2.3. Aggregation kinetics of AgNPs: model background
The evolution of the AgNPs absorption spectra with time provided
data to determine the aggregation kinetics of NPs. Therefore, the reduction
in A was monitored in order to follow the aggregation kinetics at
different NaCl concentrations and in natural fjord waters. The critical
coagulation concentrations (CCCs), were calculated when possible, as
they provide a simple stability limit of a NP suspension. The SPRB is
due to excitation of the conduction electrons in the particles. The changes
in the SPRB area reflect an overall aggregation process of the AgNPs
present in solutions. This probably includes not only non-aggregated
AgNPs, but also small clusters. The calculations were done measuring
the decrease of the SPRB area at the beginning of the aggregation