Purification of Silver Nanoparticles via Solvent Extraction at Different Temperatures

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Nopphon Weeranoppanant
Kanokporn Sritawong
Noppakao Pankaew


Synthesis of nanoparticles or nanocrystals often required excess amount of reducing agents for completion of reaction and stabilization of the nanoparticles. However, these agents remaining after the synthesis are considered impurities as they can affect subsequent processing steps such as shell growth and ligand exchanges. Therefore, it is important to remove these agents from the synthesized nanoparticles. Conventional purification methods are centrifugation, chromatography and electrophoresis, but they all have some limitations. In this work, we examine the possibility of using solvent extraction as a way to remove the impurities or excess ligands. The case study was the extraction of free oleylamine from synthesized silver nanoparticle solution (in hexane). Dimethyl formamide was used as extraction solvent. The extraction was considered as mild because the shapes and particle sizes of the silver nanoparticles were maintained even after the extraction, according to TEM images. The extraction was experimented at 30, 40 and 50 ºC. The samples were characterized with UV-Vis spectrometer and TGA. Increasing extraction temperature was found to be effective in promoting the extraction.

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