Zeta potential at the root surfaces of rice characterized by streaming potential measurements
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Our objective was to determine the in situ zeta potential at the root surfaces of rice.
A streaming potential apparatus made in our laboratory was used to measure zeta potential at the root surfaces.
Zeta potential at the root surfaces could be calculated from streaming potential measured by the apparatus, and the measurements of streaming potential had good stability, reproducibility and accuracy. Ionic strength, electrolyte type, pH influenced the zeta potentials, with being consistent with theoretical calculations. The absolute value of the zeta potential at the root surfaces decreased with increasing ionic strength due to compression of diffuse layer of the electric double layer. Cations had much greater impact on zeta potential than anions due to the electrostatic attraction of cations by the negatively charged root surfaces and electrostatic repulsion of anions. The effects of different cations on the zeta potential followed the order: Al3+ > H+ > Cu2+ > Mg2+ ≈ Ca2+ > K+ ≈ Na+. The zeta potential of root surfaces became more negative with increasing pH due to deprotonation of functional groups on roots.
Streaming potential measurement is a novel method that can be used to calculate zeta potential of root surfaces.
KeywordsRice root surfaces Streaming potential Zeta potential Surface charge
This study was supported by the National Natural Science Foundation of China (41230855) and the Knowledge Innovation Program Foundation of the Chinese Academy of Sciences (KZCX2-EW-405).
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