Detection and potential impacts of nanomaterials released from building materials in the natural weathering environment

The use of (nano)-particles has increased over the past couple of decades, which includes incorporation into building materials such as lumber and cement. Since building materials are in the outdoor environment, incorporated (nano)-particles may be released into the environment and have unforeseen consequences. Outdoor weathering experiments were performed on two building materials, micronized copper azole (MCA) treated lumber and concrete with photoactive titanium incorporated with the cement, at five locations in the USA. MCA lumber released copper, but the amount and timing of release varied depending on the weathering climate. In humid areas, copper was released early in the first year of weathering. In hot and dry climates there was little initial release, but lumber cracking stimulated copper release during the second year, highlighting the significance of product aging. Laboratory leaching of MCA-sawdust demonstrated that 84% and 40% of the released copper passed through a 0.45µm filter and a 0.02µm filter respectively, suggesting released copper is a mixture of colloidal, nanoparticulate, and dissolved forms. As MCA wood is a source of toxic copper ions, Daphnia magna acute toxicity exposures were performed on leachates. Toxicity of the copper-containing leachate was equal to that of ionic copper added to leachate of non-MCA treated lumber. Dissolved organic carbon (DOC) co-leached from the MCA treated lumber was found to be approximately 40% as protective against copper toxicity as Suwanee River fulvic acid (SRFA), suggesting it had lower copper binding capacity than SRFA. Concrete containing nano-TiO2 (nTiO2) was exposed to outdoor weathering for ~2 years. Soluble elements (e.g. Ca) were released from the concrete at all locations, in keeping with the presence of these elements in the minerals contained in concrete. TiO2 was present at considerable levels in the weathering controls (1.5µg-30µg Ti deposited per month), likely due to an atmospheric dust background, which made it difficult to detect any released nTiO2. Total metal analysis, single particle ICP-MS, and particle imaging by electron microscopy did not present enough evidence to confirm significant TiO2 release from the concrete. Weathering release was difficult to detect in high background, low release scenarios (e.g. nTiO2 concrete), but low-background, high-release exposures (e.g. MCA lumber) allowed for straightforward detection and investigation of possible environmental impacts of nanomaterials

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Chemistry

Grantor dc:publisher

Colorado School of Mines. Arthur Lakes Library

Year dc:date.issued

2020

Author dc:creator

• Challis, Katie Elizabeth

Advisor dc:contributor.advisor

• Ranville, James F.

Committee members dc:contributor.committeemember

• Navarre-Sitchler, Alexis K.
• Meyer, Joseph S.
• Voelker, Bettina M.
• Munakata Marr, Junko

• nanomaterial release
• single particle ICPMS
• copper
• titanium dioxide nanoparticles
• nanoparticle

Statement dc:rights

• Copyright of the original work is retained by the author.

Language dc:language.iso

eng, English

Identifier

T 8969

OAI identifier oai:identifier

oai:repository.mines.edu:11124/174208