Behavior of TiO2 Released from Nano-TiO2-Containing Paint and Comparison to Pristine Nano-TiO2

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• 作者：Ahmed Al-Kattan ; Adrian Wichser ; Stefano Zuin ; Yadira Arroyo ; Luana Golanski ; Andrea Ulrich ; Bernd Nowack
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：June 17, 2014
• 年：2014
• 卷：48
• 期：12
• 页码：6710-6718
• 全文大小：434K
• 年卷期：v.48,no.12(June 17, 2014)
• ISSN：1520-5851

文摘

In the assessment of the fate and effects of engineered nanomaterials (ENM), the current focus is on studying the pristine, unaltered materials. However, ENM are incorporated into products and are released over the whole product life cycle, though mainly during the use and disposal phases. So far, released ENMs have only been characterized to a limited extent and almost nothing is known about the behavior of these materials under natural conditions. In this work we obtained material that was released from aged paint containing nano-TiO₂, characterized the particulate materials, and studied their colloidal stability in media with different pH and ionic composition. A stable suspension was obtained from aged paint powder by gentle shaking in water, producing a dilute suspension of 580 渭g/L TiO₂ with an average particle size of 200鈥?00 nm. Most particles in this suspension were small pieces of paint matrix that also contained nano-TiO₂. Some free nano-TiO₂ particles were observed by electron microscopy, but the majority was enclosed by the organic paint binder. The pristine nano-TiO₂ showed the expected colloidal behavior with increasing stability with increasing pH and strong agglomeration above the isoelectric point and settling in the presence of Ca. The released TiO₂ showed very small variations in particle size, 味 potential, and colloidal stability, even in the presence of 3 mM Ca. The results show that the behavior of released ENM may not necessarily be predicted by studying the pristine materials. Additionally, effect studies need to focus more on the particles that are actually released as we can expect that the toxic effect will also be markedly different between pristine and product released materials.