论文部分内容阅读
纳米粒子的聚集和再分散行为是影响纳米粒子在环境中归趋的重要因素.选取赤铁矿纳米粒子作为研究对象,用Zeta电位和粒径测定仪系统研究其在不同pH条件下的聚集和再分散过程.结果表明,当pH在7.0～8.7之间时,赤铁矿纳米粒子发生较快的聚集(如当pH为8.2时平均粒径在400s内由31nm增加到1400nm).当pH≤6.3时,赤铁矿纳米粒子几乎不发生聚集.不经老化聚集的赤铁矿纳米粒子均能发生再分散,但是再分散过程并不完全可逆,而是呈现一定的非线性.老化使得更多的赤铁矿纳米粒子发生不可逆的聚集,在等电点处老化后的样品不发生再分散.当pH为7.0和8.9时,老化的样品再分散后的平均粒径(约500nm)大于不老化的样品(约250nm).纳米粒子聚集-再分散过程的非线性对预测其在环境中的存在状态和生态效应带来了大的困难.
Aggregation and redispersion behavior of nanoparticles is an important factor that affects the fate of nanoparticles in the environment.Hematite nanoparticles were selected as the research object and the aggregation and redispersion behavior of nanoparticles were studied systematically with Zeta potential and particle size analyzer at different pH conditions Redispersion process.The results show that the hematite nanoparticles aggregate faster when the pH is between 7.0 and 8.7 (eg, the average particle size increases from 31 to 1400 nm in 400 s at pH 8.2) 6.3, the hematite nanoparticles almost did not aggregate, and the hematite nanoparticles aggregated without aging could be redispersed, but the redispersion process was not completely reversible, but showed some non-linearity. Of the hematite nanoparticles irreversibly aggregated, and the aged samples did not re-disperse at the isoelectric point.When the pH was 7.0 and 8.9, the average particle size after re-dispersion of aged samples (about 500nm) (About 250 nm) .The nonlinearity of nanoparticle aggregation-redispersion has brought great difficulties in predicting its existence and ecological effect in the environment.