镧负载D201树脂同步脱硝除磷的性能对比

Performance comparison of La-loaded D201 resins in the simultaneous removal of nitrate and phosphate

采用La^(3+)、La(OH)_(3)以及La_(2)(CO_(3))_(3)对D201树脂进行改性,并从吸附动力学、等温线、共存离子影响以及再生等方面系统地对比3种La负载树脂的同步脱硝除磷性能。扫描电镜及成分分析结果表明,D201表面能够负载不同形态的La,以La_(2)(CO_(3))_(3)形态负载时La含量最高。吸附数据表明,La_(2)(CO_(3))_(3)型D201树脂除磷效果优越,吸附容量高且受干扰离子影响小。经Na_(2)CO_(3)溶液再生5次后,各树脂均能保持良好的再生吸附效果,同步脱硝除磷性能稳定。树脂中季铵官能团(-R^(4)N^(+))对硝酸根选择性较高,使得硝氮吸附受共存离子的影响较弱;磷酸根吸附归因于与-R^(4)N^(+)静电作用及与负载的各形态La形成沉淀、发生配体交换等,受体系pH值变化较为敏感,弱碱性条件可促进吸附。

In this study,different forms of lanthanum(La),including La^(3+),La(OH)_(3) and La_(2)(CO_(3))_(3),were employed to modify D201 resin.The obtained resins were critically examined and compared with each other on the simultaneous removal characteristics of nitrate and phosphate,from the perspective of kinetics,isotherms,influence of coexisting ions,and regeneration.SEM images and component analysis revealed that different species of La were evidently loaded on the D201 surface and the highest La content was obtained on the La_(2)(CO_(3))_(3)-loaded D201 resin.In addition,the La_(2)(CO_(3))_(3)-loaded D201 resin maintained favorable dephosphorization performance against coexisting ions.Notably,the original and La-loaded D201 resins could retain the adsorption efficiency after being regenerated by Na_(2)CO_(3)5 times,an indication of stable denitration and dephosphorization performance.R^(4)N^(+)groups preferentially captured nitrate so that there was a negligible influence of coexisting ions on nitrate uptake.The phosphate adsorption was attributed to electrostatic interactions with R^(4)N^(+)groups and chemical precipitation or ligand exchange with the loaded La.Moreover,it was more sensitive to the solution pH change,as supported by the improvement under weak alkaline conditions.