Fabrication of porous cellulose acetate‑copper ferrocyanide adsorbent via thermally induced phase separation for highly efficient removal of cesium from wastewater

Efficient and stable adsorbents are crucial for addressing environmental pollution challenges, especially for the radioactive isotopes 137 Cs in aqueous environments. In this work, a novel composite adsorbent CA-CuPB was manufactured via the thermally induced phase separation (TIPS) method, aiming to remove Cs + from wastewater. CA-CuPB possesses a distinct bi-continuous and interconnected 3D porous network structure, which is characteristic of the Spinodal Decomposition (SD) mechanism in TIPS. Experiments show that the adsorbent CA-CuPB has excellent adsorption performance for Cs + , achieving a removal rate of 96% and an adsorption capacity of 198.06 mg/g in 60 min at pH =7. The adsorption behavior is well fitted by the pseudo-second-order model at 298.15, 308.15, 318.15 and 328.15 K and the Langmuir model ( R 2  = 0.9763, q max  = 282.53 mg/g), and the adsorption process is endothermic (∆ H 0  = 20.1784 kJ·mol −1 , ∆ S 0   =  101.4561 J·mol −1 ·K −1 , ∆ G 0  < 0 kJ·mol −1 ). Moreover, CA-CuPB showed high selectivity toward Cs + under the concomitant ions of Na + , K + , Ca 2+ and Mg 2+ , and excellent reusability with at least thirty consecutive adsorption-desorption cycles using ammonium chloride as the eluent. The adsorption mechanism of CA-CuPB toward Cs + is confirmed to be ion exchange by experimental data and DFT calculations. Further, fixed-bed adsorption experiments can achieve an adsorption deficiency of 85.42% when the column height is 30 cm, and the adsorption process is described by the Thomas and BDST models with high accuracy. Neither macroscopic swelling nor structural collapse was observed for the column in 45 days of soaking. Therefore, the new composite adsorbent CA-CuPB holds substantial potential for the rapid and efficient sequestration of Cs + from aqueous wastewater systems.