A highly efficient composite of Cu-BTC and g-C3N4 with bismuth doped for the adsorption of radioactive iodine

• Published in: Separation and purification technology Vol. 354; p. 128746
• Main Authors: Khan, Muhammad Musaa, Chen, Kai-Wei, Chen, Yi-Ting, Liu, Hong-Yu, Xia, Ming, Ni, Fei, Gong, Chun-Hui, Wang, Peng, Yang, Yi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.02.2025
• Subjects: Adsorption; Bismuth-doped; Chemical bonding; Cost effective; Environmental effects; Metal-organic framework; Radioactive iodine; Bismuth-doped; Adsorption; Radioactive iodine; Metal-organic framework; Cost effective; Chemical bonding; Environmental effects
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.128746

Synthesized composites of CNM-25 with different bismuth doping amounts for the adsorption of gaseous iodine as well as iodine in cyclohexane solution. [Display omitted] •Bismuth-doped Cu-BTC@g-C3N4 composites (x%Bi-CNM-25) were synthesized by in situ synthesis method.•Melamine sportive Cu-BTC composites capture iodine due to nitrate and CNH bonding both in gaseous and solution form.•The XPS spectrum confirms presence of polyiodides ions (I3-, I5-)on the surface of adsorbent.•Bismuth doped composites have low SBET (842.76 m2/g) but capturing high iodine, imply chemisorption and mechanism of adsorption was explained. Capturing radioactive iodine effectively is a top priority, but it remains a major challenge. In this manuscript, we report the synthesis of a bismuth-doped Cu-BTC [Cu3(BTC)2, BTC=1,3,5-benzenetricarboxylate] (%Bi/Cu-BTC) with a graphitic carbon nitride (g-C3N4) (Bi/Cu-BTC@g-C3N4) abbreviated as (x%Bi-CNM-25) via an in-situ, solvothermal method for the highly efficient absorption of iodine. The exceptional iodine capture performance of x%Bi-CNM-25 can be attributed to the strong chemical bonding between bismuth (Bi) and iodine (I2), the unsaturated metal, and the amine (−N) groups, highlighting the high effectiveness of this interaction. Furthermore, to evaluate Bi-CNM-25 as an effective sorbent, it was characterized via scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FITR), TGA/DTA, and X-ray powder diffraction (XRD). The BET-specific surface areas (SBET) were reported as 761.0782, 1,132.65, and 424.8015 m2/g for Cu-BTC, CNM-25, and 40 %Bi-CNM-25 and pore volume was 0.338, 0.493, and 0.215 cm3/g with (P/Po = 0.99) respectivily. Through experiments, its elemental composition and vibration before and after iodine adsorption were analyzed via EDS and X-ray photoelectron spectroscopy (XPS). During the capture process, I2 is reduced to I− by the intercalated Bi3+ via chemical adsorption. The maximum adsorption capacity of the Bi-CNM-25 composite exhibited for vapor iodine reached up to 588 mg/g in the form of an I2 molecule, which had a surface area, average pore diameter, and pore volume of 842.7342 m2/g, 4.54 nm, and 0.3900 cm3/g, respectively. The iodine absorption was up to 156.41 mg/g in kinetic and 169.32 mg/g for adsorption isotherm. The Langmuir isotherm and pseudo-second-order kinetic model followed the adsorption. To validate the results of model, statistical error validity models, such as Sum square error (SSE), Average relative error (ARE), Sum of absolute error (EABS), Hybrid fractional error function were applied. Moreover, the TGA/DTA results indicate that the adsorption of iodine by the 40 % Bi-CNM-25 was exothermic, spontaneous, and more stable, exhibiting thermal stability (320 °C). As per the previous different adsorbents for iodine adsorption, 40 %Bi-CNM-25 displayed iodine adsorption of approximately two times that of the commercial Ag-exchange zeolite X, and besides, x%Bi-CNM-25 is cost-effective. Therefore, the significant iodine capture by x%Bi-CNM-25 indicates that it is a capable adsorbent composite with great potential as a material for capturing and temporarily storing radioactive iodine.