Stochastic probability modeling to predict the environmental stability of nanoparticles in aqueous suspension

Abstract

The term "nanomaterial" describes a preparation in which the particle size is on the order of 10 to 100 nm in diameter. Such particles have the ability to form suspensions in fluid media such as air and water that can dramatically increase the environmental transport potential in comparision with like materials of larger particle sizes. Quantifying such transport requires an ability to predict the stability of such suspensions as to their tendency to aggregate or interact with other environmental constituents. In this paper, we present a method for predicting the magnitude and uncertainty associated with nanoparticle suspension stability. The critical buoyancy properties are predicted using the Boltzmann equation. The rates of aggregation are then predicted on the basis of molecular collision and adhesion coefficients. The progress of particle growth is simulated across all potential pathways probabalistically using the Gillespie model to characterize the uncertainty. Discussion is provided regarding potential environmental applications and further potential development in predicting particle behavior and effects on the environment.

Nanotechnology and in Situ Remediation: A Review of the Benefits and Potential Risks

“…EPA 2007). To be able to quantify the stability of nanoparticles in the environment, the stability of their suspensions and their tendency to aggregate and interact with other particles must first be determined (Mackay et al 2006). …”

Nanomaterials in the environment aquatic ecotoxicity tests of some nanomaterials

“…Colloidal particles in suspension move along the vertical as a result of gravitation and thermal motion. This results in a steady state in which the suspension concentration decreases exponentially from bottom to top according to the well-known Boltzmann equation [14,24]: The concentration at the bottom cannot exceed the density (concentration) of the solid phase C s . If C 0 reaches that value, a deposit starts to form so that the average concentration in suspension is limited to…”

“…By this mechanism, nanoparticles may be transported easily from water to sediment. Therefore, understanding the stability of a colloidal suspension may be of great importance in describing and predicting the environmental fate of nanoparticles in water [14]. Significant concentrations of nano‐sized material ought to be expected in natural water only if stabilizing factors are favorable [15].…”

Weight of Evidence approach for the relative hazard ranking of nanomaterials

“…Preliminary studies on ENM behaviour in the environment have highlighted that the stability and the aggregation kinetics of ENM can be useful descriptors to characterize exposure Elimelech 2006, 2007;Mackay et al 2006;Deguchi et al 2007). Since ENM have the tendency to aggregate in various solvents (e.g., water) and physiological environments (e.g., body fluids or media cell culture) and then to sediment under the action of gravity, assessing ENM propensity to form stable dispersion will be very important for the effects (Wick et al 2007).…”