A facile synthesis of hierarchically porous Cu-BTC for efficient removal of uranium(VI)
Authors: Duan, Chongxiong
Li, Jiexin
Yang, Pengfei
Ke, Guojun
Zhu, Chunxia
Zhang, Senlin
Journal: Journal of Radioanalytical and Nuclear Chemistry (2020)
Discipline: CHEMISTRY
Keywords: Metal-organic frameworks; uranium(VI) extraction; hierarchically porous; Cu-BTC; adsorption capacity

Abstract: Metal–organic frameworks (MOFs) are promising adsorbents for extraction of uranium(VI) due to their high surface area and abundant active site. However, the smaller pore size (&lt;\u20092&nbsp;nm) and harsh synthesis conditions (e.g., high temperature and pressure) severely hinder MOFs practical applications in some cases. Herein, we developed a simple and facile method to prepare hierarchically porous Cu-BTC that contained micropores, mesopores and macropores. The as-synthesized hierarchically porous Cu-BTC showed high uptake capacity (406.9&nbsp;mg&nbsp;g\u22121) and removal efficiency (99.7%) in the capture of uranium(VI) from an aqueous solution. Thermodynamics results indicate the spontaneous nature of uranium(VI) adsorption process onto hierarchically porous Cu-BTC. In addition, Langmuir isotherm and pseudo-second-order models were found to be more suitable in describing the adsorption process of uranium(VI) than those of Freundlich and pseudo-first-order models. These results indicate that hierarchically porous MOFs obtained from rapid room-temperature synthesis are promising adsorbents for the removal of uranium(VI) from aqueous solutions.

Retracted: No

PubPeer comments:
 Could the authors explain the relevance of these references?  However, conventional Cu-BTC belongs to microporous regime (pore size 2 nm), which has a smaller pore size significantly hindering the diffusion and mass transfer of guest molecules, regardless whether they are small molecules or large molecules [30u201333]. - [30]. Duan C, Zhang H, Li F, Xiao J, Luo S, Xi H (2018) Hierarchically porous metalu2013organic frameworks: rapid synthesis and enhanced gas storage. Soft Matter 14:9589u20139598 - [31]. Zhang D, Zhang H, Zhao S, Li Z, Hou S (2019) **Electrochemical impedance spectroscopy evaluation of corrosion protection of X65 carbon steel by halloysite nanotube-filled epoxy composite coatings in 3.5% NaCl solution**. Int J Electrochem Sci 14:4659u20134667 - [32]. Duan C, Cao Y, Hu L, Fu D, Ma J, Youngblood J (2019) **An efficient mechanochemical synthesis of alpha-aluminum hydride: synergistic effect of TiF3 on the crystallization rate and selective formation of alpha-aluminum hydride polymorph**. J Hazard Mater 373:141u2013151 - [33]. Yin K, Yang S, Dong X, Chu D, Gong X, Duan J-A (2019) **Femtosecond laser fabrication of shape-gradient platform: underwater bubbles continuous self-driven and unidirectional transportation**. Appl Surf Sci 471:999u20131004 These are wastewater-related references, but what do they have to do with uranium?  Direct discharge of uranium-containing wastewater without treatment will seriously threaten environmental ecology and human safety [2u20135]. - [3]. Yuan D, Zhang C, Tang S, Li X, Tang J, Rao Y, Wang Z, Zhang Q (2019) Enhancing CaO2 fenton-like process by Fe(II)-oxalic acid complexation for organic wastewater treatment. Water Res 163:114861 - [4]. Kang L, Du HL, Du X, Wang HT, Ma WL, Wang ML, Zhang FB (2018) Study on dye wastewater treatment of tunable conductivity solid-waste-based composite cementitious material catalyst. Desalination Water Treat 125:296u2013301 - [5]. Chen H, Zhang S, Zhao Z, Liu M, Zhang Q (2019) **Application of dopamine functional materials in water pollution control**. Prog Chem 31:571u2013579 , 
 References and this thesis are reported to prepare the relevant materials. Uranyl ions are a type of heavy metal ions, and the related removal of the metal ions in the report is of interest ,