Synthesis and properties of the compositе polyanylin–ferrocianide

Abstract

Samples of polyaniline and polyaniline-ferricyanide composites were synthesized by the reaction of oxidation polycondensation of aniline. Ammonium peroxide disulfate (NH 4 ) 2 S 2 O 8 was used as an oxidizing agent in this reaction, which was performed in an acid medium (aniline + HCl) or (aniline + H 3 [Fe (CN) 6 ]). Structures of synthesized chemical compounds were studied by IR spectroscopy. Spectral analysis shows the presence of light absorption bands at 1 140 cm-1, which are due to oscillations of the group of atoms –N=Q–N + –B–, which is characteristic of the polaron state of the links of the polyaniline chain. The peak at 1450 cm -1 corresponds to deformation oscillations –N = Q = N groups of polyaniline, and the absorption band with a peak at 1600 cm -1 refers to the deformation oscillations of the N–H groups. An analysis of the results of an IR spectroscopic study suggests that the structure of the composite corresponds to the structure of the emeraldalin salt of polyaniline. The coloring of aqueous solutions of salts containing Cu 2+ ions indicates that they absorb light in the visible range of the spectrum. To determine the wavelength at which the maximum absorption of light is achieved by solution of CuSO 4 , the UV spectrophotometer of theCuSO 4 solutions in the visible region (500–900 nm) was measured with the concentration range 0.00625–0.2 M, from which the maximum was determined. The absorption of light by hydrated Cu 2+ ion accounts for a wavelength of 810 nm. All subsequent measurements of the optical density of the investigated solutions were performed at wavelengths 810 nm. A study was performed on adsorption of CuSO 4 from aqueous solutions on the surface of the polyaniline-ferrocyanide composite at 20 C. To measure adsorption, a method was used to determine the optical density of the solution above the adsorbent. An analysis of experimental data suggests that the polyaniline composite {PAn + H 3 [Fe (CN) 6 ]} is the best adsorbent for heavy metal ion Cu 2+ than the polyaniline itself, the amount of CuSO 4 adsorption on the polyaniline-ferocyanide composite is 0.007 mole/g adsorbent. The presence of a conjugated system in the structure of the polyaniline chain, the component of which are nitrogen atoms with 2 s electron vapor, makes it possible to form complexes of polyyaniline with metal ions, which have vacant electrons for the 3 d energy level. The ferrocyanide ion increases the charge density on polyaniline chains, thereby improving the ability of the composite to adsorb Cu(II) from the aqueous solution. The cyanide complex of the composite can take ions of metals from solutions through the coordination mechanism of the inner sphere, which determines the synergistic effect of the composite components (polyaniline chains and ferrocyanate adsorption centers). Keywords : polyaniline, polyaniline-ferricyanide composites, adsorption Cu 2+ .