Electrospun Composite Nanofibrous Films With Adsorption, Separation And Detection Abilities For Heavy Metal Ions

With the development of industry, water pollution problems are attracting more and more attentions, especially the heavy-metal-ion pollution. The heavy metal ions can be transferred and concentrated inside the human body through food chain. However, they cannot be metabolized. It may cause many diseases. Therefore, it is an urgent problem to develop strategies to adsorb, separate and detect the heavy metal ions in water.Electrospinning is a rapid and highly efficient method to fabricate nanofibrous films. Electrospun membranes have the advantages of high-ratio surface area and porosity that they are very suitable for water treatment. Hyperbranched poly(amide amine)s (HPAMAMs) are abundant of amine groups. They can chelate with the heavy metal ions. Moreover, the HPAMAMs have excellent fluorescence properties. Their fluorescent intensity is stimuli-responsive to the heavy metal ions. It was therefore speculated that through combining the electrospun membranes and the HPAMAM, nanocomposite membranes with adsorbing, separation and detective ability could be fabricated. In this thesis, we have done some research on the functional membrane composed from HPAMAM and electrospun membranes. The results were listed as following:1? PA-6 and PMMA nanofibrous films were prepared separately through electrospinning. The HPAMAM molecules were then deposited onto the surface of the nanofibers by surface adsorption and crosslinking. Multifunctional composite membranes, in which the electrospun fabric membranes functioned as the supporting skeleton and the surface coated HPAMAM as the shell.2? PA-6/HPAMAM nanofibrous films had excellent capability to absorb the Co2+ ions from the water. When pH = 6, Co(Co2+)= 30 mg/L, and using a 0.5 g/L nanofibrous film, the maximum adsorption capacity of composite films was 42.32 mg/g. The isothermal adsorption behavior agreed with the Langmuir adsorption model. The dynamic adsorption behavior agreed with the pseudo-second order kinetic model.3? The fluorescent intensity of PMMA/HPAMAM nanofibrous films was stimuli-responsive to the heavy metal ions. The PMMA/HPAMAM nanofibrous films were immersed into the Co2+, Ni2+, Hg2+, Zn2+ and the other metal ion solutions. Subsequently, they were taken out and quickly dried. It was found that fluorescent intensity of the PMMA/HPAMAM nanofibrous films decreased at different degrees.