Stability and sedimentation of silver nanoparticles in the presence of monovalent, divalent and trivalent electrolyte solutions

摘要

The present study seeks to elucidate the effect of different electrolytes on the stability of citratecoated silver nanoparticles synthesized by the reduction of the Ag(NH_3)~+_2 complex via Tollens'method. Time-resolved dynamic light scattering technique was used to measure the aggregation behavior of the nanoparticles over a range of electrolyte (NaCl, CaCl_2, and AlCl_3) concentrations. From the aggregation kinetic data, the critical coagulation concentration values were calculated as 0.11, 1.7 × 10~(-3), and 5.06 × 10~(-6)M for NaCl, CaCl_2, and AlCl_3, respectively. Supernatant of the nanoparticle suspension in presence of the three electrolytes was collected and measured using inductively coupled plasma mass spectrometry to quantify the sedimentation. It was found that the silver nanoparticle aggregates settled rapidly in the slow aggregation and fast aggregation regimes. Their sedimentation followed a nanoparticle size-dependent manner.