天然水的主要离子与水合氧化铁表面相互作用的实验研究

本文应用微电泳法研究天然水体的Na~+、K~+、Cl~-、Mg~(2+)、Ca~(2+)和SO_4~(2-)等主要离子与水合氧化铁表面的相互作用,分析了各离子浓度对水合氧化铁电泳淌度的影响和体系pH值的变化。结果表明,Na~+、K~+和Cl~-离子几乎不与水合氧化铁表面相互作用;Mg~(2+)、Ca~(2+)和SO_4~(2-)离子与水合氧化铁表面发生吸附作用,在pH为7.5左右的介质中,吸附能力的次序为Mg~(2+)>Ca~(2+)>SO_4~(2-)。

Studies on the interaction between major ions and the surface of hydrous iron oxide in natural waters

Interactions between the major ions in natural waters, such as Na~+, K~+, Cl~-, Mg~(2+), Ca~(2+), SO_4~(2-) etc, and the surface of hydrous iron oxide in simple electrolytic solution are studied with the method of micro-electrophoresis, while studing the effects of preparing conditions on the properties of hydrous iron oxide. The effects of various electrolytic concentrations on the electro-phoretic mobility and the changes of pH in medium are preliminarily discussed. Interactive abilities between Mg~(2+), Ca~(2+), SO_4~(2-) and hydrous iron oxide are compared, according to the changes in H~+ concentration in medium under the condition of identical concentration difference in various electrolytes. Results of the experiment in dicate that electrophoretic mobilities decrease with the increase of electrolytic concentrations. Monovalent ions, such as Na~+, K~+ and Cl~- hardly interacte with the surface of hydous iron oxide; bivalent ions, such as Mg~(2+), Ca~(2+) and SO_4~(2-) interact with the surface of hydrous iron oxide to induce exchange adsorption. The exchange abilities follow the order of Mg~(2+)>Ca~(2+)>SO_4~(2-) at circa pH 7.5.