水相介质中纳米CeO_2的分散行为  

Dispersion Behaviors of CeO_2 Nanoparticles in Water Suspension

作　　者：宋晓岚[1] 邱冠周[1] 杨振华[1] 曲鹏[1] 

机构地区：[1]中南大学资源加工与生物工程学院,湖南长沙410083

出　　处：《稀有金属》2005年第2期167-172,共6页Chinese Journal of Rare Metals

基　　金：湖南省自然科学基金资助项目 (0 3JJY3 0 15 ) ;国家自然科学基金资助项目 (5 992 5 412 )

摘　　要：通过测定悬浮液体系润湿性、表面电性及分散性研究了纳米CeO2 在不同条件下水相介质中的分散行为。结果表明:纳米CeO2 在水相介质中的润湿与分散受体系pH值的影响很大,与Zeta电位有相当好的一致关系,其分散机理主要是双电层静电排斥作用;纳米CeO2 的等电点(pHPZC)为6.8左右;纳米CeO2 颗粒在酸性水介质中表面带正电,在碱性水介质中表面带负电,Zeta电位分别在pH值为4和11左右时较高,相应润湿性和分散性较好;随机械搅拌速率和时间的增加,纳米CeO2 的分散性增强;超声波对纳米CeO2 的分散作用明显优于机械搅拌,2 0kHz频率下超声波分散1min便能显著改善纳米CeO2 的分散状态;加入六偏磷酸钠(SHP)作为分散剂将改变纳米CeO2 颗粒表面电性,使其带负电,Zeta电位随SHP浓度增加而增大,起增强双电层的静电排斥作用;当SHP浓度达2 2 5mg·L- 1 时,Zeta电位趋于稳定,并使纳米CeO2 在广泛的pH值范围内获得较高的Zeta电位和很好的分散效果,从而降低了体系pH值的影响。Dispersion behaviors of CeO_2 nanoparticles under different conditions were studied in water suspension by investigating the wettability, Zeta potential and absorbency. The results indicate that the wettability and dispersion of CeO_2 nanoparticles are affected obviously by pH value of suspension and keep a coincident relation with Zeta potential. The dispersion mechanism is static repulsion interaction of double electrical layer. pH_ PZC of CeO_2 nanoparticles is about 6.8. The surfaces of CeO_2 nanoparticles are charged with positive electricity in acid water suspenson and with negative electricity in alkaline water suspenson, respectively. Zeta potential is higher when pH value is about 4 or 11, corresponding wettability and dispersion are better. The dispersion of CeO_2 nanoparticles enhances as velocity and time of mechanical stirring increase. The dispersion effect of ultrasonic wave on CeO_2 nanoparticles is markedly superior to mechanical stirring, and ultrasonic wave for 1 min at 20 kHz frequency can greatly improve dispersion state of CeO_2 nanoparticles. Addition of sodium hexametaphosphate(SPH) as the dispersant can make the surfaces of CeO_2 nanoparticles charged with negative electricity. The Zeta potential grows up evidently with increasing the SPH concentration, which plays the role of strengthening static repulsion interaction, and tends to be stable as the SPH concentration reaches 225 mg·L -1 . Simultaneously, CeO_2 nanoparticles obtain higher zeta potential and better dispersion within broad range of pH value, therefore, the influence of pH value in system is reduced.

关 键 词：纳米CeO2颗粒 水相介质 润湿 ZETA电位 分散 

分 类 号：TB383[一般工业技术—材料科学与工程]