Tag Archives: nitrate

Cleaning water with palladium nanoparticle catalysts

A Jan. 16, 2015 news item on Nanowerk describes research into using palladium as a catalyst for water remediation efforts,

One way of removing harmful nitrate from drinking water is to catalyse its conversion to nitrogen. This process suffers from the drawback that it often produces ammonia. By using palladium nanoparticles as a catalyst, and by carefully controlling their size, this drawback can be partially eliminated. It was research conducted by Yingnan Zhao of the University of Twente’s MESA+ Institute for Nanotechnology that led to this discovery.

A Jan. 14, 2015 University of Twente press release, which originated the news item, describes the problem and suggested solution; this was research for a PhD thesis,

Due to the excessive use of fertilizers, our groundwater is contaminated with nitrates, which pose a problem if they enter the mains water supply. Levels have fallen significantly in recent years, as a result of various European directives. In addition, the Integrated Approach to Nitrogen programme was launched in various Dutch nature reserves at the start of January. Tackling the problem at source is one thing, but it will still be necessary to treat the mains water supply. While this can be achieved through biological conversion – bacteria convert the nitrate to nitrogen gas-, this is a slow process. Using palladium to catalyse the conversion of nitrate to nitrogen speeds up the process enormously. However, this reaction suffers from the drawback that it produces a harmful by-product – ammonia.

Exposed surface

The amount of ammonia produced appears to depend on the method used to prepare the palladium and on the catalyst’s physical structure. Yingnan Zhao decided to use nanometre-sized colloidal palladium particles, as their dimensions can be easily controlled. These particles are fixed to a surface, so they do not end up in the mains water supply. However, it is important to stop them clumping together, so stabilizers such as polyvinyl alcohol are added. Unfortunately, these stabilizers tend to shield the surface of the palladium particles, which reduces their effectiveness as a catalyst. By introducing additional treatments, Yingnan Zhao has managed to fully expose the catalytic surface once again or to manipulate it in a controlled manner. This has resulted in palladium nanoparticles that can catalyse the conversion to nitrogen, while producing very little ammonia. This has brought the further development of catalytic water treatment (in compact devices for home use, for example) one step closer.

Yingnan Zhao, who is from Heze, Shandong, China, conducted his research in Prof. Leon Lefferts’ Catalytic Processes and Materials group. He defended his thesis, which is entitled “Colloidal Nanoparticles as Catalysts and Catalyst Precursors for Nitrite Hydrogenation” on Thursday 15 January [2015].

I trust Zhao successfully defended this thesis and perhaps more importantly helped to develop a new and better method for water remediation made necessary by the effects of fertilizers.

Nanomaterial use in construction, in coatings, in site remediation, and on invisible planes

Next to biomedical and electronics industries, the construction industry is expected to be the most affected by nanotechnology according to a study in ACS (American Chemical Society) Nano (journal). From the news item on Azonano,

Pedro Alvarez and colleagues note that nanomaterials likely will have a greater impact on the construction industry than any other sector of the economy, except biomedical and electronics applications. Certain nanomaterials can improve the strength of concrete, serve as self-cleaning and self-sanitizing coatings, and provide many other construction benefits. Concerns exist, however, about the potential adverse health and environmental effects of construction nanomaterials.

The scientists analyzed more than 140 studies on the benefits and risks of nanomaterials. …

The article in ACS Nano is titled, “Nanomaterials in the Construction Industry: A Review of Their Applications and Environmental Health and Safety Considerations.

Still on the construction theme but this time more focused on site remediation, here’s a story about sulfur-rich drywall which corrodes pipes and wiring while possibly causing respiratory illness. From the news item on Nanowerk,

A nanomaterial originally developed to fight toxic waste is now helping reduce debilitating fumes in homes with corrosive drywall.

Developed by Kenneth Klabunde of Kansas State University, and improved over three decades with support from the National Science Foundation, the FAST-ACT material has been a tool of first responders since 2003.

Now, NanoScale Corporation of Manhattan, Kansas–the company Klabunde co-founded to market the technology–has incorporated FAST-ACT into a cartridge that breaks down the corrosive drywall chemicals.

Homeowners have reported that the chemicals–particularly sulfur compounds such as hydrogen sulfide and sulfur dioxide–have caused respiratory illnesses, wiring corrosion and pipe damage in thousands of U.S. homes with sulfur-rich, imported drywall.

“It is devastating to see what has happened to so many homeowners because of the corrosive drywall problem, but I am glad the technology is available to help,” said Klabunde. “We’ve now adapted the technology we developed through years of research for FAST-ACT for new uses by homeowners, contractors and remediators.”

The company has already tested its new product and found that corrosion was reduced and odor levels dropped to almost imperceptible. There are plans to use the company’s technology in the Gulf Coast and elsewhere there are airborne toxic substances.

In Europe, Germany has plans to introduce new concrete paving slabs that reduce the quantity of nitrogen oxide in the air. From the news item on Nanowerk,

In Germany, ambient air quality is not always as good as it might be – data from the federal environment ministry makes this all too clear. In 2009, the amounts of toxic nitrogen oxide in the atmosphere exceeded the maximum permitted levels at no fewer than 55 percent of air monitoring stations in urban areas. The ministry reports that road traffic is one of the primary sources of these emissions.

In light of this fact, the Baroque city of Fulda is currently embarking on new ways to combat air pollution. Special paving slabs that will clean the air are to be laid the length of Petersberger Strasse, where recorded pollution levels topped the annual mean limit of 40 micrograms per cubic meter (µg/m3) last year. These paving slabs are coated with titanium dioxide (TiO2), which converts harmful substances such as nitrogen oxides into nitrates. Titanium dioxide is a photocatalyst; it uses sunlight to accelerate a naturallyoccurring chemical reaction, the speed of which changes with exposure to light.

They’ve already had success with this approach in Italy but Germany has fewer hours of sunshine and lower intensities of light so the product had to be optimized and tested in Germany. Testing has shown that the effect for Germany’s optimized paving slabs does not wear off quickly (it was tested again at 14 months and 23 months). Finally, there don’t seem to be any environmentally unpleasant consequences. If you’re curious about the details, do click on the link.

One last item, this time it’s about a nano-enabled coating that’s a paint. An Israeli company has developed a paint for airplanes that can make them invisible to radar. From Dexter Johnson’s July 14, 2010 posting on Nanoclast,

No, we’re not talking about a Wonder Woman-type of invisible plane, but rather one that becomes very difficult to detect with radar.

The Israel-based Ynetnews is reporting that an Israeli company called Nanoflight has successfully run a test on dummy missiles that were painted with the nano-enabled coating and have shown that radar could not pick them up as missiles.

The YnetNews article rather brutally points out that painting an aircraft with this nanocoating is far cheaper than buying a $5 billion US-made stealth aircraft. Of course, it should also be noted that one sale of a $5 billion aircraft employs a large number of aeronautical engineers, and the high price tag also makes it far more difficult for others to purchase the technology and possess the ability to sneak up on an enemy as well.

You can read more and see a picture of Wonder Woman’s invisible plane by following the link to Dexter’s posting.