nanočástice

This work focuses on an investigation into the aggregation mechanisms of unstable, nanoscale particles in flowing groundwater. A study and a description of the process of aggregation help to simulate the transport of unstable undissolved nanoparticles. This could be useful when one needs to know how the nanoparticles behave in transit. In the following example a knowledge of this process is helpful. Some contaminants, such as halogenated hydrocarbons, are remediable by zero-valent iron nanoparticles. These are very unstable particles but still have a high potential in remediation field. Thanks to their (nano)size, they can migrate through the ground and are able to decontaminate wide areas. However, they aggregate into microsized entities and lose their migratory ability. Simulation of the transport of iron nanoparticles and their aggregation could be useful in predicting the success of decontamination interventions. The mathematical derivation of iron nanoparticle aggregation is so complex and difficult that this work is focused mainly on them. This work is mainly theoretical. First, an aggregation model is described. The model is based on aggregation due to the heat fluctuation of nanoparticles and due to their different velocities during sedimentation and drifting in groundwater. This model is then extended to include the impact of repulsive electrostatic and attractive magnetic forces that affect the rate of aggregation of magnetic nanoparticles with non-zero surface charge. The coefficients of aggregation are recalculated in order to compute the aggregation not only between single nanoparticles, but also between aggregates of nanoparticles (more simply called "particles"). A study of the possible aggregate structures was performed to be able to compute their mutual reactions. Extended coefficients of aggregation between particles were converted to coefficients of aggregation between ''sections'' of nanoparticles with similar size and properties. This enabled the simulation of aggregation in real time. The subsequent part of this work is dedicated to the computational aspects of aggregation in order to make the computation faster, but with a small error. At the end of the work, simulations of aggregation and transport of different types of nanoparticles are presented.

Investigation of Aggregation Models of Magnetic, Zero-valent Iron Nanoparticles