Synthesis of poly(3,4-propylenedioxythiophene)/MnO2 composites and their applications in the adsorptive removal of methylene blue

The poly(3,4-propylenedioxythiophene)/MnO2 composites (PProDOT/MnO2) were prepared successfully by soaking the PProDOT powders into potassium permanganate (KMnO4) solution, with the mass ratio of PProDOT and KMnO4 from 2:1 to 1:2. The structure and morphology of composites were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible absorption spectra (UV), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscope (FE-SEM). Furthermore, PProDOT/MnO2 composites were tested as the adsorbents for removal of methylene blue (MB) from aqueous solution. The results revealed that the composites were successfully synthesized, and the thiophene sulfur was oxidized into sulfoxide by KMnO4. The highest percentage removal of MB after 30 min was 91% for PProDOT/MnO2 (1:2) composite, and the percentage removal of MB was ~12 mg g−1 after 60 min at initial concentrations of MB dye of 5.6 mg L−1 in the case of PProDOT/MnO2 (1:2) composite. Besides, the adsorption process of PProDOT/MnO2 (1:2) composite was described by pseudo-second-order and Langmuir models.