Detection of nanoparticles
Maja Remškar1, Ivan Iskra1, Janja Vaupotič1, Griša Močnik2
1Jozef Stefan Institute, Jamova 39, Ljubljana, Slovenia2Aerosol d.o.o., Kamniska 41, Ljubljana, Slovenia
1. Special properties of nanoparticles
2. Direct observation of nanoparticles (microscopy)
3. Indirect observation (scattering)
4. Detection of nanoparticles
5. Demonstration of nanoparticle detectors (Ivan Iskra, Grisa Mocnik)
Unvisible
Airborn
Reactive
NANOPARTICLE Fast
Brownian motion
velocity m-1/2 r – 3/2
mCarbon (10 nm) = 3.10-22 kg
v (RT) = 11 m/s
Eye: resolution - 0.1 mm
Optical microscope: 300 nm (3000 x)
Transmission electron microscope: 0.12 nm – 1.5.106 x
- Large surface area/mass ratio
- Quantum effects
Number of NPs in cm3:
-Office: 1.104- 4.104
-Welding (varjenje) : 4.106
-Grinding (brušenje): 2.105
-Smoking >1.108
exahalation
Agglomeration of nanoparticles
50 m
2 nm
- Self-assembly
of MoxSyIz
nanotubes
- Agglomeration of TiO2 during the production process
NO data on agglomeration and recrystallization in:
• bio-compatible solvents
• during the transition through the cell membrane
• inside the cell and its nucleus
Agglomeration of WOx nanowires during evaporation of solvent
Chemical activity of nanoparticles
Strongly depends on the ration of surface atoms to volume atoms
Diameter NS / NV atoms
8 nm 7 %
1 nm 58 %
Physical and Chemical properties ofnanoparticles could influence their potential risk.• Composition• Size• Shape• Surface properties (possibility of adsorbedspieces)• Bulk properties- chemistry
Origin of nanoparticles and where we meet them:
• intentionally produced - engineered: cosmetics, food, detergents, textile, water protective films
• non intentionally produced:
- a side product in industrial production (grinding, soldering, milling)
- combustion of bio-mass
- emission from diesel engines
• natural: erosion, desert powder, viruses
Nanoparticles have always been presentin the environmentCombustion processes in the last 200years have added to the amount ofmanmade nanoparticles entering theenvironment
• How can we determine and measure this?
• Is the overall amount of nanoparticles in the environment set to increase?
FROM EVER
Limited data and guidelines are available for handling nanoparticles in occupational settings as well as research laboratories.
For example, guidelines for the selection of respiratory protection for specific types of nanoparticles are lacking.
Workplace exposure
Large concentrations of nanoparticles may be present in occupational environments, which deserve particular attention from the standpoint of exposure.
Powered blouse respiratorwww.nanosafe.org
A number of organisations including CEN, ISO or OECD are working to develop and standardize instruments and test methods for the support of appropriate health, safety and environment legislation and regulations of nanomaterials. It includes work on the development and standardisation of:
· Instruments and test methods for measurement and identification of airborne nanoparticle in the workplace and the environment;· Test methods to characterize nanomaterials;· Protocols for toxicity and eco toxicity testing;· Protocols for whole life cycle assessment of nanomaterials, devices and products;· Risk assessment tools relevant to the field ofnanotechnologies;· Test methods to assess the performance efficiency of engineered and personal control measures;· Occupational health protocols relevant tonanotechnologies.
STM-Scanning tunneling microscope
10
-for studying surfaces at atomic level. -for good resolution is considered to be 0.1 nm lateral resolution and 0.01 nm depth resolution
www.iap.tuwien.ac.atwww.ijs.si
Atomic Force Microscopy
http://mrsec.wisc.edu
Carbon nanotubes- non-contact AFM
Interdepartmental Center for Electron Microscopy, IJS:
JEM-2010F, 200 keV
15 nm TiO2
Sigma-Aldrich
Light scattering
Large particles: small angle of scatteringSmall particles: large angle of scattering
Dynamic light scattering
By knowing the incident light frequency and measuring the scattered light frequency to determine the shift, we can calculate particle size
Detection principlesDetection
Condensation Electrometers
Number concentration
Number of particles
Net charge
15-500 nmMax 105 NPs/cm3
Prize: 7.000 Eur
High voltage source
Virtual ground
Exhaust flow
Corona discharge
Current carried away by particles
Tailpipe
Electrometer
High voltage source
Virtual groundVirtual ground
Exhaust flow
Corona discharge
Current carried away by particles
Tailpipe
Electrometer
Dekati ETaPS sensor for diesel exhaust
Current Monitoring MethodCondensation Particle Counter (CPC)
• Old technology--based on cloud chamber effect• Grow nm particles in saturated alcohol or water atmosphere• Then use optical counter to determine number concentration• First widespread application was in clean rooms• Needed to count very low levels
• CPCs are now common in air pollution research studies and to monitor industrial processes• CPCs in routine air monitoring are novel-currently no widespread use in routine monitoring• Results are model specific!• No explicit upper size cut• Performance in smallest sizes is model specific
Size distribution
Impactors
16
www.dekati.com
www.ki.si
Cascade impactors are designed for a particle size related sampling of ambient and industrial aerosols. Weight or mass size distributions of nanoparticles are obtained.
Air inlet
Size distribution of nanoparticles
Differential mobility analyzer
Condensation particle chamberConcentrations: up to 1.107 NPs / cm3
Price: cca. 50.000 Eur
Particle Size Range:10 to 487nm
TSI model
Electrostatic Low Pressure Impactor
6 nm – 10.000 nmMax: 10 8 NPs / cm3Prize: 75.000 Eur
GRIMM SMPS (dr. Janja Vaupotič, JSI)
Measurements of aerosol concentration and their size distribution in the range 10 – 1100 nm were carried out at different locations. Scanning mobility particle sizer (SMPS+C; GRIMM Aerosol Technik) was used. The system consisted of the condensation particle counter (CPC) and electrostatic classifier (L-DMA), without the neutraliser.
Laboratory 1
open windowcleaning
Laboratory 2/Office – next to workroom
open window
Workshop (metallurgy)
end of working hoursstart of working hours
Parking place
evening morningend of working day
Background sample before vacuum system opened
Vacuum chamber door opened – first 6 minutes
Vacuum chamber door opened – after 9 minutes
Vacuum chamber door opened – after 30 minutes
Monitoring results in IonBond, UK
Monitoring at workplace
1. Personal sampling: Exposure integration or alarm for personal use. Daily to monthy analysis.
2. Mobile device: New operations, maintenance. Response time: 5 min.3. Work places: Monitoring tool for data collection and alarm. Response time: 5-
30 min.4. Efficiency of collective protective equipments. Qualification after new filter
installation.5-6: Drain: Environmental protection in the liquid drain.7-8: Extraction: Environmental protection in the air.9: External: 2 different needs:• Monthly survey of the impact of the factory on the environment (routine and
accidental situations)• Real time determination of the fluctuation of the external background noise in
order to correct inside measurements