摘要:
以Cd2+离子和罗丹明B (RhB)分子共存的废水溶液为研究对象，提出了一步光催化净化思路：即首先向溶液中加入磷酸盐使Cd2+固化形成Cd5H2(PO)4•4H2O沉淀，再利用Cd5H2(PO)4•4H2O在紫外光照射下产生的活性物种原位氧化分解RhB，实现了溶液中Cd2+和RhB同时去除的目的。研究了镉盐种类、磷酸盐种类以及光照三个因素对Cd2+-RhB溶液处理的影响，结果发现，Cd(CH3COO)2、CdSO4和Cd(NO3)2都能被磷酸盐固化形成Cd5H2(PO)4•4H2O沉淀，在紫外光照射下，降解RhB的顺序为：Cd(NO3)2 > CdSO4 > Cd(CH3COO)2；Na3PO4、Na2HPO4和NaH2PO4都能与镉离子反应生成Cd5H2(PO)4•4H2O沉淀，在紫外光照射下，降解RhB的顺序为：Na3PO4 > NaH2PO4 > Na2HPO4；而没有紫外光和催化剂的条件下，RhB分子不会降解。
Abstract:
This work proposes a one-pot photocatalytic method to purify wastewater containing Cd2+ and RhB dye. In briefly, by addition of phosphates to immobilize cadmium ions, Cd5H2(PO4)4∙4H2O pre-cipitates were initially formed. The Cd5H2(PO4)4•4H2O could be excited by UV to generate active species and then degraded RhB in situ, addressing the simultaneous removal of Cd2+ and RhB solu-tion. The effect of cadmium ion species, phosphate type and light irradiation on the structure of the formed products and the removal performance for Cd2+-RhB solution was investigated. The results showed that all cadmium ions such as Cd(CH3COO)2, CdSO4 and Cd(NO3)2 could be immobilized to form Cd5H2(PO)4∙4H2O, which indicated the activity order for RhB as Cd(NO3)2 > CdSO4 > Cd(CH3COO)2. Three phosphates like Na3PO4, Na2HPO4 and NaH2PO4 could immobilize cadmium ions to obtain Cd5H2(PO)4∙4H2O that possessed the activity order for RhB as Na3PO4 > NaH2PO4 > Na2HPO4. In the absence of UV light and photocatalyst, RhB could not be degraded.