Facile construction of a core-shell structured metal-organic frameworks nanofiber membrane for removing Co(II) from simulated radioactive wastewater

Abstract

A novel core–shell structured composite of UiO-66-Tu/PAN nanofiber membranes (NFMs) functionalized with thiourea (Tu) was developed for the efficient separation of Co(II) from simulated radioactive wastewater. Various analytical techniques were employed to characterize the structure and properties of the NFMs. The filtration performance, flux, and hydrophilicity of the membrane were evaluated using a membrane flux tester and contact angle (CA) measurements, respectively. The adsorption performance of UiO-66-Tu/PAN for Co(II) was investigated through batch adsorption experiments. The results indicate that at a UiO-66-Tu/PAN content of 7 %, the UiO-66-Tu/PAN NFMs exhibit better hydrophilicity (CA of 37.8°) and a higher cobalt ion retention rate (77.41 %). Under optimal conditions, the theoretical maximum adsorption capacity for cobalt ions is 51.2 mg/g. X-ray photoelectron spectroscopy (XPS) analysis was utilized to clarify the adsorption mechanism of Co(II) by the 7 %UiO-66-Tu/PAN composite, showing a coordination mechanism that involves the participation of oxygen, nitrogen, and sulfur atoms in the ligand. In addition, the material also demonstrates excellent radiation stability (50–100 kGy). It should be pointed out that this is the first time that metal–organic frameworks (MOFs) core–shell nanofibers membranes have been used for cobalt ion separation. The development of this new material effectively addresses the challenges associated with using MOFs as powdered adsorbents, achieving efficient purification of wastewater and providing important engineering significance for the treatment and disposal of trace amounts of ⁶⁰Co radioactive wastewater.