers, while Menon’s technique can generate tubes up to 50 micrometers long with diameters of 20 nanometers — 7 times longer and twice as thin. Additionally, Menon’s method significantly eclipses the speed of other approaches. What used to take 24 hours now takes 80 seconds! Superior quality in seconds, literally. [3]

Swiftly fabricating superior titania nanotubes is only one step in addressing the problem of polluted water. The next requires engineering a scalable application, which Professor Menon has undertaken through her startup, Menon Laboratories, where filtration membranes harnessing the potency of titania nanotubes are currently being developed for industrial use.

The prototype developed by Menon Laboratories aims to treat “produced water” in an environmentally and economically sustainable way. Produced water is extremely contaminated subterranean water extracted alongside oil and gas. On average, 77 billion barrels of produced water (roughly 4.2 trillion gallons) are pumped annually from wells worldwide. [4] The 900,000+ wells in the US generate approximately 21 billion of these barrels. [5]

ИлонаМолчановаHistorically, these trillions of polluted gallons were poured into evaporation ponds; but, through heightened environmental concern, regulation has engendered new modes of treatment with varying degrees of environmental and economic success. One method involves re-injecting produced water back into wells while other methods seek to extract additional value via repurposing. In terms of cost, re-injection rates range from $.70 – 4.00 per barrel; treatment for oil and gas production use, $.04 – .07; and purification for consumption rates, $.025 – 2.00. [4]

Increasingly robust regulation has spurred innovation in produced water methods and filtration membranes are leading the way. Membranes have numerous advantages over conventional methods, one of which is a steep reduction in, or even elimination of, chemical pre-treatment of produced water. Other benefits include reduced energy, space, and replacement requirements. [4]

LauraOne drawback of membrane filtration, however, is “fouling.” Fouling occurs when heavy materials clog the flow of water through the membrane thereby increasing pressure within the system and backing it up. Once a membrane is fouled, time and energy are required to clean or replace it, which translates into increased cost. [6] Menon Lab’s filtration prototype has an advantage here since the pioneering design eliminates fouling while maintaining flow rates as high as 500 LMH for oil-water and 1000 LMH for deionized. [5]  

Purifying industrial wastewater matters significantly to those who live downstream; and, for those dwelling in arid environs, nearby wells can become a source of potable water — safe for irrigating, cooking, and drinking. 

Purer water, healthier bodies: both made possible by Menon’s extraordinary titania nanotubes.

By uniting research and entrepreneurship, Professor Latika Menon compounds the impact of innovation and brilliantly models Northeastern’s ethos of “use-inspired” research.

Addendum

The scope of titania nanotubes is not only limited to water filtration. Given their remarkable capacity to convert light into electricity, they are being called upon to accelerate solar energy harvesting — another crucial need that Menon’s exemplary nanotubes can address.


Sources

[1] “The Water in You.” U.S. Geological Survey

[2] “Threats on Tap: Widespread Violations Highlight need for Investment in Water Infrastructure and Protections.” Natural Resources Defense Council

[3] “Ultra-High Aspect Ratio Titania Nanotubes.” Advanced Materials

[4] “State of the Art Treatment for Produced Water”

[5] “One-Dimensional Nanomaterials for Energy and Electronics Applications”

[6] “Ceramic Membrane Filtration of Produced Water for Oil and Gas Operations”

Cover image by avanbeeck. All rights reserved.
Image 1 by Dave McGlinchey. All rights reserved.
Image 2 by ИлонаМолчанова. All rights reserved.
Image 3 by L*aura. All rights reserved.

Written by Brice Tennant