Simple Preparation Of Polypyrrole-based Nanomaterials And Their Applications In Removal Of Organic Dyes

Compared with bulk-phase materials,the physical and chemical properties of the corresponding nanomaterials have been significantly changed.Nanoparticles usually displayed superior property in catalysis,and especially in reduction or degradation of organic dyes.Unfortunately,aggregation was one of the main drawback in their application.Anchoring them on a suitable support was verified to be an effective way to solve this problem.Polypyrrole?PPy?was an ideal support due to loose structure,light weight,large specific surface area,and positive charge on the main chain.Besides polypyrrole,graphene oxide was another suitable support for nanoparticles due to numerous functional groups on surface,high electron mobility and large specific surface area.Similar to a double-edged sword,the two-dimensional sheet-like graphene oxide was easy to stack,leading to a poor performance in application fields.By combining polypyrrole and graphene oxide,a three-dimensional interconnected porous structure was formed,leading to the maximum of their advantages.In addition,the nitrogen-containing carbon material not only had excellent adsorption property,but also played an important role in fixing and preventing the aggregation of nanoparticles.The refractory organic dyes could be completely degraded via a photo-Fenton method.Nanobead-based PPy hydrogel was prepared via a reactive-template method in one-step,where Fe₃O₄ NPs were selected as reactive-templates.Pyrrole monomer was polymerized to PPy in the presence of Fe³⁺cations,which was produced by etching Fe₃O₄ NPs with diluted HCl solution.During rhodamine?RhB?adsorption,PPy chains interacted with RhB molecules via hydrogen bond interaction and?-?interaction.The adsorption process was followed with pseudo-second-order kinetics and Langmuir model,indicating that physical adsorption and chemical adsorption co-existed.Besides served as good adsorbents,PPy hydrogel also could be used as an effective support for precious metal nanoparticles due to the hierarchical porous structure.In catalytic reduction of RhB,the catalysts displayed excellent activity and superior reusability.Pd-Fe₃O₄@PPy nanotubes with catalytic activity and superparamagnetic property were prepared by using MoO₃ nanorods as the starting-template in one-step.During the preparation procedure,removal of MoO₃ nanorods,preparation of Fe₃O₄ nanoparticles,synthesis of Pd nanoparticles and polymerization of pyrrole monomer were combined together.Reduction of 4-nitrophenol was selected as a model reaction to evaluate superior catalytic activity.The reaction rate constant and turnover frequency were as high as 0.318 and 368 min^-1,respectively.These two values were much higher than those reported in corresponding literatures,confirming the good catalytic ability of Pd-Fe₃O₄@PPy nanotubes.Reduced graphene oxide nanosheet?rGS?/Fe_x O_y/nitrogen-doped carbon layer?NCL?aerogel was prepared and showed superior photo-Fenton performance.Firstly,rGS/Prussion blue?PB?/PPy hydrogel was prepared as a precursor,and then it was calcinated under high-temperature in the presence of nitrogen atmosphere to form a three-dimensional hierarchical structure.During the photo-Fenton degradation of RhB,the effects of solution pH,Fe_x O_y loading,H₂O₂ and catalyst dosage,and RhB concentration were investigated.Radical trapping experiments revealed that^·OH radicals were the main active species;while e^-and h⁺also did their contributions on RhB removal.The degradation pathway of RhB were identified by mass spectrum.