纳米CeO_2的表面改性及其在水介质中的分散性能

Surface modification of CeO_2 nanoparticles and their dispersion properties in aqueous media

采用阴离子型表面活性剂十二烷基硫酸钠对纳米CeO2进行表面修饰,考察了表面改性工艺条件对纳米CeO2在水介质中粒度分布及Zeta电位的影响,确定了适宜的表面改性工艺条件:改性剂质量浓度60 g/L、改性温度25℃、改性时间4 h、搅拌速率150 r/min,pH 9～11。采用TEM、FT-IR、XRD对改性前后的纳米CeO2颗粒进行了表征,结果表明改性后纳米CeO2表面包裹了一层改性剂分子,颗粒在水介质中分散性良好,达到了单分散。此外,采用溶液共混法制备聚乙烯醇(PVA)/CeO2纳米复合膜材料,利用UV-Vis分光光度计表征了复合膜材料的光学性能,发现纳米复合膜具有良好的紫外屏蔽性能以及高的可见光透过率,在300～400 nm的近紫外光区,复合膜的紫外屏蔽率可达97%,添加5%纳米粒子的复合膜在650 nm处的可见光透过率比纯PVA膜降低了3%,保证了复合膜的透明度。

Sodium lauryl sulfate, an anionic surfactant, has been used to modify CeO2 nanoparticles. The influence of varying the processing conditions of surface modification on the secondary particle size distribution and zeta potential of CeO2 nanoparticles in aqueous media was investigated. Suitable conditions for the surface modification process were found to be as follows： a modifier concentration of 60 g/L, a modification temperature of 25℃ , a modification time of 4 h, stirring speed of 150 r/min and pH of 9 - 11. The CeO2 nanoparticles with and without modification were characterized by TEM, FT-IR and XRD. The results showed that the surfaces of modified nanoCeO2 particles were coated by a layer of surfactant. The nanoparticles were almost monodisperse in the aqueous media. In addition, polyvinyl alcohol （PVA）/CeO2 nanocomposite films were fabricated by a solution mixing method using the modified CeO2 particles. The optical properties of the nanocomposite films were investigated by UV-visible spectrophotometry. It was found that the nanocomposite films exhibited good UV-shielding properties and had high visible light transmittance ： In the near ultraviolet region of wavelength range 300 - 400 nm, the UV shielding ratio of the nanocomposite films reached 97% , whilst the visible light transmittance of the nanocomposite films with 5% of nanoparticles decreased by only 3% at 650 nm.