Preparation And Application Of Novel Chelating Fiber Based On Polyacrylonitrile

With the rapid development of industry, the let of pollutions has been endangering great engenderment for environment and human health, and the heavy metals are particularly serious. Therefore, the preparation of efficient sorbents that can be used to treat heavy metal ions in waste water has important value. As one type of high effective sorbents, the chelating fibers have been now widely developed.Firstly, in this dissertation a series of novel chelating fiber based on polyacrylonitrile fiber was prepared through amination and carboxymethylation. The better experimental conditions were determined by studying the influences of reaction temperature, reaction time and concentration of reactant and so on. The main experimental results include that: (1) the amination reaction becomes more and more difficult with increasing of molecular chain length; (2) both primary amine and secondary amine in polyamines can react with polyacrylonitrile fiber; (3) the carboxymethylation reaction is mainly influenced by concentration of reactant. The structures of the chelating fiber were characterized by the means of IR spectrum, SEM and X-ray diffraction, and the mechanism of the functionalization reaction was investigated.Secondly, the adsorptive capacity for Cd²⁺ of this chelating fiber was determined through studying the effect of pH value and adsorption time on adsorbance; the adsorptive capacity for Cd²⁺ under lower concentration was determined and the repetitive-use of this fiber was studied. Moreover, the adsorptive capacity for Cd²⁺,Hg²⁺,Pb²⁺,Ni²⁺,Cu²⁺,Ag+,Mg²⁺ in simulant waste water and Cd,Hg,Pb,Be in actual sewage were determined, and the adsorption mechanism was also discussed. The main results include that: (1) the adsorptive speed is fast and the adsorptive capacity is high for Cd²⁺ of this fiber. The adsorption can achieve saturation in 15 minutes and the saturated adsorbance is 1.337 mmol/g; (2) the saturated adsorbance for Cd²⁺ also can achieve 0.712 mmol/g after this fiber has been used for 10 times; (3) the adsorption result for Cd²⁺ in simulant waste water is excellent and the concentration of Cd²⁺ is reduced from 0.5 ppm to less than 0.01 ppm in 24 h; the adsorption result for other metal ions is also good; (4) the adsorption result for cadmium in actual sewage is also excellent and the concentration of cadmium is reduced from 0.38 ppm to less than 0.01 ppm in 24 h.