| In recent years, heavy metals are more widely used in global industrial innovations and socio-economic developments. Through a variety of ways, heavy metals have been enriched into human body indirectly or directly, which has become serious threat to human life and health. Therefore, it is a major research topic of safety problems which caused by heavy metals.In this paper, three heterocyclic organic ligands were selected to react with PTFE-AA to prepare novel chelating fibers. The synthesis route were speculated by characterization of structural changes in synthetic process. The adsorption and desorption behavior and regeneration ability of three kinds of fibers for five kinds of common heavy metal ions were studied, focusing on the properties of this fibers for Pb(Ⅱ). And, TGA was used as a evidence of adsorption of Pb(Ⅱ). The main content and the results are as follows:PTFE-AA recats with three nitrogen-containing elements of heterocyclic organic ligands, containing AP, AT and ABT, in order to synthesize three novel chelating fibers:APF, ATF and ABTF. The optimum synthesis conditions, functional group capacity and functional group conversion were determined by EA (elemental analysis), FT-IR (infrared spectroscopy) and TGA(thermo analyzer)and the fibers’ structure were characterized.EA (element analysis) results showed that, the scope of optimal synthetic conditions as follows, reaction molar ratio of APF, ATF, ABTF was4:1,5:1and4:1, respectively; reaction time of APF, ATF, ABTF was14h,14h and12h, respectively; reaction speed of APF, ATF, ABTF was250rpm,300rpm and300rpm, respectively; APF, ATF and ABTF function base conversion rate were46.3%,40.7%and42.1%, respectively.FT-IR(infrared spectroscopy) and TGA(thermo analyzer) results infered that the organic ligands had grafted to the matrixes successfully. Paths of synthesis confirmed to be condensation reaction which amino of ligands(AP, AT, ABT) reacted with carboxyl of PTFE-AA.Selective adsorption performance of five types common heavy metal ions Ni(Ⅱ), Cu(Ⅱ), Hg(Ⅱ), Zn(Ⅱ), Pb(Ⅱ) from aqueous solutions using batch and column adsorption methods has been investigated by using three kinds of novel chelating fibers, among which the focused-study was adsorption behavior and mechanism of Pb(Ⅱ). Batch studies proved that all the three kinds of fibers had high selection adsorption capabilities for Pb(II). Static test researches indicated three kinds chelating fibers had strongly selective adsorption for Pb(Ⅱ). The best adsorption pH of APF, ATF and ABTF were3.0,2.0and2.0respectively, while the saturated adsorption reached141.8,128.2and132.8mg/g respectively.Static desorption results also showed that3mol/L HC1,2mol/L HC1,3mol/L HC1solution provided effective desorption of Pb(Ⅱ) from APF, ATF and ABTF respectively.This three kinds of novel chelating fibers’ adsorption processes for Pb(Ⅱ) were compared with the secondary reaction kinetics model through discussing adsorption dynamics and apparent activation energy. It could be concluded that adsorption of Pb(Ⅱ) was mainly controlled by chemical adsorption. And the apparent activation energy of APF, ATF ABTF were29.3,36.4,21.7kJ/mol respectively.Isothermal adsorption curve researchs showed that the Pb(Ⅱ) adsorption processes of three novel chelating fibers could well accord with Langmuir isothermal adsorption model. Thermodynamic studies revealed that three novel chelating fibers on Pb(Ⅱ) adsorption processes were endothermic chemical reaction.APF, ATF and ABTF adsorption Pb(Ⅱ) are excellent regeneration and reuse performance after three times adsorption-desorption cycle.SEM, EDS, TGA studies proved that the three novel chelating fiber had good thermal stability during adsorption processes of Pb(Ⅱ), and the precipitation of Pb(Ⅱ) which loaded in chelating fibers ranged from200℃to500℃. |
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