Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Cracow, Poland.
J Colloid Interface Sci. 2012 Nov 15;386(1):51-9. doi: 10.1016/j.jcis.2012.06.056. Epub 2012 Aug 2.
A stable suspension of α-Fe(2)O(3) (hematite) was synthesized according to the method of Matijevic and Scheiner by an acidic hydrolysis of ferric chloride. The average size of the particles was determined by dynamic light scattering (DLS) and atomic force microscopy (AFM) and was 22 nm. The electrophoretic mobility and zeta potential of particles were determined as a function of ionic strength and pH. The zeta potential of the hematite particles was positive for pH<8.9 (isoelectric point) and negative otherwise. Using the suspension, systematic studies of particle deposition kinetics on mica were carried out. The coverage of self-assembled particle monolayers was determined by AFM and SEM imaging. Particle deposition was diffusion controlled, with the initial rate proportional to the bulk concentration of particles. On the other hand, for long times, the saturation coverage was attained, increasing systematically with ionic strength. The deposition kinetic runs were adequately reflected by the random sequential adsorption (RSA) model. Additionally, particle desorption kinetics, from previously formed monolayers, were studied using the AFM and SEM methods. It was confirmed that hematite particle desorption was practically negligible within the time period of 60 h. Our experimental data proved, therefore, that it is feasible to produce uniform and stable hematite particle monolayers of desired coverage in self-assembly processes controlled by the bulk suspension concentration and the ionic strength.
根据 Matijevic 和 Scheiner 的方法，通过三氯化铁的酸性水解合成了α-Fe(2)O(3)（赤铁矿）的稳定悬浮液。通过动态光散射（DLS）和原子力显微镜（AFM）确定了颗粒的平均粒径，为 22nm。测定了颗粒的电泳迁移率和zeta 电位随离子强度和 pH 的变化。赤铁矿颗粒的 zeta 电位在 pH<8.9（等电点）时为正，否则为负。使用该悬浮液，系统研究了颗粒在云母上的沉积动力学。通过 AFM 和 SEM 成像确定自组装颗粒单层的覆盖率。颗粒沉积为扩散控制，初始速率与颗粒的体相浓度成正比。另一方面，对于长时间，达到了饱和覆盖率，并且随着离子强度的增加而系统地增加。沉积动力学运行由随机顺序吸附（RSA）模型充分反映。此外，还使用 AFM 和 SEM 方法研究了先前形成的单层上的颗粒解吸动力学。证实了在 60h 的时间内，赤铁矿颗粒的解吸实际上可以忽略不计。因此，我们的实验数据证明，在由体相悬浮液浓度和离子强度控制的自组装过程中，生产具有所需覆盖率的均匀和稳定的赤铁矿颗粒单层是可行的。
