Project No.: 0317.00.005. 580 Page 1 of 2

Project Name: Nanotechnology Treatment Review 

### CBI?

Yes

No TELEPHONE CALL RECOR D Incoming Outgoing Date: 03/13 /2013 Time: 2:00 am

pm

Company Name: Duke University, CEINT ERG Staff Name: K im 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 o f 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 t here 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 wast ewater 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 the ir 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 nanoma terials? 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 app lication.” N ear

- IR

fluorescence is u sed 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 aga in 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 m edia, hyperspectral imaging can be used to visualize a “halo” around the nanoparticles. The method necessitates looking a t images

of individual pixel s . He referred us to a recently published E S&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 c urrently no standard method to consistently monitor discharges. There are

Need to return call by / at/between and

. Signature: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 nee d 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 combust ion 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 manufa cturer 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 rese arch 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.

Need to return call by / at/between and

. Signature: