Synthesis Of Functional Polyacrylonitrile Fibers And Their Selective Recognization And Adsorption For Metal Ions

In recent years, socio-economy has rapidly developed and people's living standard has gradually increased. While environmental issues are also increasingly prominent. Water pollution, especially heavy metal pollution, seriously affects the ecological balance and human health. Therefore, the identification and removal of heavy metal ions become the research focuses. The first part of this thesis is to immobilize benzothiazolium hemicyanine dye into ethylenediamine aminated polyacrylonitrile fiber to get a new colorimetric sensor PANBEF which can recognize Hg2+ with high selectivity and sensitivity. The second part of this thesis is to immobilize cysteine into triethylenetetramine aminated polyacrylonitrile fiber to efficiently remove heavy metal ions, especially silver ion, instead of favorable light metal ions in water.The first part of the thesis is based polyacrylonitrile fiber as the raw material. Polyacrylonitrile fiber reacted with the aqueous solution of ethylenediamine to get ethylenedimine aminated polyacrylonitrile fiber(PANEF). Then benzothiazolium hemicyanine dye was immobilized into PANEF to get a new colorimetric fiber(PANBEF). Then it was characterized by Fourier transform infrared(IR) spectra, elemental analysis(EA) data, X-ray powder diffraction(XRD)spectra and UV-vis absorption spectra. A series of tests about PANBEF were performed. When immersed in H2 O, Na+, Mg2+, Al3+, Ca2+, Cr3+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+, Hg2+ and Pb2+ solutions, the dark red PANBEF turns into orange in Hg2+ solution, but keeps its dark red color in H2 O and other metal ion solutions. When the concentration of Hg2+ is as low as 10-6 mol/L, the colorimetric fiber can still respond to Hg2+ with color change. It undergoes an obvious color change even in the Hg2+ solution containing excess ethylenediaminetetraacetic acid disodium salt. The response time of PANBEF to Hg2+ is less than 3 minutes and PANBEF can be used in the pH range of 3-11. All these show PANBEF has strong complexing ability with Hg2+. In addition, PANBEF can also adsorb Ni2+, Pb2+ and other toxic mental ions. So PANBEF can be not only used to selectively recognize mercury ion but also used as a removal agent for mercury and other toxic metal ions.The second part of the thesis is also based polyacrylonitrile fiber as the raw material. It reacted with the aqueous solution of triethylenetetramine to get triethylenetetramine aminated polyacrylonitrile fiber(PANTF). Then under alkaline condition, PANTF reacted with L-cysteine ethyl ester hydrochloride to get cysteine immobilized PANTF(PANCTF) which was characterized by IR spectra. The adsorption capacity of PANCTF toward different mental ions(Mg2+, Al3+, Ca2+, Cu2+, Zn2+, Ag+, Cd2+, Hg2+ and Pb2+) was measured. The results show that it has the best adsorption capacity for Ag+ and good adsorption capacity for other toxic heavy metal ions but almost no adsorption for Mg2+, Al3+ and Ca2+. And the fiber and polluted water can be separated by simple filtration. This is very favorable when PANCTF is used for wastewater treatment. Then the adsorption of PANCTF toward Ag+ was thoroughly studied. The effect of pH on the adsorption toward Ag+ was measured. And the adsorption kinetics and the adsorption thermodynamics of PANCTF toward Ag+ were studied.