Ordered mesoporous polymer–carbon composites containing amidoxime groups for uranium removal from aqueous solutions

By Zhibin Zhang, Zhimin Dong, Xiangxue Wang, Dai Ying, F. Niu, Xiaohong Cao, Youqun Wang, R. Hua, Yunhai Liu, Xiangke Wang. Chemical Engineering Journal, 2018

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Abstract Ordered mesoporous polymer-carbon composites containing amidoxime groups (AO-OMC) were successfully synthesized via in-situ polymerizing 2-Butenenitrile onto the external and internal surface of ordered mesoporous carbon (CMK-3). The characterization of small-angle X-ray diffraction, N2 adsorption–desorption isotherms and TEM confirmed that the polyacrylamidoxime was only coated on the mesopore walls with a thin layer rather than occupied the whole pores. The AO-OMC containing 16.8% polyacrylamidoxime (0.2AO-OMC) showed the highest adsorption capacity for U(VI) (322.6 mg·g−1 at pH = 5.0 and T = 298.15 K), which was significantly higher than CMK-3 (43.4 mg·g−1). XPS analysis suggested that the high adsorption capacity of 0.2AO-OMC was mainly attributed to the combination of U(VI) with abundant amidoxime groups via surface complexation and electrostatic interactions. The U(VI) selectivity was above 60% in a wide pH range from 3.0 to 5.0, which has not been reported to date, and reached the highest selectivity of 72.4% at pH = 4.0. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that uranium adsorption onto 0.2AO-OMC was an endothermic and spontaneous process, and the 0.2AO-OMC exhibited excellent reusability and structural stability without any significant changes in the adsorption capacity after ten cycles. This work highlighted the simple synthesis and application of AO-OMC as an efficient material for the high elimination of U(VI) from large volumes of aqueous solutions in environmental pollution cleanup.

Subfields: Industrial and Manufacturing Engineering, Inorganic Chemistry, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/03e778e82d943f0596e9c6003704fbb36516d0d6