Li Zeqiu, Yang Chenyang, Cho Kuk
Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro, 63beon-gil, Geumjeong-gu, Busan 46241, Republic of Korea.
Department of Environmental Engineering, Pusan National University, 2 Busandaehak-ro, 63beon-gil, Geumjeong-gu, Busan 46241, Republic of Korea.
J Hazard Mater. 2023 Jul 5;453:131385. doi: 10.1016/j.jhazmat.2023.131385. Epub 2023 Apr 7.
The presence of cesium ions (Cs) in radioactive wastewater has attracted considerable attention owing to their extreme toxic effects. Thus, there is an urgent need to develop adsorbents for Cs with high adsorption capacities (q). While phosphate-based adsorbents have advantages for their disposal, previous adsorbents have shown limited q because of their limited capacity for ion exchange, despite showing high theoretical q values. In this study, two dittmarite-type magnesium phosphates, KMgPO·HO (KMP) and NHMgPO·HO (NMP), were synthesized because of their ability to contain readily exchangeable cations in their interlayers. KMP and NMP demonstrated remarkable adsorption capacities for Cs (q = 630 mg g and q = 711 mg g), which were the highest among all reported adsorbents and are ∼84 % of their theoretical values. Their distribution coefficients in waters with high divalent ion concentrations were low, which limits their use for the adsorption of Cs from such environments. After adsorption, KMP and NMP were structurally transformed into struvite-type CsMgPO·6HO (CsMP), which has two different stacking structures, either cubic or hexagonal, depending on the pH of the solution. The high q values of KMP and NMP enable them to reduce the volume of radioactive waste for disposal.
放射性废水中铯离子（Cs）的存在因其极强的毒性作用而备受关注。因此，迫切需要开发具有高吸附容量（q）的铯吸附剂。虽然基于磷酸盐的吸附剂在处置方面具有优势，但先前的吸附剂由于离子交换能力有限，尽管理论q值较高，但其实际q值却有限。在本研究中，合成了两种迪特马利特型磷酸镁，KMgPO·HO（KMP）和NHMgPO·HO（NMP），因为它们的层间能够容纳易于交换的阳离子。KMP和NMP对Cs表现出显著的吸附容量（q = 630 mg g和q = 711 mg g），这是所有已报道吸附剂中最高的，约为其理论值的84%。它们在高浓度二价离子水中的分配系数较低，这限制了它们在此类环境中用于吸附Cs的应用。吸附后，KMP和NMP在结构上转变为鸟粪石型CsMgPO·6HO（CsMP），根据溶液的pH值，其具有立方或六方两种不同的堆积结构。KMP和NMP的高q值使其能够减少待处置放射性废物的体积。
