Abstract
Clay suspensions are of great importance in many industrial applications for the advantages of their gelation ability. The synthetic hectorite-type clays such as Laponite XLG are known to form clear dispersions since they comprise high-purity, very small-size crystallites; they are particularly suited for applications involving light. The clay suspension was used as a new application for the matrix of the preparation and the aggregation control of nanoparticles. In this paper, we studied the effect of salt concentration in the solution on the aggregation control of gold nanoparticles. The gold nanoparticles were prepared in an aqueous solution with Laponite XLG clay by the reducing method using sodium borohydride at 298 K. When clay concentration was 0.5 wt%, which was gel state, the aggregation of gold nanoparticles did not observed even in 30 days after the preparation. In addition, the clay gel prevented the aggregation of the gold nanoparticles, even if the salt was added further. The aggregation of the gold nanoparticles, on the other hand, occurred with the elapsed time in 0.12 wt% clay suspension, where clay was sol state. However, if the salt was added in the dispersion of the gold nanoparticles with 0.12 wt% clay, clay particles aggregated and then it prevented the aggregation of the gold nanoparticles.
