With the rapid development of nuclear power in my country,a large number of uranyl-containing waste liquids have been produced.There are many ways to deal with these waste liquids.It is an efficient and feasible method to extract uranyl from waste liquids by fiber.In this paper,three methods were used to modify wet spinning fibers(PAN-PAO fibers)to prepare modified polyacrylonitrile fibers with high adsorption properties for uranyl(Ⅵ)and the effects of p H,solid-liquid ratio,time,initial uranium concentration and temperature on the adsorption of uranyl by three modified fibers were investigated.The fibers before and after adsorption of uranyl were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),thermogravimetric(TGA),and X-ray photoelectron spectroscopy(XPS)techniques to explore the structure and adsorption mechanism of modified fibers.NH2OH·HCl and ethylenediamine were used to modify PAN-PAO fibers to prepare PAN-PAO-AO fibers and PAN-PAO-NH2 fibers.When the p H=5 and the fiber mass was 0.024 g,the adsorption capacities were 153.63 mg·g-1 and 151.54 mg·g-1,respectively.NH2OH·HCl was used to modify PAN-PAO-NH2 fibers to prepare PAN-PAO-NH2-AO fibers.When the solution p H=5 and the fiber mass was 0.016 g,the adsorption capacity was 235.78 mg·g-1.The adsorption kinetic models such as pseudo-first-order,pseudo-second-order and internal diffusion were used to analyze the adsorption process.The adsorption of uranyl by these three modified fibers was dominated by chemical reaction.The Langmuir and Freundlich isotherm model were used to fit the adsorption process,and it was found that PAN-PAO-AO fibers and PAN-PAO-NH2-AO fibers mainly adsorbed uranyl in a single layer,while the adsorption of uranyl by PAN-PAO-NH2fibers is mainly multi-molecular layer adsorption.Based on the analysis results,the adsorption of uranyl by fibers were through the chemical interaction of amine group and oxime group with uranyl group.The PAN-PAO fibers were modified to increase the density of functional groups on the fibers,thereby improving the adsorption performance of the fibers to uranyl(Ⅵ). |