June 2010, Vol. 22, No.6

Waterline

Super Sponge Soaks Up Oil, Not Water

Researchers at Case Western Reserve University (Cleveland) have created a super sponge. The lightweight sponge, an aerogel made of clay and high-grade plastic, soaks up oil — but not water — from contaminated water, according to a university news release.

The aerogel is made by mixing clay with a polymer and water. The mixture is freeze-dried, and air fills the gaps left by the loss of water, the news release says. The resulting material contains approximately 96% air, 2% polymer, and 2% clay. This particular oil-absorbing aerogel is one of several clay-based aerogels being made at the university.

The university granted a 9-month exclusive license for these clay-based aerogel technologies to AeroClay Inc. (Independence, Ohio), a startup company that will include David Schiraldi, chairman of the Macromolecular Science and Engineering Department at Case Western's Case School of Engineering, as chief scientific officer. Schiraldi said his laboratory has been working on the technology behind the aerogel sponge for more than 7 years.

“There are a range of polymers that can be used in this, and other, applications,” Schiraldi explained. Using different polymers produces materials with different properties, according to the news release. More than 30 different polymers have been included in aerogel materials. They are all low-density products that can be used as insulation, absorbants, and structural mates, Schiraldi explained.

Chemically, the polymer used in this aerogel loves oil and hates water, Schiraldi said. The result is that this aerogel does not absorb any water. That property “differentiates it from other absorbants, which get soggy in water,” Schiraldi added.

Laboratory tests show that if the oil is uncontaminated in the water, it can be squeezed back out of the aerogel sponge and reused, the news release says. Researchers believe this technology will clean up oil and solvent spills on factory floors, as well as on roadways and in rivers and oceans.

The aerogel can be produced in grains, sheets, or blocks of almost any shape. It’s equally effective in fresh water and saltwater, and on hard surfaces, the release says. Because absorption is a physical phenomenon, there is no chemical reaction between the material and oil. 

U.S. EPA Announces National Water Program Research Strategy

The U.S. Environmental Protection Agency (EPA) National Water Program published its first strategy identifying the research needed achieve its goals, meet statutory obligations, and fulfill court mandates. The strategy defines research needed to address EPA’s strategic goals and objectives for clean and safe water, according to the strategy’s Web site.

The strategy identifies the four priority themes of healthy watersheds and coastal waters, safe drinking water, sustainable water infrastructure, and water security. Within each theme, research needs are categorized into the areas of aquatic health effects, human health effects, occurrence and exposure, methods development, and treatment technologies and effectiveness. Through this strategy, EPA aims to ensure that research, science, and technology needs are identified in a comprehensive plan; research partnerships and collaborations are expanded; and private and international research communities are engaged in investigating water research needs, the Web page says. For more information, see www.epa.gov/waterscience/strategy.

SWAT Put to the Test

A recent test of the U.S. Agricultural Research Service (ARS) Soil and Water Assessment Tool (SWAT) showed that the model accurately estimates pollutant levels in a watershed on an annual basis. ARS researchers tested SWAT on the Warner Creek watershed in Frederick County, Md., during an 11-year study, according to an ARS news release.

SWAT, developed by a team of ARS agricultural engineers in the early 1990s, is a model that encompass entire river basins. It was developed to quantify the impact of land management practices in large, complex watersheds.

Water resources engineer Aisha Sexton and soil scientist Ali Sadeghi at the ARS Hydrology and Remote Sensing Laboratory in Beltsville, Md., worked on the study with Adel Shirmohammadi, a watershed hydrologic and water quality modeler and professor at the University of Maryland, College Park. Shirmohammadi and Hubert Montas, an associate professor in bioenvironmental and water resources engineering at the university, had several graduate students and post-doctoral researchers assist with the project. The U.S. Environmental Protection Agency (EPA) provided major funding, and ARS provided supplemental funding for the project, the news release says.

The Warner Creek watershed, a mix of farm, forest, and urban land area, is approximately 2.6 km2 (1 mi2) and drains into a tributary of the Monocacy River Basin. High levels of nitrogen and phosphorus, primarily from cattle manure and crop fertilizers, travel through the 2580-km2 (996-mi2) Monocacy River Basin that flows into Chesapeake Bay.

The researchers found the SWAT model to be satisfactory for use on an annual basis in mixed land-use watersheds in the Piedmont physiographic region studied and, therefore, suitable for use in EPA’s Total Maximum Daily Load program, the news release says.

 

©2010 Water Environment Federation. All rights reserved.