Nanoparticle silver released into water from commercially available sock fabrics

Area of Science:

• Environmental Science
• Materials Science
• Nanotechnology

Background:

• Nanosilver (n-Ag) is used in clothing for antimicrobial properties.
• Environmental impacts and release of n-Ag from commercial products are largely unknown.
• Assessing environmental risks of nanotechnology requires understanding nanomaterial release from consumer goods.

Purpose of the Study:

• Investigate silver release from commercial socks into water.
• Determine the form (colloidal vs. ionic) and quantity of silver released.
• Analyze the fate of released silver in wastewater treatment plants (WWTPs).

Main Methods:

• Analysis of silver content in six types of socks.
• Leaching experiments using distilled water.
• Microscopy for silver particle size determination.
• Physical separation and ion-selective electrode (ISE) analysis for silver form.
• WWTP biomass adsorption experiments to model silver fate.

Main Results:

• Socks contained up to 1360 µg-Ag/g, leaching up to 650 µg silver per 500 mL.
• Silver particles ranged from 10 to 500 nm; both colloidal and ionic silver were detected.
• Leaching rates varied among sock types, suggesting manufacturing process influence.
• A model predicted WWTPs can treat high silver influent concentrations.
• High silver concentrations may restrict biosolids disposal as fertilizer.

Conclusions:

• Commercial socks release significant amounts of nanosilver into water.
• The manufacturing process influences the rate of silver leaching.
• While WWTPs can manage leached silver, its accumulation poses a challenge for biosolids reuse.