Studies on the Preparation of Silver Nanoparticles by Solvent Extractive Reduction Method

• Main Author: 洪啟豪
• Other Authors: Teh-Hua Tsai
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/89734257076541059850

碩士 === 國立臺北科技大學 === 化學工程系碩士班 === 90 === In this thesis, the silver nanoparticles were prepared by solvent extractive reduction at 25℃. The extraction equilibria of silver between extractant / toluene solution and aqueous solution are studied first. It is attempted to investigate the effect of products composition and the influence of various preparation conditions on products. The polystyrene containing silver particles were prepared in this method next, and the influence of silver nanoparticles on the properties of polystyrene were investigated. The extraction equilibria of silver from sulfate solutions with di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant are studied first. The experimental data indicates the distribution ratios for the extraction of silver increase with increasing pH value in the aqueous phase. By graphical treatment, the compositions of silver-D2EHPA complex in the organic phase are AgA(HA)and AgA(HA)2, and the equilibrium constants are 0.00235 and 0.00612 (kmol/m3)-1/2, respectively. The average diameters of the silver nanoparticles obtained in this study were in the range of 4.2 to 6.7 nm. Stabilizer were tightly adsorbed on the particle surface and formed a self assembly monolayer. After evaporating the solvent, they can be recrystallized from the parent solution and have a nice dispersity which is stable for months, which indicates that the good protective effect of stabilizer for nanoparticles. By the analyses of TEM, electron diffraction pattern, FE-SEM, EDX, FT-IR, X-ray diffraction and UV-VIS, the product has been confirmed to be the pure silver nanoparticles with a face-centered cubic (f.c.c.) structure. Stabilizer quantity is not a major factor which influences the average diameters of the product , but it will influence the yield. With the increase of stabilizer content, the yield is increased. With the increase of preserve time, the silver nanoparticles had a smaller size distribution. It had a smaller diameter at higher silver nitrate concentration. The polystyrene containing silver nanoparticles have a nice dispersity. When more silver nanoparticles put in polystyrene, the thermal stability of polystyrene containing silver nanoparticles was higher, the Tg of the polystyrene was higher too. Because nanoparticles are not enough or are covered in PS, the influence with electrical conductivity of PS was not obvious.