Stability Study of Nano-Silver Particles Dispersed in Various Solvents by Turbiscan Lab Optical Analyzer
XIA Zhao-hui, Lü Li-yun, WANG Hong*
Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072，China
Abstract：Nano-silver particles were synthesized through chemical reduction method, using silver nitrate, m-dihydroxybenzene and polyvinylpyrrolidone as silver source, reduction agent and protective agent respectively; and redundant reactants were removed through centrifugation and washing operation. Then different nano-silver colloids were acquired by dispersing the nano-silver particles in water, ethanol and ethylene glycol respectively through ultrasonic dispersion. For comparison, the nano-silver particles mass fraction of all the colloids was 0.2 Wt% during the research. Nano-silver particles were characterized by laser particle size analyzer, transmission electron microscopy (TEM) and scanning electron microscopy (SEM); and the concentration of nano-silver colloids was confirmed through synchronized thermal analyzer (STA). The size distribution result of laser particle size analyzer showed that nano-silver particles were about 100 nm and had uniform size distribution. The images of TEM and SEM showed that the size of nano-silver particles was in nanoscale as well. To evaluate the dispersion stabilities of different nano-silver colloids, Turbiscan optical analyzer which was based on multiple light scattering analysis had been employed in the research; and the principle factors leading to instabilities of nano-silver colloids were also discussed. Results showed that particle size variation and particle migration were major factors which affected the dispersion stabilities of nano-silver colloids. For the nano-silver colloid dispersed in water phase, the backscattering light signal in middle of the sample cell stayed unchanged with time while the backscattering light signals at top and bottom of the sample cell showed dramatic variation during the measurement, which indicated that particle migration was the main reason why the nano-silver colloids was unstable. But for the nano-silver colloids dispersed in ethanol and ethylene glycol phase, the backscattering light signals in bottom, middle and top of the sample cell presented obvious variation at the end of the tests, which certificated that both particle size variation and particle migration affected the stabilities of nano-silver colloids. At last, by comparing the Turbiscan Stability Index (TSI) of three different nano-silver colloids, the stabilities of the systems were outlined by a descending order: ethylene glycol, water and ethanol.
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