Preparation And Properties Of Adsorption-Seclective Micro-nano Fibers

With the development of science and technology,there is an increased demand for diversified and functional fibers,and nanofiber has been the focus of research in functional fibers for many years.Due to the spring up of nanomaterials,electrospinning technique,as an effective method to prepare nanofibers,has had rapid development spontaneously.Water pollution such as heavy metal and dye wastewater pollution has always been a significant environmental problem accompanied by the fast development of industrialization.The research and application of electrospinning nanofibers in the field of adsorption and separation are becoming richer and deeper.In this project,diacid and diamine monomers with benzene or pyridine were synthesized.Two kinds of macrocyclic compounds PBPM-1?PBPM-2,with certain size cavities,were prepared by coupling reaction.These two compounds were added to polystyrene solution of a specific concentration and then were prepared into blend-modified spinning fibers at the micro-nano size by electrospinning technology.The structure and surface topography of the modified fibers were characterized by fourier transform infrared spectroscopy(FT-TR),scanning electron microscope(SEM)and thermogravimetric analysis(TG).In order to study the adsorption properties of the two modified spinning fibers in metal ion wastewater and dye wastewater,the pH of the solution,the initial concentration of pollutants,adsorption kinetics and isothermal adsorption model were discussed in detail.Adsorption study showed that the average diameter of spinning fibers modified by PBPM-1?PBPM-2 were 439 nm and 710 nm,respectively.Rough wrinkles or microporous morphology can be seen in their surfaces.In the metal ions adsorption experiments,fibers modified by PBPM-1 and PBPM-2 both have selective adsorption performance for lead ions,with adsorption capacities of 60.5 mg/g and 46.8 mg/g,respectively.The adsorption was fast,and the adsorption equilibrium reached within 20-30 minutes.Meanwhile,pH is an important factor affecting the adsorption capacity.The adsorption capacity increased gradually with the gradual increase of pH.The adsorption process could be exp lained by the second-order kinetics as well as the Langmuir isothermal adsorption model.In the dyes adsorption experiments,fibers modified by PBPM-1 and PBPM-2 both have selective adsorption performance for malachite green,with adsorption capacities of 64.6 mg/g and 325.8 mg/g,respectively.The adsorption to dyes was slow unlike that of metal ions,and it take 3-7 hours to reach adsorption equilibrium.Similarly,pH is also an important factor affecting dye adsorption,and the adsorption efficiency was best when in nearly neutral conditions.The adsorption process of dyes could be explained by the Langmuir adsorption model.In terms of kinetics,the adsorption of dyes by PS/PBPM-1 and PS/PBPM-2 fibers could be explained by the pseudo-second-order kinetic and the pseudo-first-order kinetic,respectively.What is more,after adsorbing metal ions or dyes,the modified fibers can restore a certain adsorption capacity after being treated with EDTA or hydrochloric acid solution,which had a certain reuse value.