Dispersion of ZnO Nano Particles in Aqueous Solutions Using Poly (vinylamine) as the Dispersant

• Main Authors: Nanik Hendrawati, 韓妮可
• Other Authors: Sheng-Shu Hou
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/89184870190874034926

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 97 === Dispersion of inorganic solid such as ZnO at nanoscale in aqueous suspension is one of the important issues in nanotechnological processes. The colloidal processing of particle has received much interest in many applications of industry such as coating, nanodevice, ceramic, paint, pigment, and pharmaceutical. The mechanism of polymeric stabilization on solid particles has been discussed in many publications. However, few researchers focused on colloidal stability of ZnO nanoparticles. In this work, aqueous suspensions of nano-ZnO powder with various pH values and amounts of dispersant are investigated. PVAm was selected as the dispersant for preparing a stable aqueous nano-ZnO suspension. The dispersion efficiency of polymer was studied by sedimentation settling test and reduction of absorbance measurement. The zeta potential measurement was used to elucidate the effect of polymeric addictive onto the surface of ZnO nanoparticles. In addition the surface charge measurement, the particle size distribution can give relatively real picture about dispersion state of solid particle. From this study we can gain better understanding of the dispersion mechanism of polymer to the ZnO nanoparticle. And we also know about the main factors influencing the effectiveness of polymeric dispersant.It was found that in the absence of poly (vinylamine); ZnO nanoparticles disperse in water completely precipitate instantly. Due to the lower zeta potential, the particles do not carry enough charge to repel each other. The electrostatic repulsion between particles is not sufficient to prevent nano-ZnO getting close and stick together because of the nature Van der Waals attraction and more likely to aggregate. By introduction of poly (vinylamine) into suspension, the stability of nano-ZnO increases significantly. It could be evidenced by the lower of ZnO nanopowder precipitation. In the presence of polymer, the surface charge of nano-ZnO shows the charge reversal and the value of zeta potential becomes further higher positive. The effectiveness of polymeric stabilization is closely related to the pH of suspension. It was found that the most stable suspension occurred at pH ranges 7 to 11.