At the droplet of a hat: Capturing mixable liquid interaction

When raindrops fall into bodies of water, milk is added to a cup of coffee, and in other mixing and rinsing processes, you might wonder how one liquid is absorbed by the other. Small droplets can be absorbed so fast that our minds perceive it to be instantaneous. However, in reality, there is much more to the process than first meets the eye.

In collaboration with Daniel Walls and Prof. Gerald Fuller from Stanford University, Dr. Simon Haward and Prof. Amy Shen from the Okinawa Institute of Science and Technology Graduate University (OIST) were able to, for the first time, capture the spreading of a droplet as it was immersed in a second mixable, or miscible, liquid. The results could have a far-reaching impact into general mixing, dilution, rinsing and washing processes, including how oil from oil spills mix with animal body oil. The paper describing these results has recently been published in Physical Review Fluids.

“There is always a clear interface between liquids that don’t mix, say oil and water. For example, in salad dressing you can clearly see the droplets,” Shen, co-author and head of OIST’s Micro/Bio/Nanofluidics Unit said. “But when you have two miscible liquids, like water and vinegar, they will integrate with each other rapidly and that process is pretty difficult to study because the interface is much less clear.”

In order to observe the interactions of multiple different pairs of miscible liquids, the team created a device that allowed a droplet on a glass slide to be slowly submerged into another liquid held below in a transparent cube. High speed cameras were set up around the device to document the way the drop spreads and then integrates into the second liquid. From the images, the team could see that the droplets spread in a way that made them look like little hats, with the brim continuing to spread over time until the droplet was fully integrated into the second liquid.

To further explore what happens in the liquid to create these droplet hats, the team added particles to the liquid and illuminated the particles with a laser. In this way, they could understand more about what was happening inside the fluid and why the droplet begins to look like a hat.

“We could see the motion of the fluid inside the droplets as the droplets spread out on the surface,” Haward, co-author and group leader of OIST’s Micro/Bio/Nanofluidics Unit said. “This made it very clear that the flow slides down around the top edges and the sides of the droplet, while the fluid in the center does not move.”

“There is a qualitative difference in how the shape of liquid evolves when you have two miscible liquids instead of two immiscible liquids,” Walls, Ph.D. student at Stanford University said. “And this is the first time that the spreading of miscible liquids has been captured in this way.”

Haward added, “There are numerous potential applications. Understanding the spread of miscible liquids can be useful in many different fields.”

Story Source:

The above post is reprinted from materials provided by Okinawa Institute of Science and Technology (OIST) Graduate University. Note: Materials may be edited for content and length.

Researchers discover a new method to boost oil recovery

As oil producers struggle to adapt to lower prices, getting as much oil as possible out of every well has become even more important, despite concerns from nearby residents that some chemicals used to boost production may pollute underground water resources.

Researchers from the University of Houston have reported the discovery of a nanotechnology-based solution that could address both issues — achieving 15 percent tertiary oil recovery at low cost, without the large volume of chemicals used in most commercial fluids.

The solution — graphene-based Janus amphiphilic nanosheets — is effective at a concentration of just 0.01 percent, meeting or exceeding the performance of both conventional and other nanotechnology-based fluids, said Zhifeng Ren, MD Anderson Chair professor of physics. Janus nanoparticles have at least two physical properties, allowing different chemical reactions on the same particle.

The low concentration and the high efficiency in boosting tertiary oil recovery make the nanofluid both more environmentally friendly and less expensive than options now on the market, said Ren, who also is a principal investigator at the Texas Center for Superconductivity at UH. He is lead author on a paper describing the work, published June 27 in the Proceedings of the National Academy of Sciences.

“Our results provide a novel nanofluid flooding method for tertiary oil recovery that is comparable to the sophisticated chemical methods,” they wrote. “We anticipate that this work will bring simple nanofluid flooding at low concentration to the stage of oilfield practice, which could result in oil being recovered in a more environmentally friendly and cost-effective manner.”

In addition to Ren, researchers involved with the project include Ching-Wu “Paul” Chu, chief scientist at the Texas Center for Superconductivity at UH; graduate students Dan Luo and Yuan Liu; researchers Feng Wang and Feng Cao; Richard C. Willson, professor of chemical and biomolecular engineering; and Jingyi Zhu, Xiaogang Li and Zhaozhong Yang, all of Southwest Petroleum University in Chengdu, China.

The U.S. Department of Energy estimates as much as 75 percent of recoverable reserves may be left after producers capture hydrocarbons that naturally rise to the surface or are pumped out mechanically, followed by a secondary recovery process using water or gas injection.

Traditional “tertiary” recovery involves injecting a chemical mix into the well and can recover between 10 percent and 20 percent, according to the authors.

But the large volume of chemicals used in tertiary oil recovery has raised concerns about potential environmental damage.

“Obviously simple nanofluid flooding (containing only nanoparticles) at low concentration (0.01 wt% or less) shows the greatest potential from the environmental and economic perspective,” the researchers wrote.

Previously developed simple nanofluids recover less than 5 percent of the oil when used at a 0.01 percent concentration, they reported. That leaves oil producers forced to choose between a higher nanoparticle concentration — adding to the cost — or mixing with polymers or surfactants.

In contrast, they describe recovering 15.2 percent of the oil using their new and simple nanofluid at that concentration — comparable to chemical methods and about three times more efficient than other nanofluids.

Dan Luo, a UH graduate student and first author on the paper, said when the graphene-based fluid meets with the brine/oil mixture in the reservoir, the nanosheets in the fluid spontaneously go to the interface, reducing interfacial tension and helping the oil flow toward the production well.

Ren said the solution works in a completely new way.

“When it is injected, the solution helps detach the oil from the rock surface,” he said. Under certain hydrodynamic conditions, the graphene-based fluid forms a strong elastic and recoverable film at the oil and water interface, instead of forming an emulsion, he said.

Researchers said the difference is due to the asymmetric property of the 2-dimensional material. Nanoparticles are usually either hydrophobic — water-repelling, like oil — or hydrophilic, water-like, said Feng Wang, a post-doctoral researcher who shared first author-duties with Luo.

“Ours is both,” he said. “Ours is Janus and also strictly amphiphilic.”

Story Source:

The above post is reprinted from materials provided by University of Houston. The original item was written by Jeannie Kever. Note: Materials may be edited for content and length.

Water windfall' discovered beneath California's Central Valley

California’s drought-stricken Central Valley harbors three times more groundwater than previously estimated, Stanford scientists have found. Accessing this water in an economically feasible way and safeguarding it from possible contamination from oil and gas activities, however, will be challenging.

“It’s not often that you find a ‘water windfall,’ but we just did,” said study co-author Robert Jackson, the Michelle and Kevin Douglas Provostial Professor at Stanford. “There’s far more fresh water and usable water than we expected.”

The research, published in the journal Proceedings of the National Academy of Sciences the week of June 27, highlights the need to better characterize and protect deep groundwater aquifers not only in California but in other parched regions as well.

“Our findings are relevant to a lot of other places where there are water shortages, including Texas, China and Australia,” said study co-author Mary Kang, a postdoctoral associate at Stanford School of Earth, Energy & Environmental Sciences.

A fresh look at groundwater

Previous estimates of groundwater in California are based on data that are decades old and only extend to a maximum depth of 1,000 feet, and often less. Until now, little was known about the amount and quality of water in deeper aquifers.

“Water a thousand feet down used to be too expensive to use,” said Jackson, who is also a senior fellow at Stanford Woods Institute for the Environment and at the Precourt Institute for Energy. “Today it’s used widely. We need to protect all of our good quality water.”

Times are different now. California is in the midst of its fifth year of severe drought, and in 2014 Gov. Jerry Brown declared a drought emergency in the state. To meet its surface water needs, the state is increasingly turning to groundwater supplies.

In the new study, Jackson and Kang used data from 938 oil and gas pools and more than 35,000 oil and gas wells to characterize both shallow and deep groundwater sources in eight California counties.

The researchers concluded that when deeper sources of groundwater are factored in, the amount of usable groundwater in the Central Valley increases to 2,700 cubic kilometers — or almost triple the state’s current estimates.

Complications to consider

While this is good news for California, the findings also raise some concerns. First, much of the water is 1,000 to 3,000 feet underground, so pumping it will be more expensive. Without proper studies, tapping these deeper aquifers might also exacerbate the ground subsidence — the gradual sinking of the land — that is already happening throughout the Central Valley. Groundwater pumping from shallow aquifers has already caused some regions to drop by tens of feet.

Furthermore, some of the deep aquifer water is also brinier — higher in salt concentration — than shallower water, so desalination or other treatment will be required before it can be used for agriculture or for drinking.

Another concern the Stanford scientists uncovered is that oil and gas drilling activities are occurring directly into as much as 30 percent of the sites where the deep groundwater resources are located. For example, in Kern County, where the core of California’s oil and gas industry is centered near the city of Bakersfield, one in every six cases of oil and gas activities was occurring directly into freshwater aquifers. For useable water — water that the U.S. Environmental Protection Agency deems drinkable if treated — the number was one in three.

Jackson and Kang stress that just because a company has hydraulically fractured or used some other chemical treatment near an aquifer doesn’t mean that the water is ruined.

“What we are saying is that no one is monitoring deep aquifers. No one’s following them through time to see how and if the water quality is changing,” Kang said. “We might need to use this water in a decade, so it’s definitely worth protecting.”

Story Source:

The above post is reprinted from materials provided by Stanford’s School of Earth, Energy & Environmental Sciences. The original item was written by Ker Than. Note: Materials may be edited for content and length.


News Releases from Region 03


Contact Information: 

WASHINGTON (June 23, 2016)  The U.S. Environmental Protection Agency and the Department of Justice today announced that D. G. Yuengling and Son Inc., has settled Clean Water Act (CWA) violations involving its two large-scale breweries near Pottsville, Pennsylvania.

In a consent decree filed today in federal court in Harrisburg, Pennsylvania, the company has agreed to spend approximately $7 million to improve environmental measures at its brewery operations after it allegedly discharged pollutants into the Greater Pottsville Area Sewer Authority municipal wastewater treatment plant.  Yuengling will also pay a $2.8 million penalty.

In addition, the consent decree includes a requirement to implement an environmental management system (EMS) focused on achieving CWA compliance at the facilities. Yuengling must hire a third party consultant to develop the EMS and a third party auditor to ensure proper implementation at the facility operations.

The company allegedly violated Clean Water Act requirements for companies that discharge industrial waste to municipal publically-owned wastewater treatment facilities numerous times between 2008 and 2015.  Companies must obtain and comply with permit limits on discharges of industrial waste that goes to public treatment facilities, which in many cases require “pretreatment” of waste before it is discharged.  The case was referred to EPA by the Greater Pottsville Area Sewer Authority (GPASA).

“Yuengling is responsible for serious violations of its Clean Water Act pretreatment discharge limits, posing a potential risk to the Schuylkill River which provides drinking water to 1.5 million people,” said EPA Regional Administrator Shawn M. Garvin.  “This history of violations and failure to fully respond to orders from the Greater Pottsville Area Sewer Authority and EPA to correct the problems resulted in this enforcement action.”

“It is vital that companies using municipal wastewater treatment facilities strictly follow pretreatment guidelines and permit limits for their wastewater.  It is what good neighbors expect, and it is what the law requires,” said Assistant Attorney General John C. Cruden for the Department of Justice’s Environment and Natural Resources Division.  “This settlement  requires Yuengling to put into place an environmental management system designed to manage compliance with the Clean Water Act in a systemic, planned, and documented manner to establish a top-down, prevention-focused approach. The settlement also mandates independent audits of Yuengling’s compliance with the consent decree, among other requirements.”

In a complaint filed concurrently with the settlement, the United States alleged that Yuengling violated pretreatment permit requirements, including discharge limits for biological oxygen demand (BOD), phosphorus, zinc and pH to the GPASA treatment plant, at least 141 times from 2008 to 2015.

Pretreatment helps remove or change the composition of pollutants in wastewater.  Unpermitted or excessive industrial discharges may interfere with the operation of public wastewater treatment plants, which are generally designed to handle sewage and domestic waste, leading to the discharge of untreated or inadequately treated wastewater into local waters.

In addition to the monetary penalty, Yuengling has also agreed to take measures that will prevent future violations including:

  • Designing and implementing an environmental management system for both breweries to ensure compliance with environmental laws;

  • Conducting a series of environmental audits and inspections to ensure ongoing environmental compliance;

  • Constructing a comprehensive pretreatment system at the Old Brewery;

  • Optimizing and improving operation and maintenance of the pretreatment system at the New Brewery;

  • Developing and implementing a communication and notification plan to quickly notify GPASA of any changes to the brewery facilites’ wastewater that may impact the public treatment facility;

  • Hiring two certified wastewater treatment operators; and implementing a process to identify, investigate and respond to any future CWA violations quickly and efficiently.

    The consent decree, which is subject to a 30-day public comment period and final court approval, is available at:

Filtered water deemed safe for everyone in the Flint community

News Releases from Region 05

Interagency testing shows filters are effective in removing high levels of lead in Flint water


Contact Information: 

FLINT, MI – The U.S. Environmental Protection Agency (EPA), in coordination with the U.S. Centers for Disease Control (CDC) , completed testing of water filters in Flint and found that the filters distributed by the State of Michigan effectively remove lead or reduce it to levels well below EPA’s action level of 15 parts per billion (ppb).

Over the past 2 months, EPA, at the request of CDC, collected additional samples at nearly 50 locations considered to be at high-risk for lead contaminated water–locations with full lead service lines, galvanized plumbing, and where the most vulnerable populations live, including pregnant mothers and children. The results provide strong reassurance of previous findings of the effectiveness of filters in removing lead. Nearly all filtered water came back at concentrations well below 1 ppb. The results of this effort are almost identical to a previous assessment in which EPA sampled close to 300 homes.

Based on EPA’s findings and previous independent filter testing by Virginia Tech University researchers and NSF International which certifies water filters, all local, state and federal agencies involved in the Flint crisis response agree that the use of these NSF verified filters makes water safe from lead for all populations. Pregnant and nursing women and children no longer need to drink bottled water to avoid lead exposure as long as they drink water that has passed through a filter rated to remove lead from drinking water.

“These findings reaffirm the effectiveness of filters at removing or reducing lead. This is an important step forward for providing a stable water system for the City of Flint,” said Tom Burke, EPA Science Advisor and Deputy Assistant Administrator for EPA’s Office of Research and Development. “Residents can be confident that EPA’s sampling results correspond with previous tests and are consistent with outside experts’ findings.”

“With the results of this testing, residents can be confident that they can use filtered water and protect their developing fetus or young child from lead,” said HHS Assistant Secretary for Preparedness and Response Dr. Nicole Lurie, who has led federal support efforts for the Flint crisis response. “It’s crucial that people in Flint install filters on faucets they use for drinking water, cooking, or brushing their teeth, and replace the filter cartridges regularly.”

The State of Michigan began making filters available in Flint for free in January 2016 and to date, FEMA has provided the state with more than 50,000 filters and over 243,000 filter replacement cartridges.

In late January, water samples taken by EPA, the Michigan Department of Environment Quality, and Virginia Tech researchers showed lead levels in some Flint homes exceeded 150 ppb. The companies that produce the filters had conducted testing to rate the filters up to 150 ppb, 10 times the EPA action level. Although previous Virginia Tech research had found the filters effective in removing lead at much higher levels, out of an abundance of caution, state and federal health agencies recommended that young children and pregnant women use bottled water to reduce the likelihood of lead exposure in babies and children under age 6.  

This announcement makes the use of water filters in Flint even more important than before. To assist with installation of filters and replacement cartridges for everyone in Flint, Michigan Works! intends to begin recruiting local residents to be trained as Filter Education Liaisons as part of a grant from the U.S. Department of Labor. This work will play a critical role in ensuring Flint residents are aware of the safeguards that will protect against lead-contaminated water and in assuring that everyone who needs help can access it.  Although this is positive news, agencies at all levels of government recognize that additional work is needed. The city, state, and federal governments are committed to working together to meet the overall goal of building a lasting, sustainable water system, one that has the capacity to provide clean drinking water to all residents.  

In the coming weeks, information on the Filter Education Liaison position will be posted to the Hot Jobs section of You can also learn more by stopping by Employment Services at GST Michigan Works! at 711 N. Saginaw Street, Flint.

To read the filter report, visit

For more information on EPA’s role in the Flint Drinking Water Response, visit