1. Tomsk Polytechnic University, Tomsk
KTH Royal Institute of Technology, Stockholm
RELEASE AND STABILITY OF METAL NANOPARTICLES IN SURFACE WATER:
EFFECTS OF PARTICLE LOADING
Elena Yunda
Undergraduate Student,
Scientific advisors: Asst. Prof. Anna Godymchuk (TPU)
Dr. Gunilla Herting (KTH)
Prof. Inger Odnevall Wallinder (KTH)
Tomsk- 2014

2. Outline Background Goal/Aim Materials and Methods
Results and Discussion
Conclusions 2

3. Growth of NPs production
Background
Growth of NPs production
Articles published on toxicity of NPs
Annual growth rate %
Number of articles
NMs
NMs toxicity
NMs ecotoxicity
[BBC Research]
[Kahru A., 2009]
Increasing number and diversity of nanoparticles sources
Nanoparticles characteristics identify nanoparticles behavior in liquid environment
Agglomeration
Metal release
Lack of data on physicochemical behavior of nanoparticles in environmental media
Sedimentation
Change of surface charge 3

4. Aim Nanoparticles Experiment Solution
Evaluate the effect of particle loading on nanoparticle stability and metal release in artificial surface water.
Nanoparticles
Experiment
100 nm
Exposure of NPs to solution
Time: 60 minutes
Temperature: 21°C
Loadings: 10 and 100 mg/L Al Ni Zn
S=15,5 m2/g
S=6,0 m2/g
S=13,6 m2/g
Centrifugation of suspensions
10 minutes, ~3000 r/min
Solution
Chemical composition (mg/L) and pH of OECD surface water
CaCl22H2O
MgSO47H2O
NaHCO3
KCl
29.38
12.33
6.48
0.58
pH = 6.0
Buffering: 170 L 0.95% H2SO4
Analysis of metal concentration in solution
GF-AAS
Evaluation of stability and average diameter of NPs
PCCS
* OECD - Organisation for Economic Co-operation and Development
* GF-AAS - Graphite furnace atomic absorption spectroscopy
* PCCS – Photon Cross-correlation Spectroscopy

5. Metal release and agglomeration of Al NPs
Metal released after
15 minutes of exposure
Loading:
10 …
100 mg/L
24 μg/L
115 μg/L
Low amounts of released aluminum in solution up to 1 h of exposure (<0.5% of the particle mass).
The surface of particles was more active in suspensions with lower loading.
1 min
dm = 950 nm
Aluminum NPs
100 mg/L
30 min
dm = 1230 nm
60 min
dm = 2700 nm
An increase of particles agglomeration with time.

6. Metal release and agglomeration of Zn and Ni NPs
Metal released from Zn and Ni nanoparticles
Agglomeration of Zn and Ni nanoparticles
60 min – all NPs settled
Decrease in concentration of particles in solution leads to an increase in solubility

7. Stability of NPs of Zn, Ni and Al in suspensions
10 mg/L Ni
10 mg/L Al
10 mg/L
Loading 10 mg/L was below the limits of the instrument under chosen experimental conditions Ni
100 mg/L Zn
100 mg/L Al
100 mg/L
Zn and Ni NPs settled after 60 minutes of exposure. Al NPs were relatively stable for 1 hour.

8. Conclusions
Nanoparticles characteristics (size, amount of metal released, stability) changed significantly with time (agglomeration + gradual dissolution + sedimentation).
Reducing the loading of nanoparticles in solution in 10 times increased the dissolution rate of Al in 2.5 times, Zn – in 3.1 times, Ni – in 2.2 times.
The loading of particles did not affect the kinetics of dissolution.
The influence of particles loading on the agglomeration process was not investigated due to the limits of the technique under chosen experimental conditions.

9. Acknowledgments Prof. Inger Odnevall Wallinder ingero@kth.se
Ass. prof. Anna Godymchuk
Dr. Gunilla Herting
PhD student
Sara Skoglund
This work was supported by the scholarship of the President of the Russian Federation for studying abroad and performed at the Division of Surface and Corrosion Science at KTH Royal Institute of Technology, Stockholm, Sweden.