Tag Archives: water treatment

Removing titanium dioxide nanoparticles from water may not be that easy

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A March 10, 2015 news item on Nanowerk highlights some research into the removal of nanoscale titanium dioxide particles from water supplies (Note: A link has been removed),

The increased use of engineered nanoparticles (ENMs) in commercial and industrial applications is raising concern over the environmental and health effects of nanoparticles released into the water supply. A timely study that analyzes the ability of typical water pretreatment methods to remove titanium dioxide, the most commonly used ENM, is published in Environmental Engineering Science (“Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry”). The article is available free on the Environmental Engineering Science website until April 10, 2015.

A March 10, 2015 Mary Ann Liebert, Inc., publishers news release (also on EurekAlert), which originated the news item, provides more details about the work (Note: A link has been removed),

Nichola Kinsinger, Ryan Honda, Valerie Keene, and Sharon Walker, University of California, Riverside, suggest that current methods of water prefiltration treatment cannot adequately remove titanium dioxide ENMs. They describe the results of scaled-down tests to evaluate the effectiveness of three traditional methods—coagulation, flocculation, and sedimentation—in the article “Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry.”

“As nanoscience and engineering allow us to develop new exciting products, we must be ever mindful of associated consequences of these advances,” says Domenico Grasso, PhD, PE, DEE, Editor-in-Chief of Environmental Engineering Science and Provost, University of Delaware. “Professor Walker and her team have presented an excellent report raising concerns that some engineered nanomaterials may find their ways into our water supplies.”

“While further optimization of such treatment processes may allow for improved removal efficiencies, this study illustrates the challenges that we must be prepared to face with the emergence of new engineered nanomaterials,” says Sharon Walker, PhD, Professor of Chemical and Environmental Engineering, University of California, Riverside.

Here’s a link to and a citation for the paper,

Titanium Dioxide Nanoparticle Removal in Primary Prefiltration Stages of Water Treatment: Role of Coating, Natural Organic Matter, Source Water, and Solution Chemistry by Nichola Kinsinger, Ryan Honda, Valerie Keene, and Sharon L. Walker. Environmental Engineering Science. doi:10.1089/ees.2014.0288.

This paper is freely available until April 10, 2015.

Interestingly Sharon Walker and Nichola Kinsinger recently co-authored a paper (mentioned in my March 9, 2015 post) about copper nanoparticles and water treatment which concluded this about copper nanoparticles in water supplies,

The researchers found that the copper nanoparticles, when studied outside the septic tank, impacted zebrafish embryo hatching rates at concentrations as low as 0.5 parts per million. However, when the copper nanoparticles were released into the replica septic tank, which included liquids that simulated human digested food and household wastewater, they were not bioavailable and didn’t impact hatching rates.

Taking these these two paper into account (and the many others I’ve read), there is no simple or universal answer to the question of whether or not ENPs or ENMs are going to pose environmental problems.

Removing pollutants from water with nano-brushes

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The Jan. 16, 2012 news item ( by Jim Hannah) on Nanowerk about nano-brushes and water pollution reminded of an MIT (Massachusetts Institute of Technology) event at the last Venice Biennale, which featured a demonstration of nanotechnology-enabled oil-absorbing robots (my Aug. 26 2010 posting includes a video of the MIT project, Seaswarm).

Here’s an overview of the situation, from the news item,

The need to efficiently purify water is mushrooming into a massive global issue as human and industrial consumption of water grows.

The United Nations estimates that about 1.1 billion people currently lack access to safe water. Several forecasts suggest that freshwater may become the “oil” of the 21st century – expensive, scarce and the cause of geo-political conflicts.

In the United States, aging water-treatment infrastructure is struggling to keep up with growing threats to the clean-water supply, making water purification a major energy expense. Technologies like the “nano-brush” may provide some relief.

Dr. Sharmila Mukhopadhyay of Wright State University (Ohio, US) is working on the problem with her research team and they are developing (from the news item),

… near molecular-sized “nano-brushes.”

These fuzzy structures have bristles made up of thousands of tiny, jellyfish-like strands. The increased surface area of the bristles, with proper coatings, allows them to behave like powerful cleaners that kill bacteria and destroy contaminants that pollute water.

Here’s a brief description of how this would work,

Different materials can be broken down into nano-particles and then attached to the bristles of the brushes.

For example, particles of silver kill bacteria on contact without being dispersed as pollutants in the water. Particles of palladium break up carbon-tetrachloride and other water pollutants. And particles of titanium oxide can zap pollutants when activated by sunlight.

Mukhopadhyay plans to attach three or four different kinds of water-purifying particles to the nano-brushes. “So simultaneously you can combine multiple environmental cleanup applications into one single component,” she said.

They have been testing this solution in the lab and they appear to be confident that it will be deployed in the field in the next few years. I’m thrilled that the nanoparticles being used for the cleanup don’t become pollutants themselves (at least, not so far).

Flies carry nanoparticles; EPA invites comments; scientific collaboration in virtual worlds

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A new study is suggesting that flies exposed to nanoparticles in manufacturing areas or other places with heavy concentrations could accumulate the particles on their bodies and transport them elsewhere. From the media release on Nanowerk News,

During the experiments, the researchers noted that contaminated flies transferred nanoparticles to other flies, and realized that such transfer could also occur between flies and humans in the future. The transfer involved very low levels of nanoparticles, which did not have adverse effects on the fruit flies.

It makes perfect sense when you think about it. Flies pick up and transport all manner of entities so why wouldn’t they pick up nanoparticles in their vicinity?

In other news, the US Environmental Protection Agency (EPA) has asked for comments on case studies of nanoscale titanium dioxide in water treatment and sunscreens. Presumably you have to be a US citizen to participate. For more information on the call for comments, check out this item on Nanowerk News. From the item,

EPA is announcing a 45-day public comment period for the draft document, Nanomaterial Case Studies: Nanoscale Titanium Dioxide in Water Treatment and Topical Sunscreen (External Review Draft), as announced in the July 31, 2009 Federal Register Notice. The deadline for comments is September 14, 2009.

Yesterday, I came across an announcement about scientific collaboration in a virtual world (specifically Second Life). It’s the first professional scientific organization, Meta Institute for Computational Astrophysics (MICA), based entirely in a virtual world.

This idea contrasts somewhat with the NanoLands concept from the National Physical Laboratory in the UK where an organization with a physical location creates a virtual location. (You can see my interview with Troy McConaghy, part of the original NanoLands design team, here.)  The project blog seems to have been newly revived and you can find out more about NanoLands and their latest machinima movies. (If you want to see the machinima, you need a Second Life account.)

What I found particularly interesting about MICA is this bit from their media release on Physorg.com,

In addition to getting people together in a free and convenient way, virtual worlds can offer new possibilities for scientific visualization or “visual analytics.” As data sets become larger and more complex, visualization can help researchers better understand different phenomena. Virtual worlds not only offer visualization, but also enable researchers to become immersed in data and simulations, which may help scientists think differently about data and patterns. Multi-dimensional data visualization can provide further advantages for certain types of data. The researchers found that they can encode data in spaces with up to 12 dimensions, although they run into the challenge of getting the human mind to easily grasp the encoded content.

Shades of multimodal discourse! More tomorrow.