Project No.: 0317.00.005.580 Page 1 of 2

Project Name: Nanotechnology Treatment Review CBI?

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TELEPHONE CALL RECORD

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Outgoing

Date: 03/13/2013 Time: 2:00 am

pm

Company Name: Duke University, CEINT ERG Staff Name: Kim Wagoner, Eva Knoth

Contact Name: Dr. Mark Wiesner Contact Phone Number: 919-660-5292

General Subject: Request for Information on Nanomaterials Research

TOPICS DISCUSSED AND ACTION TAKEN

On March 13, 2013, we called Dr. Wiesner to discuss information about nanomaterials and current research at 

the Center for the Environmental Implications of NanoTechnology (CEINT). We first introduced Dr. Wiesner 

to EPA’s effluent guidelines process and our current evaluation of nanomaterials in industrial wastewater. We 

then asked him what industries or specific nanomaterials he thought that we should focus our attention on in 

terms of industrial wastewater production. He suggested screening based on nanomaterials with the largest 

production quantities, such as metal oxides (i.e. silver, zinc and titanium oxides) and carbon nanotubes (CNT). 

We then reviewed our study questions: Are there technologies that can treat nanomaterials in wastewater 

discharges? Are any conventional technologies effective at treating nanomaterials? He replied that carbon-based 

nanomaterials, like fullerenes and CNTs, will undergo transformations within a wastewater treatment plant 

(WWTP) to generally increase their affinity to water. Liquid-solid separation technologies can be used to 

remove these from water. Conventional treatments, such as filters and coagulants, provide good removal for 

these nanomaterials. In addition, column tests with activated sludge performed within CEINT have

demonstrated that the majority of nanomaterials partition into the sludge. Silver oxide nanoparticles undergo 

significant transformations (specifically sulfidation) within a WWTP. Sulfidation vastly reduces their toxicity 

impacts. Zinc oxides tend to form complexes with phosphorus species.

We asked several related questions regarding analytical techniques. Are there analytical techniques available to 

detect and characterize nanomaterials? Through your research, what methods have you found to be most 

consistent? What methods are most promising for future development? Dr. Wiesner responded that all the 

current methods of detection are lab intensive. None are ready for “prime time application.” Near-IR 

fluorescence is used to detect the presence of single-walled carbon nanotubes, but not multi-walled carbon 

nanotubes. The residual catalysts (e.g. iron, nickel, cobalt) used to produce nanomaterials could be used to track 

nanoparticles in a waste stream; however, these are often present in wastewaters so there would be no way to 

directly measure the metal catalyst source alone. For aqueous media, single particle ICP-MS can be used to 

detect and count particles greater than 30 nm, but again this is a very lab intensive measure and is not adapted 

for field monitoring. In terms of regulations, one could measure total metals in a wastewater sample and analyze 

the sample under an electron microscope to sort out the nanoparticles. For complex media, hyperspectral 

imaging can be used to visualize a “halo” around the nanoparticles. The method necessitates looking at images 

of individual pixels. He referred us to a recently published ES&T article entitled “Detection, Characterization, 

and Abundance of Engineered Nanoparticles in Complex Waters by Hyperspectral Imagery with Enhanced 

Darkfield Microscopy.”

We then asked about his general thoughts on the potential development of nanomaterial discharge regulations. 

Dr. Wiesner responded that there is currently no standard method to consistently monitor discharges. There are 

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many toxicity studies completed, but the risks have not been clearly identified, and in particular the exposure 

path is not well understood. Any current means of regulation would need to target production of nanomaterials, 

not their discharge. Additionally, nanoparticles are constantly dissolving and reforming in aqueous media. 

We asked if Dr. Wiesner was aware of any aqueous waste streams from primary or downstream production. Dr. 

Wiesner replied that in primary production CNTs are produced via a combustion process and metal oxides are

produced using heated spray plasma. He indicated that it is likely that atmospheric or solid emissions would be 

of greater concern, unless the manufacturer employed a wet scrubber. Downstream production is more likely to 

have a liquid waste stream because they manufacture the products with the nanomaterials in solution. He noted 

that end of life activities are also an issue. He commented to expect research on value chains to be published in 

the near future (not from CEINT) and that this research interface with social science could be very useful to us.

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