State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2017 Oct;24(30):23598-23606. doi: 10.1007/s11356-017-9989-y. Epub 2017 Aug 30.
The interaction between rice roots and Fe/Al oxide-coated quartz was investigated through zeta potential measurements and column leaching experiments in present study. The zeta potentials of rice roots, Fe/Al oxide-coated quartz, and the binary systems containing rice roots and Fe/Al oxide-coated quartz were measured by a specially constructed streaming potential apparatus. The interactions between rice roots and Fe/Al oxide-coated quartz particles were evaluated/deduced based on the differences of zeta potentials between the binary systems and the single system of rice roots. The zeta potentials of the binary systems moved in positive directions compared with that of rice roots, suggesting that there were overlapping of diffuse layers of electric double layers on positively charged Fe/Al oxide-coated quartz and negatively charged rice roots and neutralization of positive charge on Fe/Al oxide-coated quartz with negative charge on rice roots. The greater amount of positive charges on Al oxide led to the stronger interaction of Al oxide-coated quartz with rice roots and the more shift of zeta potential compared with Fe oxide. The overlapping of diffuse layers on Fe/Al oxide-coated quartz and rice roots was confirmed by column leaching experiments. The greater overlapping of diffuse layers on Al oxide and rice roots led to more simultaneous adsorptions of K and NO and greater reduction in leachate electric conductivity when the column containing Al oxide-coated quartz and rice roots was leached with KNO solution, compared with the columns containing rice roots and Fe oxide-coated quartz or quartz. When the KNO solution was replaced with deionized water to flush the columns, more K and NO were desorbed from the binary system containing Al oxide-coated quartz and rice roots than from other two binary systems, suggesting that the stronger electrostatic interaction between Al oxide and rice roots promoted the desorption of K and NO from the binary system and enhanced overlapping of diffuse layers on these oppositely charged surfaces compared with other two binary systems. In conclusion, the overlapping of diffuse layers occurred between positively charged Fe/Al oxides and rice roots, which led to neutralization of opposite charge and affected adsorption and desorption of ions onto and from the charged surfaces of Fe/Al oxides and rice roots.
本研究通过动电电位测量和柱浸出实验研究了水稻根与 Fe/Al 氧化物涂层石英之间的相互作用。使用专门设计的流动电势仪测量了水稻根、Fe/Al 氧化物涂层石英和包含水稻根和 Fe/Al 氧化物涂层石英的二元系统的动电电位。基于二元系统与水稻根单系统之间的动电电位差异，评估/推断了水稻根与 Fe/Al 氧化物涂层石英颗粒之间的相互作用。与水稻根相比，二元系统的动电电位向正方向移动，表明带正电荷的 Fe/Al 氧化物涂层石英和带负电荷的水稻根的扩散双电层重叠，并且带正电荷的 Fe/Al 氧化物上的正电荷被水稻根上的负电荷中和。Al 氧化物上带更多正电荷，导致 Al 氧化物涂层石英与水稻根的相互作用更强，动电电位的移动更大。通过柱浸出实验证实了 Fe/Al 氧化物涂层石英和水稻根上扩散层的重叠。Al 氧化物和水稻根上的扩散层重叠更多，导致当用 KNO3 溶液淋洗含有 Al 氧化物涂层石英和水稻根的柱时，K 和 NO 的同时吸附更多，浸出液电导率降低更大，与含有水稻根和 Fe 氧化物涂层石英或石英的柱相比。当用去离子水代替 KNO3 溶液冲洗柱子时，从含有 Al 氧化物涂层石英和水稻根的二元系统中解吸的 K 和 NO 比其他两个二元系统更多，这表明 Al 氧化物和水稻根之间更强的静电相互作用促进了 K 和 NO 从二元系统中的解吸，并增强了这些带相反电荷的表面上扩散层的重叠，与其他两个二元系统相比。总之，带正电荷的 Fe/Al 氧化物与水稻根之间发生了扩散层的重叠，导致相反电荷的中和，从而影响了离子在 Fe/Al 氧化物和水稻根的带电表面上的吸附和解吸。
