磁铁矿和水铁矿对高盐水中磷酸盐的吸附特性及机理

Characteristics and mechanism of phosphate adsorption from high-salinity water onto magnetite and ferrihydrite

通过吸附动力学和吸附等温模型研究了磁铁矿和水铁矿对高盐水中磷酸盐的吸附特性及机理,考察了钙镁离子的存在对吸附效果的影响。实验结果表明:磁铁矿和水铁矿对高盐水中磷酸盐的吸附动力学过程符合Elovich动力学模型;磁铁矿对磷酸盐的吸附平衡数据更适合采用Freundlich模型进行拟合;水铁矿对高盐水中磷酸盐的等温吸附行为可以用Langmuir和Freundlich模型描述。钙离子会促进磁铁矿和水铁矿对高盐水中磷酸盐的吸附。镁离子对磁铁矿和水铁矿吸附高盐水中磷酸盐的影响与是否存在钙离子密切相关。CaHPO40/MgHPO40与羟基基团之间的配位体交换反应和以磷酸盐桥连的三元配合物的形成对于磁铁矿和水铁矿吸附含钙镁离子的高盐水中的磷酸盐起重要作用。

The characteristics and mechanism of phosphate adsorption from high-salinity water onto magnetite and ferrihydrite were studied using adsorption kinetics and adsorption isothermal model.The effects of calcium and magnesium ions on the adsorption were investigated.The experimental results show that:The adsorption processes of phosphate from high-salinity water onto magnetite and ferrihydrite are in accordance with the Elovich kinetic model;The adsorption equilibrium data of phosphate onto magnetite is more suitable for fitting using the Freundlich model;The isothermal adsorption behavior of phosphate onto ferrihydrite can be described using Langmuir and Freundlich models.Calcium ions can promote the adsorption of phosphate onto magnetite and ferrihydrite.The effect of magnesium ion on the adsorption of phosphate onto magnetite and ferrihydrite is closely related to the presence of calcium ions.The coordination exchange reaction between CaHPO40/MgHPO40 and hydroxyl groups and the generation of phosphatebridged iron-phosphate-calcium complex play important roles in the adsorption of phosphate onto magnetite and ferrihydrite from high-salinity water containing calcium and magnesium ions.