Non-Destructive Imaging on Synthesised Nanoparticles.

Our recently developed non-destructive imaging technique was applied for the characterisation of nanoparticles synthesised by X-ray radiolysis and the sol-gel method. The interfacial conditions between the nanoparticles and the substrates were observed by subtracting images taken by scanning electron microscopy at controlled electron acceleration voltages to allow backscattered electrons to be generated predominantly below and above the interfaces. The interfacial adhesion was found to be dependent on the solution pH used for the particle synthesis or particle suspension preparation, proving the change in the particle formation/deposition processes with pH as anticipated and agreed with the prediction based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. We found that our imaging technique was useful for the characterisation of interfaces hidden by nanoparticles to reveal the formation/deposition mechanism and can be extended to the other types of interfaces.

Zeta potential of inorganic fine particle-Na-bentonite binder mixture systems.

The zeta potential of single and multi-inorganic fine particle mixtures (hematite and gangues, i.e., SiO2 + Al2 O3 ) with Na-bentonite was investigated to understand and properly control the mineral surface properties relevant to pelletization of low-grade fine iron ores. The zeta potential of hematite-bentonite mixture showed more negative charge up to 1 wt.% bentonite dosage and became constant. In the multiparticle mixture systems with bentonite, the SiO2 amount in the system controlled the changes in zeta potential due to its high negative charge (-54.9 mV at natural pH) and the bentonite attachment on its surface based on the electrostatic interaction while Al2 O3 had no effect due to its negligible surface charge (-1.6 mV at natural pH). This article reports the new insight into the characterization of surface chemistry of inorganic/mineral mixture systems to understand their surface charge properties in relation to fine mineral particle processing, and to show a direction toward the elucidation of particle dispersion/aggregation mechanism in complex ore systems aiming for their beneficiations.