Synthesis of polypyrrole nano-fibers with hierarchical structure and its adsorption property of Acid Red G from aqueous solution

• PPy hierarchical fibers (H-PPy) were synthesized in α-CD/I2 compound solution.
• Adsorption of Acid Red G onto H-PPy was high efficient and rapid.
• Adsorption capacity of H-PPy is about 2.3 times higher than that of conventional PPy.
• Adsorption behavior of H-PPy is well fitted to Langmuir isotherm.
• Thermodynamic parameters show the adsorption process is endothermic and spontaneous.

The polypyrrole nano-fibers with hierarchical structure were synthesized in α-CD/I2 inclusion compound solution via chemical oxidation by using FeCl3 as the oxidant. The formation of the hierarchical structured PPy was certified by Field Emission Scanning Electronic Microscope (SEM). Fourier transform infrared spectroscopy (FT-IR) results showed that the molecular structure of the prepared PPy backbone is same as the conventional PPy. From the results of X-ray fluorescence spectrometer (XRF) and X-ray diffraction (XRD) measurements, the α-CD/I2-Fe2+ is as the soft-template during the synthesis process of PPy with hierarchical structure. Some I− ions retained in the backbone of the prepared PPy were as the counter ion after rinse. PPy with hierarchical structure shows very good adsorption performance for the Acid Red G (azo dye). The adsorption equilibrium time was very short (within 30 min) and the maximum adsorption capacity (Qmax) was 121.95 mg/g, which is better than that of some other adsorbents reported in literatures. The hierarchical structured PPy that we prepared can be considered as a potential adsorbent for the removal of organic dyes from wastewater.