Nanomaterials in complex environments : interactions affected by matrix composition, pH, natural organic matter, and bio- or geo-colloids

Sabaraya, Indu Venu
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Nanomaterials display unique properties as compared to their bulk counterparts due to their small size and high surface-area-to-volume ratio. These functional materials have emerged as an important constituent of many consumer products over recent decades. Engineered nanomaterials (ENMs) are being integrated into construction materials, biomedical devices and products, and energy -production and -storage materials, among many other applications. For ENMs to be effective in suspension-based products and devices and for understanding their fate and environmental effects upon release (during usage or at the end of the usable life), an assessment of ENM interaction with other particles of biological and geological origin in complex solution is essential. Aggregation, or lack of colloidal stability, of ENMs influences their functional efficacy as well as key physicochemical processes that ENMs might undergo in the environment, including sedimentation and dissolution. The functional promise and environmental fate of ENMs are strongly influenced by their inherent properties as well as the characteristics of the receiving medium in which they are applied or received. The receiving medium’s characteristics also can influence the pathways and mode of transformation of ENMs after environmental release. Although the nanomaterial literature is rich with studies of ENM interactions in simple and controlled media, there is a paucity of systematic studies evaluating the role of medium complexity on ENM interaction with bio- and geo-colloids. As described in the following goals, the work herein addresses this data gap by evaluating the interaction of nanomaterials in complex matrices: • Explore the relationship of ENM dispersibility within a simplified organic solvent mixture for a civil engineering application (i.e., asphalt matrix) with selected performance metric of the ENM-enabled asphalt binder. • Investigate the colloidal stability of next-generation two-dimensional (2D) ENMs in a heterogeneous particle system and in the presence of natural geo-colloids and organic matter to evaluate environmental fate of these ENMs. • Examine transformation pathways of 2D nanomaterials and their potential release from ENM-enabled devices in a simulated landfill leachate environment.