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