1. STANDARD OPERATING PROCEDURE
MOLECULARLEVEL MIXING OF CARBON
NANOTUBES THROUGH ACID PURIFICATION AND
FUNCTIONALIZATIONOF CARBON NANOTUBES
College/Dept: Building/Room:
Laboratory Name: Revision:
Principal Investigator: Janelle Wharry Author: Patrick Warren
Before the worked detailed in this procedure may begin, the intended user must read and understand this document.
This document must be approved by the PI, the college’s safety liaison, and EHSS.
Any changes to this document, however minor, must be submitted for approval by the PI, the college’s safety liaison,
and EHSS.
The “buddy system” will be in place whenever any work is conducted.
Approval
Intended
User:
Patrick Warren
Name, Title Signature Date
Tom Statkus
Name, Title Signature Date
Reviewed and
Approved by:
Name, Title Signature Date
Name, Title Signature Date
Overview
Hydrofluoric acid (HF) will be used to purify and remove any metal remnants from the carb nanotube production process
Nitric acid will be used to introduce defect sites to the carbon nanotube surface where functional groups can be added
Sodium dodecylbenzene sulfonate (SDBS) will be used to suspend carbon nanotubes and modify the surface of the
CNTs
Fe(NO3)3 will be dissolved in the CNT suspension so that Fe ions can attach to the functional sites on the CNT surface
Ammonia will be used to maintain a pH of 9.5 in the CNT solution
Scope
For the purposes of this procedure, HF and concentrated nitric acid will be used in the purification and functionalization

2. of carbon nanotubes. SDBS will be used to modify the surface of the carbon nanotubes (CNTs). Fe(NO3)3 will be used in
solution to attach iron to functionalized CNTs. Ammonia will be used to raise the pH of the solution to 9.5.
Potential Hazards
Chemical ☐ Thermal ☐ Hydraulic ☐ Electrical ☐ Slip/Trip ☐ Biological
☐Mechanical ☐ Radiation ☐ Pneumatic Fire ☐ Fall ☐ Other
Hazard Specifics: Hydrofluoric acid is a strong acid that is extremely corrosive. It readily reacts with Calcium and
attacks bone, organs and kidneys. Exposure may not be apparent so HF should be handled with
extreme caution to avoid exposure. Exposure should be dealt with immediately.
Nitric acid is a highly corrosive and oxidative agent. It can cause severe burns to skin and eyes and
may cause permanent blindness. When inhaled nitric acid can be extremely damaging to upper
respiratory tract and mucous membranes. Inhalation may cause spasms, inflammation, and edema
of larynx or bronchi and pneumonitis. Other symptoms include burning of throat, wheezing, and
shortness of breath, headache and nausea. Large doses may cause collapse, coma, and even
death.
SDBS is a surfactant that is irritating to the skin, damaging to eyes, toxic if swallowed or inhaled. It
is also toxic to aquatic life so release into environment should be avoided
Fe(NO3)3 is an oxidizing agent and a skin irritant. Should be kept separate from incompatible
chemicals. It can be toxic and would target the blood if introduced to the blood stream. Can cause
eye/skin irritation, burning mouth and throat if swallowed, nausea, vomiting, damage to mucous
membranes and coughing, wheezing, and shortness of breath if inhaled.
Ammonia is extremely alkaline and corrosive to all tissue. Skin contact may result in skin irritation,
redness pain, and skin burns. Inhalation could cause serious mucous membrane and upper
respiratory damage. Symptoms include burning, coughing, wheezing, shortness of breath,
headache nausea and vomiting. Death may result from edema of larynx and bronchi, chemical
pneumonitis and pulmonary edema. Ingestion can cause burns to mouth, through and stomach and
may lead to death. Can cause sore throat, vomiting, and diarrhea. Eye contact can cause blurry
vision, redness, pain, eye tissue damage, and blindness.
Engineering Controls (EC)
Fume hood ☐ Biosafety Cabinet ☐ Other Local Exhaust Shielding Other
EC Specifics: For hydrofluoric acid and nitric acid use: Fume hood should be used as a precaution for HF toxic
fumes. Shielding should be used in case of splashing of the chemical during carbon nanotube
functionalization process. Wet bench should be used to prevent spilling on the ground. If fume hood
and wet bench cannot be used simultaneously other local exhaust will be necessary.
For SDBS and Fe(NO3)3: Fume hood should be used due to toxicity to respiratory system.
Training Requirements – except for classroom lab safety, must be completed prior to performing the procedure
☐ Classroom Laboratory Safety Awareness ☐ Radiation Worker
 Online Safety Topics
(specify): Chemical Safety
Training
☐ Lab/Work Group Specific Training
(specify):
Other (specify): Training and walk through of clean room

3. Personal Protective Equipment (PPE)
 Safety
glasses
 Safety
goggles
 Face shield & safety
glasses
 Face shield & safety
goggles
 Lab coat  Apron ☐ Tyvek suit ☐ Tyvek sleeves
 Gloves
 Leg
coverings
☐ Hard hat ☐ Hearing protection
☐Respirator  Shoes ☐ Fall protection ☐ Other
PPE Description: Elbow length natural rubber gloves as well as nitrile gloves underneath should be used. A natural
rubber apron should also be used as well as closed toed closed heel rubber or leather shoes.
(For nitric acid Viton Gloves should be used instead of Nitrile gloves for concentrations
>70%)
For SDBS, use of fume hood, nitrile gloves, lab coat, long sleeves, and shoes that cover entire
foot will be sufficient
For Fe(NO3)3 use fume hood, nitrile gloves, lab coat, long sleeves, and shoes that cover entire
foot.
For Ammonia, ventilation is necessary. Working under a chemical fume hood will be sufficient.
Impervious protective clothing should be used including boots, gloves, lab coat, apron or
coveralls. Chemical safety goggles and/or face shield should also be used. A safety shower and
eye wash fountain should be accessible.
Equipment, Materials, Supplies, & Facility Requirements
HF acid will be contained in Nalgene or polypropylene containers during the carbon nanotube bathing process as well as
for storage of the chemical. Rubbermaid bottle carriers or Nalgene secondary containers should be used in the transport
of HF acid. Nitric acid will need to be contained in a glass container.
For SDBS Nalgene/polypropylene or glass containers will be sufficient for storage containers and measurement
containers. Lids on containers should be fastened tightly and stored away from oxidizers
For Fe(NO3)3 Nalgene/polypropylene or glass containers will be sufficient for storage containers and measurement
containers. Lids on containers should be fastened tightly.
For Ammonia, Glass containers will be sufficient for storage and measurement.
Eye wash station, quick drench station, fire extinguisher should be accessible for use of all chemicals discussed in this
document.
Handling, Work Area & Storage Requirements
HF and nitric acid should be stored in corrosive chemical cabinet. Chemicals should never be stored above eye level.
Chemicals should be stored in Nalgene or polypropylene container as well as Rubber maid or Nalgene secondary
containment. Lids should be tightly closed tightly on all containers. Should not be stored with oxides, organic chemicals,
metals or bases.
For SDBS further processing of solid material may form combustible dusts. To prevent build up of combustible dusts
SDBS storage container should be stored in well-ventilated dry area. Storage container should be fastened tightly. SDBS
is incompatible with oxidizing agents so it should not be stored near oxidizing agents.
For Fe(NO3)3, it should be stored in oxidizer storage area (yellow storage area) with other oxidizers and away from any
combustible materials. Should be stored in cool, dry, well ventilated locked store room away from incompatible materials.
For Ammonia, should be stored below 25 C. Container should be tightly fastened. It should be stored in a dry and
ventilated area.

4. Emergency Response Equipment & Supplies
 Eyewash  Fire extinguisher  First aid kit  Calcium gluconate gel (HF use)
 Safety
shower
 Fire blanket  Spill kit ☐ Emergency gas shutoffs
 Drench hose ☐ Other:
Description: Acid clean up kit needed – hydrofluoric acid compatible supplies to clean up 500mL spill.
In case of combustible dust build up suitable fire extinguisher should be accessible (water spray,
alcohol resistant foam, dry chemical or carbon dioxide)
Decontamination & Waste Disposal
Classified as extremely hazardous substance. Containers which held HF in past should be disposed of as hazardous
materials. They should have an online hazardous waste tag attached to the container. Safety gloves that came into
contact with HF should be disposed of as dry hazardous waste. Dry hazardous waste should be double bagged and
tagged with an online waste tag. Each hazardous waste container should have the following:
 The words “Hazardous Waste”
 The waste name, building and room number where the material was generated
 The chemical constituents contained. A generic title may be used only if specific waste profiles have been
established with EHSS (i.e., in teaching labs or long term research projects).
All chemicals be disposed of through EHSS with use of chematix software
Spill Response
During clean up, respiratory protection should be worn to avoid inhalation. If able to and if trained to do so,
further spillage should be prevented. Spill should not be allowed to enter any drains in the area. The spill
should be soaked up using inert absorbent material and then disposed of as hazardous material. Clean up
materials should be kept in containers that are compatible with the chemical and sealed. Personal protective
equipment must be worn during clean up. Amount spilled should be assessed as soon as possible. It may also
be necessary to call emergency response (911) and EHSS. Neutralizing agents such as sodium carbonate
and liquid absorbing material such as vermiculite, sand, kitty litter are effective in spill clean up. Clean up
material should be double bagged in transparent bags and labeled hazardous
For SDBS, PPE should be used during spill clean up. Inhalation of dust formed by SDBS should be avoided.
Further leakage or spillage should be prevented if it is safe to do so. Spillage should not be allowed to enter
drains. Environmental exposure must be prevented. Clean up should not create dust. Clean up should be
done by sweeping up and shoveling. The spilled SDBS should be closed in a suitable container and disposed
of according to disposal instructions outlined in the disposal section.
For Ammonia, area where spill occurred should be well ventilated. Appropriate PPE should be used. Liquid
should be collected in appropriate container, and absorbed with inert material such as vermiculite or dry dirt.
Water spray should be used to keep cool, absorb, and disperse vapor. Do not flush liquid waste down the
drain.
Additional Safety Information

5. If HF comes into contact with skin, the affected area should be washed with water immediately after the exposure.
Affected area should be rinsed with water for 5 minutes and then coated in calcium gluconate gel. Any contaminated
clothing should be removed immediately. Emergency responders should be called immediately and calcium gluconate gel
should be applied to the affected area every 15 minutes until the emergency responders arrive.
For nitric acid, if skin is exposed wash with plenty of water for 15 minutes and remove any contaminated clothing. If eyes
are exposed rinse thoroughly with water for at least 15 minutes. Lift upper and lower eyelids and remove contact lenses.
Emergency response should be called immediately and eye rinsing should continue while being transported to the
hospital. If swallowed do not induce vomiting. Rinse mouth with water and contact and consult physician.
For SDBS, if inhaled move exposed person(s) to fresh air environment, if not breathing call emergency responders and
give artificial respiration. In case of skin exposure rinse with plenty of water for 15 minutes and consult a physician.
References
Hydrofluoric Acid SOP, UC Berkley
Nitric Acid SOP, UC Berkley
Hydrofluoric Acid MSDS, Sigma Aldrich
Nitric Acid MSDS, Sigma Aldrich
Sodium Dodecylbenzene sulfonate MSDS, Sigma Aldrich
Fe(NO3)3 MSDS, Scholar Chemistry
Hazardous Waste Management Manual. Boise State University

6. Procedure
STEPS
Potential Hazards
EC, Haz. Mitigation
Device, PPE
1. Acid Treatment of Carbon Nanotubes Acid splash resulting in
contact with skin (on face or
other exposed parts of body)
to anyone in the immediate
vicinity.
Acid Spill resulting in
contamination and damage
of surrounding area,
equipment, and to facility’s
drainage.
For emergency involving
direct contact between acid
and skin please refer to
Potential Hazard, Emergency
Response, and Additional
Safety Information sections
Elbow length natural rubber
gloves as well as nitrile gloves
underneath should be used. A
natural rubber apron should
also be used as well as
closed toed closed heel
rubber or leather shoes. (For
nitric acid Viton Gloves
should be used instead of
Nitrile gloves for
concentrations >70%)
Fume hood and wet bench
will also be used
a. Collect 50 g ( 43.48 mL) (48wt%) HF in Nalgene beaker and 150 g of water in separate beaker.
b. HF and water will be combined in one large Nalgene beaker. Water will be poured in first followed by HF.
c. 0.4 g of carbon nanotubes will be bathed in 50 g (48wt%) hydrofluoric acid and 150 g of water under continuous
stirring with magnetic stir bar for 2 hours in Nalgene or polypropylene beaker at room temp.
d. After hydrofluoric acid bath, nanotubes will be filtered through 0.65-micron filter while being rinsed with distilled
water until HF has been rinsed from CNTs. CNTs will then be scraped from filter into glass beaker. ~ 200 mL of
Nitric acid will be added to glass beaker and carbon nanotubes will be bathed in concentrated nitric acid for 2
hours.
e. Mixing will be done on wet bench for the duration of the mixing and acid treating process.
Potential Hazards
EC, Haz. Mitigation
Device, PPE
2. Filtering of carbon and water washing of
carbon nanotubes
Acid splash resulting in
contact with skin (on face or
other exposed parts of body)
to anyone in the immediate
vicinity.
Acid Spill resulting in
contamination and damage
of surrounding area,
For emergency involving
direct contact between acid
and skin please refer to
Potential Hazard, Emergency
Response, and Additional
Safety Information sections
For spills please refer to Spill
Response

7. equipment, and to facility’s
drainage.
a. After nitric acid bath carbon nanotubes should be filtered through 0.65 micron filter while being washed with
distilled water until impurities have been removed and remaining acid has been neutralized. pH of rinses will be
checked periodically with pH probe until pH reaches ~7. After pH is checked each time waste solution will be
collected in separate Nalgene waste container.
Potential Hazards
EC, Haz. Mitigation
Device, PPE
3. Dry filtered CNTs in oven Contents will be hot when
drying process finishes.
Potential for burns
Handle dried powder with
oven mits. Wait until cooled to
collect CNT powder in
different container
a. Filtered CNTs will be collected on aluminum foil and heated in an oven for 5 hours at 100 C to evaporate
remaining liquid from CNT surface
Potential Hazards
EC, Haz, Mitigation
Device, PPE
4. Surface modification of CNTs using sodium
dodecylbenzene sulfonic acid.
Accidental spill of SDBS
may cause slip and fall,
leakage to drains resulting in
environmental exposure
Skin exposure from splash
or spill
Eye exposure from splash or
spill
Use of fume hood, nitrile
gloves, lab coat, long sleeves,
and shoes that cover entire
foot will be sufficient
For spills please refer to Spill
Response

8. a. 1 wt% SDBS aqueous solution will be mixed in the following way: 500 g solution ~ 500 mL solution. Mix 495 g of
water (495 mL Water) with 5 grams of SDBS to make 1 wt% SDBS aqueous solution.
b. After filtering the acid treated CNTs, the surfaces of the CNTs will be modified using SDBS. Acid treated CNTs
will be poured into and homogenously dispersed in 1 wt% SDBS aqueous solution for 4 hours. Quantity of CNTs
added will depend on yield from acid treatment and filtering steps This step will be done at room temperature.
The entire duration of the dispersion process will take ~ 4 hours.
Potential Hazard
EC, Haz, Mitigation
Device, PPE
5. SDBS adsorbed CNTs dispersed into 50 ml 0.1
M Fe(NO3)3
Accidental spill of Fe(NO3)3
leakage to drains resulting in
environmental exposure
Skin exposure from splash
or spill
Eye exposure from splash or
spill
Use fume hood, nitrile gloves,
lab coat, long sleeves, and
shoes that cover entire foot.
For spills please refer to Spill
Response
a. After further rinsing and drying, 1 g SDBS adsorbed CNTs was dispersed into 50 ml 0.1 M Fe(NO3)3 (Fe(NO3)39H20)
(purchased from Sigma Aldrich) solution under ultrasonication for one hour in fume hood.
Potential Hazard
EC, Haz, Mitigation
Device, PPE
6. Ammonia solution added drop wise to suspension
to raise pH
Ammonia is a noxious
chemical can cause damage
to respiratory system can
cause skin burns and
redness
Should be used under a fume
hood to avoid inhalation of
ammonia
Gloves, lab coat, pants and
shoes that provide full
coverage should be used

9. a. 2.5 wt% ammonia solution will be made in the following way: Add 5 g of NH4NO3 and 2.5 g NaOH
(0.0625 mol each; 1:1 mol ratio) in a gas generator flask to produce 0.0625 mol Ammonia (1.064 g) in
0.0625 mol H2O (1.126 g). Add 486.37 g H2O to solution to produce 2.5wt% ammonia solution.
b. 2.5 wt% Ammonia solution will be added drop wise to the CNT suspension from step 5 while agitated
vigorously until the pH of the solution reaches 9.5 pH. This step will be done at room temperature.