NSF and Stony Brook University: New nanotechnology to produce sustainable, clean water for developing nations

This technology would enable communities to produce their own water filters using biomass nanofibers, making clean water more accessible and affordable – Follow the Link below to Watch the Video.

The world’s population is projected to increase by 2-3 billion over the next 40 years. Already, more than three quarters of a billion people lack access to clean drinking water and 85 percent live in the driest areas of the planet.

Those statistics are inspiring chemist Ben Hsiao and his team at Stony Brook University. With support from the National Science Foundation (NSF), the team is hard at work designing nanometer-scale water filters that could soon make clean drinking water available and affordable for even the poorest of the poor.

Traditional water filters are made of polymer membranes with tiny pores to filter out bacteria and viruses. Hsiao’s filters are made of fibers that are all tangled up, and the pores are the natural gaps between the strands. The team’s first success at making the new nanofilters uses a technique called electrospinning to produce nanofibers under an electrical field.

Hsiao’s team is also looking to cut costs even further by using “biomass” nanofibers extracted from trees, grasses, shrubs — even old paper. Hsiao says it will be a few years yet before the environmentally friendly biomass filters are ready for widespread use in developing countries, but the filters will eliminate the need to build polymer plants in developing areas. Ultimately, those filters could be produced locally with native biomass or biowaste.

The research in this episode was supported by NSF award #1019370, Breakthrough Concepts on Nanofibrous Membranes with Directed Water Channels for Energy-Saving Water Purification.Silver Nano P clean-drinking-water-india

Watch the Video Here: New Nanotechnology for Sustainable, Clean Water for Developing Nations


MIT: Filtering Drinking Water with Nanofibers: Video

Published on Apr 21, 2016

Liquidity, an Alameda, California-based startup, has developed a low-cost water filter made from nanofibers that it hopes will reduce water-borne diseases in poor countries. A version designed for the developed world, Naked Filter, attaches to a plastic water bottle. Its membrane of electrospun nanofibers allows water to pass through it quickly.

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Stanford University: Nanowire-Coated Cotton Cleans Water by Zapping Bacteria to Death: Application: Cheap, Abundant Material, Low-Voltage Nano-Water-Filter

nanofilt_wires_newsIllness-inducing bacteria, meet nano-engineered cotton–and a quick death. Researchers have created a new “filter” that zaps bacteria with electric fields to clean drinking water. They say their system may find use in developing countries since it requires only a small amount of voltage (a couple of car batteries, a stationary bike, or a solar panel could do the job) and cleans water an estimated 80,000 times faster than traditional devices.

Instead of trapping bacteria in small pores like many slow-going traditional filters, the cotton and silver nanowire combo uses small electric currents running through the nanowires to kill the bacteria outright. In a paper to appear in the journal Nano Letters researchers say that 20 volts and 2.5 inches worth of the material killed 98 percent of Escherichia coli in the water they tested in their lab setup.

The authors argue that the filter’s silver nanowires and carbon nanotubes are cheap; the small amount of silver required makes its expense “negligible,” coauthor Yi Cui says in a press release, and the group chose to use cotton because of its abundance.

They needed a foundation material that was “cheap, widely available and chemically and mechanically robust.” So they went with ordinary woven cotton fabric. “We got it at Wal-mart,” Cui said. [Stanford University]

They made the potent combination by dipping the cotton first in a “broth” containing carbon nanotubes and then the silver nanowires, allowing the structures to coat the cotton fibers. The scanning electron microscope image above shows the silver nanowires compared to the large cotton fibers (the red line is 10 microns long). The current running though the material, a few milliamperes, may be fatal for the bacteria but it would barely makes a human tingle.

[B]ecause the voltage is so low, it doesn’t require serious electricity generation. A person could generate the power from a stationary bike or a hand-cranked device. No pumping is required either. The force of gravity is enough to allow the water and its nasties to pass through the cotton and get zapped! [Discovery News]

Next, the group hopes to test the device on other microorganisms–perhaps those responsible for other waterborne illness such as cholera, typhoid and hepatitis. The researchers will also continue testing the filter to make sure only clean water comes out and not any nano-structures.Nano Filters hjgjgf

“So far, our evidence suggests that they don’t come off,” Cui told New Scientist. “It is an interesting academic study,” says nanoengineer Eric Hoek at the University of California, Los Angeles. He says proving that the potentially harmful CNTs [carbon nanotubes] do not leach into the water will be a key step in finding out if it is useful on a practical level. [New Scientist]

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Image: Yi Cui

MIT: New Research Demonstrates how Nanoparticles can Clean Up Environmental Pollutants: Water – Soil

MIT-Pollutant-Nano_0Nanomaterials and UV light can “trap” chemicals for easy removal from soil and water.

Many human-made pollutants in the environment resist degradation through natural processes, and disrupt hormonal and other systems in mammals and other animals. Removing these toxic materials — which include pesticides and endocrine disruptors such as bisphenol A (BPA) — with existing methods is often expensive and time-consuming.

In a new paper published this week in Nature Communications, researchers from MIT and the Federal University of Goiás in Brazil demonstrate a novel method for using nanoparticles and ultraviolet (UV) light to quickly isolate and extract a variety of contaminants from soil and water.

Ferdinand Brandl and Nicolas Bertrand, the two lead authors, are former postdocs in the laboratory of Robert Langer, the David H. Koch Institute Professor at MIT’s Koch Institute for Integrative Cancer Research. (Eliana Martins Lima, of the Federal University of Goiás, is the other co-author.) Both Brandl and Bertrand are trained as pharmacists, and describe their discovery as a happy accident: They initially sought to develop nanoparticles that could be used to deliver drugs to cancer cells.


Nanoparticles that lose their stability upon irradiation with light have been designed to extract endocrine disruptors, pesticides, and other contaminants from water and soils. The system exploits the large surface-to-volume ratio of nanoparticles, while the photoinduced precipitation ensures nanomaterials are not released in the environment.

Image: Nicolas Bertrand

Brandl had previously synthesized polymers that could be cleaved apart by exposure to UV light. But he and Bertrand came to question their suitability for drug delivery, since UV light can be damaging to tissue and cells, and doesn’t penetrate through the skin. When they learned that UV light was used to disinfect water in certain treatment plants, they began to ask a different question.

“We thought if they are already using UV light, maybe they could use our particles as well,” Brandl says. “Then we came up with the idea to use our particles to remove toxic chemicals, pollutants, or hormones from water, because we saw that the particles aggregate once you irradiate them with UV light.”

A trap for ‘water-fearing’ pollution

The researchers synthesized polymers from polyethylene glycol, a widely used compound found in laxatives, toothpaste, and eye drops and approved by the Food and Drug Administration as a food additive, and polylactic acid, a biodegradable plastic used in compostable cups and glassware.

Nanoparticles made from these polymers have a hydrophobic core and a hydrophilic shell. Due to molecular-scale forces, in a solution hydrophobic pollutant molecules move toward the hydrophobic nanoparticles, and adsorb onto their surface, where they effectively become “trapped.” This same phenomenon is at work when spaghetti sauce stains the surface of plastic containers, turning them red: In that case, both the plastic and the oil-based sauce are hydrophobic and interact together.

If left alone, these nanomaterials would remain suspended and dispersed evenly in water. But when exposed to UV light, the stabilizing outer shell of the particles is shed, and — now “enriched” by the pollutants — they form larger aggregates that can then be removed through filtration, sedimentation, or other methods.

The researchers used the method to extract phthalates, hormone-disrupting chemicals used to soften plastics, from wastewater; BPA, another endocrine-disrupting synthetic compound widely used in plastic bottles and other resinous consumer goods, from thermal printing paper samples; and polycyclic aromatic hydrocarbons, carcinogenic compounds formed from incomplete combustion of fuels, from contaminated soil.

The process is irreversible and the polymers are biodegradable, minimizing the risks of leaving toxic secondary products to persist in, say, a body of water. “Once they switch to this macro situation where they’re big clumps,” Bertrand says, “you won’t be able to bring them back to the nano state again.”

The fundamental breakthrough, according to the researchers, was confirming that small molecules do indeed adsorb passively onto the surface of nanoparticles.

“To the best of our knowledge, it is the first time that the interactions of small molecules with pre-formed nanoparticles can be directly measured,” they write in Nature Communications.

Nano cleansing

Even more exciting, they say, is the wide range of potential uses, from environmental remediation to medical analysis.

The polymers are synthesized at room temperature, and don’t need to be specially prepared to target specific compounds; they are broadly applicable to all kinds of hydrophobic chemicals and molecules.

“The interactions we exploit to remove the pollutants are non-specific,” Brandl says. “We can remove hormones, BPA, and pesticides that are all present in the same sample, and we can do this in one step.”

And the nanoparticles’ high surface-area-to-volume ratio means that only a small amount is needed to remove a relatively large quantity of pollutants. The technique could thus offer potential for the cost-effective cleanup of contaminated water and soil on a wider scale.

“From the applied perspective, we showed in a system that the adsorption of small molecules on the surface of the nanoparticles can be used for extraction of any kind,” Bertrand says. “It opens the door for many other applications down the line.”

This approach could possibly be further developed, he speculates, to replace the widespread use of organic solvents for everything from decaffeinating coffee to making paint thinners. Bertrand cites DDT, banned for use as a pesticide in the U.S. since 1972 but still widely used in other parts of the world, as another example of a persistent pollutant that could potentially be remediated using these nanomaterials. “And for analytical applications where you don’t need as much volume to purify or concentrate, this might be interesting,” Bertrand says, offering the example of a cheap testing kit for urine analysis of medical patients.

The study also suggests the broader potential for adapting nanoscale drug-delivery techniques developed for use in environmental remediation.

“That we can apply some of the highly sophisticated, high-precision tools developed for the pharmaceutical industry, and now look at the use of these technologies in broader terms, is phenomenal,” says Frank Gu, an assistant professor of chemical engineering at the University of Waterloo in Canada, and an expert in nanoengineering for health care and medical applications.

“When you think about field deployment, that’s far down the road, but this paper offers a really exciting opportunity to crack a problem that is persistently present,” says Gu, who was not involved in the research. “If you take the normal conventional civil engineering or chemical engineering approach to treating it, it just won’t touch it. That’s where the most exciting part is.”

Silver Nanoparticles: Can Nanotechnology “Nanocomposites” Provide A Low Cost Water Filter?

Silver NP II id35442The effluents of tannery, paint, paper and textile industries containing different type of dyes are often discharged untreated into water bodies. The No. 1 polluter (after agriculture) of clean water is the textile industry, one of the most chemically intensive industries on the planet (read more: “Textile dyeing industry an environmental hazard”; pdf).

The World Bank estimates that 17 to 20 percent of industrial water pollution comes from textile dyeing and finishing treatment given to fabric. Some 72 toxic chemicals have been identified in water solely from textile dyeing, 30 of which cannot be removed. This causes a serious environmental threat to aquatic and human life. Moreover, water treatment plants are very prone to fouling due to microorganism growth in the contaminated water, resulting in higher energy consumption and operating cost.

The development of sustainable, robust, energy-efficient and cost-effective water purification technologies is a challenging task. Conventional practices adopted for water purification – which can be classified into physical, chemical and biological methods – suffer from certain limitations such as high cost, low adsorption capacity, generation of toxic sludge, etc. These technologies – which include coagulation, flocculation, reverse osmosis, membrane separation, oxidation and ozonation, adsorption – are expensive or inadequate to remove dye.

Adsorption with activated carbons, which is a cheap and effective method, has been demonstrated to remove dye from wastewater. But this approach is not suitable for industrial wastewater treatment because activated carbon can only be used once and then it is commonly disposed of in landfills. Moreover, removal of pathogens from treated water requires additional processes like chlorination, ozonation, etc., which increases the cost of treatment.

A possible solution to tackle this problem has been demonstrated by scientists in India. They developed nanotechnology-based water purification using nano-silica-silver composite material as antifouling, antimicrobial and dye adsorptive material. Using this process, pathogenic bacteria and dye present in contaminated water can be treated simultaneously without using any chemicals, high-temperature, pressure or electricity. The team reported their findings in Nanoscale (“Nano-silica fabricated with silver nanoparticles: antifouling adsorbent for efficient dye removal, effective water disinfection and biofouling control”).

nano silica with silver nanoparticles

Schematic illustration of the in situ synthesis (A) of silver nanoparticles on nano-silica support (NSAgNP) by protein extract, (B) immobilization of protein coated silver nanoparticles on nano-silica support by the ‘post-deposition’ route. (© The Royal Society of Chemistry) (click image to enlarge)

“We synthesized a nanosilica supported silver nanocomposite material through ecofriendly protein mediated reduction of nano-silica bound silver ions,” Dr. Sujoy Das from the CSIR-Central Leather Research Institute, India, the paper’s first author, explains to Nanowerk. “The proteins, extracted from Rhizopus oryzae – a zygomycetes fungy, served both as a reducing and a protecting agent for the silver nanoparticles and prevented their oxidation under environmental conditions.

The result is a low-cost, highly effective nanomaterial for sustainable water purification.” The simple, low-temperature bio-synthesis fabrication process – it does not require any elaborate or expensive equipment – works without any chemicals for reduction of silver ions and subsequent production of silver nanoparticles, thus minimizing the environmental load of toxic chemicals during the fabrication of this nanocomposite material. The coating of proteins on the nanoparticles’ surface prevents the leaching of silver ions – which in itself could be a source of eater contamination – and provides long stability of the nanocomposite.

In their report, the research team notes that the as-synthesized nanocomposite demonstrated very high dye removal capacities and exhibited antimicrobial and antifouling properties. The nanocomposite removes the dyes at wide pH, temperature and dye concentration in solution. Moreover, the nanocomposite kills the microorganisms frequently present in the contaminated water.

“Most importantly” says Das, “the silver nanocomposite very efficiently removes dyes and pathogenic microorganisms from water bodies in a single-step operation. In addition, the nanocomposite material could be regenerated after treatment of dye bearing wastewater and the regenerated nanocomposite could be stored and reused for several more cycles.” Nanosilica has a very high surface to volume ratio and contains a large number of surface hydroxyl groups, which provide electrostatic binding energy for dye molecules on its surface.

Combining this with the antibacterial activity of the silver nanoparticles on the surface of nano-silica results in a synergistic effect of the nanocomposite, which is responsible for high removal of dyes and microorganisms from contaminated water. The nanocomposite also prevented attachment of floating microorganisms and inhibited the formation of biofilms on its surface.

This makes it possible to use it for prolonged times in contaminated water. “We believe that the long term antibacterial, antifouling and high dye adsorption properties of our functional nanomaterial are exceptionally promising for the development of high-efficiency and low cost water purification technologies,” concludes Das. After completing their tests, the team is planning to develop a filter for industrial wastewater treatment in larger volume. They also intend to make potable water filters so that people can use it for domestic water purification.

Provided By Michael Berger: Nanowerk


Silver Nanopartilces GAA nano-silica–AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through protein mediated reduction of silver ions at ambient temperature for development of sustainable nanotechnology.

The coated proteins on AgNPs led to the formation of stable NSAgNP and protected the AgNPs from oxidation and other ions commonly present in water. The NSAgNP exhibited excellent dye adsorption capacity both in single and multicomponent systems, and demonstrated satisfactory tolerance against variations in pH and dye concentration. The adsorption mainly occurred through electrostatic interaction, though π–π interaction and pore diffusion also contributed to the process. Moreover, the NSAgNP showed long-term antibacterial activity against both planktonic cells and biofilms of Gram-negative Escherichia coli and Pseudomonas aeruginosa.

The antibacterial activity of AgNPs retarded the initial attachment of bacteria on NSAgNP and thus significantly improved the antifouling properties of the nanomaterial, which further inhibited biofilm formation. Scanning electron and fluorescence microscopic studies revealed that cell death occurred due to irreversible damage of the cell membrane upon electrostatic interaction of positively charged NSAgNP with the negatively charged bacterial cell membrane. The high adsorption capacity, reusability, good tolerance, removal of multicomponent dyes and E. coli from the simulated contaminated water and antifouling properties of NSAgNP will provide new opportunities to develop cost-effective and ecofriendly water purification processes.

Corresponding authors 

Environmental Technology Division, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India
E-mail: sujoy@clri.res.in, sujoydasiacs@gmail.com;
Chemical Laboratory, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Chennai, India
Department of Biological Chemistry, Indian Association for the Cultivation of Science, Kolkata, India
Materials and Surface Science Institute, University of Limerick, Ireland