Fabrication Of Magnetic Polypyrrole Based Composites For The Adsorption Of Cr(?)and Ag(?)

In recent years,a large number of wastewater containing heavy metal ions was discharged into the environment due to the rapid development of industrialization,which will not only pollute the environment seriously,but also harm human health.Therefore,it was urgent to treat wastewater containing heavy metal ions.Adsorption was considered to be the most simple and effective treatment method.How to design and synthesize of adsorbents with excellent adsorption capacity and recyclable regeneration is great significance for the removal of heavy metal ions from wastewater.In this thesis,magnetic polypyrrole based nanocomposites loaded with different magnetic nanoparticles Fe₃O₄ and Fe were designed and synthesized,and the magnetic polypyrrole based nanocomposites were used as adsorbents to study the adsorption of heavy metal ions and regeneration.The specific research contents are as follows:(1)A simple and efficient route was proposed to fabricate magnetic polypyrrole(Fe₃O₄/PPy)nanotubes via one-pot process.The effect of Fe³⁺content on the morphologies,structures and properties of the Fe₃O₄/PPy nanotubes were investigated.The results show that Fe₃O₄/PPy exhibits a tubular structure,and the Fe₃O₄ magnetic nanoparticles were uniformly dispersed on the PPy nanotubes.With the increase of Fe³⁺content,the diameter of PPy nanotubes in Fe₃O₄/PPy nanotubes decreased slightly,and the content of Fe₃O₄ increased.The saturation magnetization of Fe₃O₄/PPy nanotubes increases from 7.41 emu/g to 40.45 emu/g.Except for S1,Fe₃O₄/PPy nanotubes exhibit excellent magnetic properties.(2)The adsorption capacity of Fe₃O₄/PPy nanotubes for Cr(?)was investigated.The effects of initial concentration of Cr(?),p H value and other factors on the adsorption performance were investigated.The adsorption process of Cr(?)was studied by kinetic and isothermal adsorption model s,the adsorption mechanism and recycling performance were studied.The results show that the adsorption capacity of Fe₃O₄/PPy nanotubes for Cr(?)increased with the decrease of Fe³⁺content.When n(Py:Fe³⁺)was 0.6,adsorption capacity was 451.47 mg/g.The adsorption process of Cr(?)on Fe₃O₄/PPy nanotubes were in accordance with Langmuir isothermal model and pseudo-second-order kinetic model,which showed that the adsorption process was mainly single layer adsorption.XPS analysis showed that the adsorption mechanism was ion exchange and chelation,and part of Cr(?)was reduced to Cr(?)due to the existence of-NH⁺.Furthermore,Fe₃O₄/PPy nanotubes adsorb Cr(?),after five adsorption/desorption cycles,the removal rate of Cr(?)was 90%,which indicates that Fe₃O₄/PPy nanotubes have good regeneration performance.(3)Fe doped polypyrrole matrix carbon nanotube composites(Fe/CNTs)were synthesized by one-pot in-situ carbothermic reduction method.The morphologies and properties of Fe/CNTs composites were characterized and analyzed.The adsorption properties of Fe/CNTs composites for Ag(I)were studied,and the kinetic and isothermal adsorption processes of Ag(I)were discussed.The results show that the Fe/CNTs composites form a uniform tubular structure when n(Py:Fe³⁺)is 0.4,and the Fe nanoparticles formed by in-situ carbothermal reduction are dispersed in the CNTs.The saturation magnetization of the composites is 64.85 emu/g,showing excellent magnetic properties.In addition,adsorption capacity of Fe/CNTs composites for Ag(I)is much higher than that of Fe and CNTs,the maximum adsorption capacity was522.41 mg/g.The adsorption process of Ag(I)on Fe/CNTs composite s conforms to the pseudo-second-order and Langmuir isotherm adsorption model,indicating that the adsorption process is dominated by monolayer adsorption.