# Presentation: 084114

## Descaling, debulking, debundling, catalyst removal and shortening of carbon nanotubes

- John P. Marino, Ph.D. (NIST/UMBI)
- Gary G. Giulian, M.D. (NIST-contractor/UMBI)

## Realizing the Potential of Carbon Nanotubes

**Production**** **
- 1) yield
- 2) purity
- 3) specific  properties

**Processing**
- 1) purification
- 2) sizing
- 3) sorting
- 4) storage

**Manipulation**
- 1) Chemical Modification
- 2) Structural Assemblies

## Processing of Carbon Nanotubes:What is the Problem? 

**Problem:**
- 	CNT’s (both high and low grade materials) are not produced as individual, catalyst-free “tubes” but as **mixed** **bundles of tubes with metallic catalysts and carbon shell (amorphous carbon).**
**Technologies:**
- 	Establish methodologies to generate debundled, debulked, size fractionated CNTs that are:
- 		Scalable
**	****	**Non-toxic (‘green’)
**	****	**Ease of post-processing manipulation
- 		and use
- 		Cost-effective  $$$

## Processing of Carbon Nanotubes: Cost Consideration & bottlenecks

- 	The removal of the metallic catalysts and amorphous carbon is a significant barrier to isolating a pure population of CNT’s.
- 	As a result, current commercial CNT’s grades of >95% pure tubes (by weight) cost between $500-$1000/gm.
- 	By comparison, at a price of $925 per ounce (1 ounce = 28.35 grams) – pure CNT’s are ~ 14 - 28 times the price of Gold!
- 	**Current cost of purified, processed CNTs limits many potential applications**

## 1) Grit shearing, rotating mesh 900 to CNT flow (micro/ submicro-scale [100 m to 10 nm])
2) Phase separation glycerol overlay on Neodymium magnets – 1500 gauss. (mixed micro/nanoscale)
3) SDS-electrophoresis and/or flow sorting w/rotating dialysis/filtering membranes (nano-scale [10 nm – <1 nm])
4) “Dry” or “Wet” Final Samples 

**2) Phase separation glycerol overlay on Neodymium magnets – 1500 gauss. (mixed micro/nanoscale)**
**3) SDS-electrophoresis and/or flow sorting w/rotating dialysis/filtering membranes (nano-scale [10 nm – <1 nm])**
**4) “Dry” or “Wet” Final Samples**** **

**Processing of Carbon Nanotubes: **** New approaches to the problem.**

**Scalable: **_**kilogram**_** batch size**
**Processing Cost: < **_**$1 per gram**_
**Startup Infrastructure Costs:  < $1000**

## Grit shearing, rotating mesh 900 to CNT flow 

- 50 **μm **mesh

**Grit shearing, rotating mesh 90****0**** to CNT flow **
**(micron/submicron-scale [100 ********m to 10 nm] )**

- Motion of particles through the filters. The rotating motion self-cleans the membrane and prevents clogging.

- Alfred Ledford (device fabrication)

## An example of an AP SWCNT sample after grit shearing/micron filtering

**An example of an AP SWCNT sample after grit shearing/micron filtering**

**> 50 μm**

**<50 to 1 μm**

**< 1 μm**

**1g  AP SWCNT, 1% SDS  - 250 ml H****2****O total volume**

## Magnetic Separation of CNT after Grit Shearing & Rotary Filtration

**24 hours of magnetic separation ( 1 ********m fraction)**

**Amorphous carbon *****(frass)***

**CNTs**

**catalyst/grit**

**tube bundles**

**Magnetic Separation of CNT after Grit Shearing & Rotary Filtration**

**SDS/glycerol**
**Gradient**
**Increasing**
**Concentration**

- Process Container
- Volume 		500 ml
- I.D. 		6.8 cm **(2.7 inches)**

**500 Gauss **
**‘****Neomagnet’**

## Applications: Nano-Composites

- http://www.zyvex.com/Products/CNEE_001a.html

- Carbon fibers

**Pre-tensioned processed CNTs filing a gap: *****More tubes, better alignment and finer bundles***

**“****The nanotubes fill in resin gaps, thereby supporting the weakest portion of the composite material.**”

- SEM Image: Sam Jones, Michael Postek (MEL)

- CNTs

- ‘Nanoblocks’

## Applications: Industrial Crystal Seeding

_**(a)**_

_**(b)**_

**Applications: Industrial Crystal Seeding**

- Nucleation of glycine crystals using processed CNTs10 – 100x larger crystals

- Processed CNT material trapped inside a Glycine crystal (a) dark black core.

## Applications: Testing EHS Risks of Nanoparticles

- Model system:* Caenorhabditis elegans*

- Processed CNTs are not toxic as judged by viability, lifespan and progeny

**Viability**
**(N=500)**

**# progeny**
**(N=50)**

**lifespan**
**(N=50)**

**0%**

**20%**

**40%**

**60%**

**80%**

**100%**

**>99%**

**>99%**

**241**

**249**

**13.8**
**days**

**13.3**
**days**

- Harold Smith (UMBI)

## Commercially viable CNT processing technologies 

Applications enabled by the sizing, descaling and sorting of CNTs:
crystal growth seeding 
toxicology & safety studies
nanocomposites

drug delivery
magnetic alignment/liquid crystals 
nano-particle recover from waste oil
lithium storage (nano-battery)
NIST nanostandards

- Commercially viable CNT processing technologies
- Applications enabled by the sizing, descaling and sorting of CNTs:
- crystal growth seeding
- toxicology & safety studies
- nanocomposites
- drug delivery
- magnetic alignment/liquid crystals
- nano-particle recover from waste oil
- lithium storage (nano-battery)
- NIST nanostandards

**Production **
- 1) yield
- 2) purity
- 3) specific  properties

**Processing**
- 1) purification
- 2) sizing
- 3) sorting
- 4) storage

**Applications**
- 1) Chemical Modification
- 2) Structural Assemblies