Download Effect of Silver Nanoparticle Concentration and Size on E. coli

Silver research
• Vinka Oyanedel-Craver
• Assistant Professor
• University of Rhode Island
• Department of Civil and Environmental
Engineering
Silver nanoparticles
Disinfectant properties of
silver can be used to
add biocide properties
to different materials
and/or prevent biofilm
growth
Goal of study
• Inputs
• Silver nanoparticles (nAg) and silver ions
(Ag+)
• Amount of silver
• Water chemistry
• Materials (clay and burn-out)
• Outcomes
• Microbiological removal effectiveness
• Desorption of silver
• Biofilm development
Materials
Ceramic filters
•Clays: Indonesia, Tanzania,and Nicaragua
•Combustible material: sawdust, rice husk
•Silver: Colloidal silver (nAg) and silver nitrate
(Ag+)
Methods
•Silver release
•Bacteria removal
•Biofilm formation
Experimental Setup
a)
b)
c)
a) A schematic diagram of the tracer, bacteria and virus transport experiments
b) One-dimensional ceramic filter disc
c) Permeameter chamber
Experimental Setup
c)
•
•
A schematic diagram of the tracer, bacteria transport experiments
One-dimensional ceramic filter disc
Silver release
EPA silver standard in drinking water 100 microgram/L
nAg
Ag+
• Silver impregnated
disks have higher
bacterial removal
than controls
Control
range
• Performance of nAg
slightly superior
than Ag+
• Performance better
at higher
concentration
Control
range
• Sig. difference
between clays
• No difference in
Viable bacteria inside the ceramic
materials as function of silver
concentration and clay material
• Sig. difference
between clays
(Nicaragua)
• No difference in
water chemistries
Recommendations
• Ag+ not used above 0.03 mg/g
• Health consequences
• Loss of silver
• Increase nAg used to 640 mg/filter
• If hard water is used, increase more
Future Research
• Investigate
• Chlorine effect on sorption of silver
• Various methods of application
• Alternative disinfectants