Synthesis of potassium metal ferrocyanide/Al-MCM-41 with fast and selective adsorption of cesium
2021
Dong, Chaochao | Deng, Xiaochuan | Guo, Xueqin | Wang, Bin | Ye, Xiushen | Fan, Jie | Zhu, Chaoliang | Fan, Faying | Qing, Binju
In this work, low-cost and non-toxic diatomite was used as the silicon source and aluminum source to synthesize Al doped MCM-41 (Al-MCM-41), and Cs⁺ adsorbents has been prepared by immobilizing the potassium metal ferrocyanide (KMeFC, Me = Cu²⁺, Ni²⁺, Zn²⁺, Co²⁺, and Fe³⁺) on Al-MCM-41. The adsorbents have high surface area from 471.7 to 685.8 m² g⁻¹, and their Cs⁺ adsorption performance has been detailed investigated. The max Cs⁺ adsorption capacity is 1.1602 mmol g⁻¹, 1.092 mmol g⁻¹, 0.8174 mmol g⁻¹, 0.6973 mmol g⁻¹, and 0.4541 mmol g⁻¹ for KZnFC/Al-MCM-41, KNiFC/Al-MCM-41, KCoFC/Al-MCM-41, KCuFC/Al-MCM-41, and KFeFC/Al-MCM-41, respectively. The KZnFC/Al-MCM-41 presents the highest adsorption capacity, and it can reach adsorption equilibrium with 10 min. The pH experiment results show the KZnFC/Al-MCM-41 can keep a higher adsorption capacity in pH range from 2 to 11. What more, the KZnFC/Al-MCM-41 present good adsorption selectivity against to K⁺, Na⁺, Ca²⁺, and Mg²⁺. The adsorption mechanism was also discussed, and the adsorption results show the adsorption process of Cs⁺ by KMeFC/Al-MCM-41 conforms to pseudo-second-order kinetics and Langmuir isotherm adsorption model, and the thermodynamic experiments confirmed the adsorption process of Cs⁺ by KMeFC/Al-MCM-41 are endothermic and spontaneous. The FT-IR, XRD, and XPS of KZnFC/Al-MCM-41 before and after adsorption of Cs⁺ inferred that the adsorption process of the adsorbents mainly completed by the exchange between Cs⁺ and K⁺. This work provide a novel strategy to synthesis of KZnFC/Al-MCM-41 in low-cost and green route, and the adsorbent as-synthesized in this work is an efficient candidate for removing or extracting Cs⁺ from radioactive wastewater and mineral resources.
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