河沙载镧复合材料去除水体中磷的研究

Removal of Phosphorus from Water by Lanthanum-coated-sand Composites

文章以廉价易得的河沙为载体,采用浸渍法制备得到载镧河沙复合材料,通过批量静态实验研究了载镧河沙对水体中磷酸盐的去除能力,并采用SEM、XRD、XPS进行了表征分析,探讨了去除机理。结果表明,随着载镧河沙投加量的增加,磷酸盐的去除率也随之增加;温度和水体中的共存阴离子对载镧河沙的除磷效果无明显影响;在酸性及中性条件下载镧河沙除磷效果优于碱性条件。载镧河沙对水中磷酸盐的去除过程符合Freundlich等温吸附模型和准二级动力学模型,属于非均相、化学吸附过程。XRD和XPS分析表明,镧以LaOOH的形态成功负载到河沙上,水体中磷酸根主要通过与其表面的羟基基团进行配位体交换作用而实现去除,主要产物为La_4H_3(PO_4)_5。在实际污水处理中,载镧河沙对磷酸盐表现出了高效的选择吸附性能,是一种很有应用前景的除磷剂。

Using sand as the carrier, the lanthanum-coated-sand composites were prepared by impregnation method to remove phosphate from aqueous solution. The samples were analyzed by SEM, XRD, XPS and other analytical methods to reveal the removal mechanism. The result showed that the phosphate removal efficiency increased with the increase in the dosage of lanthanum-coated-sand composites. Temperature and co-existing anions exhibited no significant effects on phosphate removal by the lanthanum-coated-sand composites. The phosphate removal efficiency in acidic and neutral conditions was better than that in alkaline conditions. The removal process of phosphate was in accordance with Freundlich isotherm model and quasi-second order kinetic model, which belongs to a heterogeneous surface and a chemical adsorption process. XRD and XPS analysis showed that lanthanum was successfully loaded into the river sand in the form of LaOOH and phosphate was mainly removed by the ligand exchange between the hydroxyl groups on the surface of the lanthanum-coated-sand composites, and the main product was La4H3(PO4)5. In the actual sewage treatment, the lanthanum-coated-sand composites for phosphate removal showed a high efficiency of selective adsorption performance, and it was a very promising adsorbent for phosphorus removal in practical application.