Surface-charging and particles aggregation behavior of ascharite
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College of Resources and Civil Engineering, Northeastern University
School of Earth Science and Resources, Chang’an University
zhihang Li   

College of Resources and Civil Engineering, Northeastern University
Publication date: 2019-06-03
Physicochem. Probl. Miner. Process. 2019;55(4):991–1001
Surface charging and particles aggregation ascharite are investigated through Zeta potential measurement, XPS analysis, SEM analysis and dissolution experiments. The results show that more Mg2+ are removed from ascharite surface after dissolution, which confirms that incongruent dissolution of ions in the case of certain ionic substances like rmagnesium ions, hydroxyl groups and borate ions can lead to a net charge on surface. Isomorphous substitution of Fe3+ for Mg2+ is also regarded as one factor that causes surface charging behavior, which is in consistent with the experimental data. The dissolution process is analyzed to show more details about the dissolution reactions. The disparity in the bonding energy of B–O and Mg–OH surface groups and the difference in free energy of hydration of surface groups are considered to be the basic reason that lead to incongruent dissolution. Eventually, the effect of surface potential on particles aggregation is analyzed by DLVO theory, indicating that dissolution of ascharite has a detrimental effect on particles dispersion.