速報
室温で調製したマグネタイトの界面動電特性
2000 年 116 巻 4 号 p. 297-301
詳細
2000 年 116 巻 4 号 p. 297-301
The electrokinetic characteristics were investigated in the solutions containing a supporting electrolyte for magnetite particles produced at ambient temperature and those of magnetite of commercial chemical reagent. For this purpose, the variation in the zeta (ζ)-potential with pH and the corresponding isoelectric point (i.e.p.) were determined for magnetite particles suspended in diluted solution of a supporting electrolyte, KNO3, K2SO4, Ca(NO3)2 or Al(NO3)3. The ζ-potential in KNO3 solution for the fine particles of magnetite produced at ambient temperature showed values similar to those of magnetite of chemical grade and for the both magnetite the isoelectric point was 6.5. In the presence of K2SO4, a shift of the i.e.p. toward pH 4 was attributed to the specific adsorption of SO42- . In an Al(NO3)3 solution, the i.e.p. of 9.35 is considered to be brought by presence of Al(OH)2+. Furthermore, in a solution containing calcium ion, the i.e.p. appeared in acidic environment probably due to non-equivalent exchange of proton on the particle surface with calcium ion in the solution. In all the cases under the conditions of this work the fine particles of magnetite prepared by ambient-temperature synthesis yields the almost same electrokinetic behavior as the chemical-grade magnetite which was treated at an elevated temperature.
