Polyaniline/silver (PANI/Ag) nanocomposite was prepared by chemical oxidative polymerization of aniline monomer in the presence of nitric acid. The formation of PANI/Ag nanocomposite was characterized by XRD, FTIR, TEM, UV-vis spectroscopy. The XRD patterns indicated that the crystalline phase of Ag is cubic with crystallite size of 93 nm. The TEM image shows that the Ag nanoparticles are well dispersed in the polyaniline matrix. Optical measurements show that the value of optical band gap of nanocomposite is lower than that of pure PANI. The DC-, AC-conductivities, dielectric permittivity (ε') and dielectric loss (ε'') of (PANI/Ag) nanocomposite and pure PANI have been measured in the temperature range from 303 to 723 K and frequency range from 10 to 10³ kHz. The electrical conductivity of the (PANI/Ag) nanocomposite is higher than pure PANI. Temperature variation of frequency exponents in this blend suggests that AC-conductivity is attributed to correlated barrier hopping mechanism. At all frequencies, the ε' value for (PANI/Ag) nanocomposite is higher than that for pure one. The higher dielectric constant of the PANI/Ag nanocomposite indicates their better ability to store electric potential energy under the influence of alternative electric field

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Silica and montmorillonite-supported silica nanoparticles were prepared via an acid one step sol-gel process. The synthesized solids were characterized using XRD, FTIR, TEM and N 2 adsorption. The effect of preparing temperatures on the structure and properties of the silica nanoparticles were studied. The results show that the increase of annealing temperature from 25˚C to 200˚C, don't change amorphous state of silica. While for montmorillonite-supported silica the clay platelets are delaminated during the sol-gel process. TEM results showed that the average particle size of silica is increased by increasing temperature due to the particle sintering and the clay-silica nanoparticles possessed core-shell morphology with diameter of 29 nm. The surface area measurements showed that by increasing annealing temperature the surface area was decreased due to aggregation of particle. The clay-silica sample showed lower average pore width than that of the silica prepared at 200˚C indicating that it has a macropores structure. The adsorption efficiency of the prepared samples was tested by adsorption of protoporphyrin IX. The highest adsorption efficiency was found for SiO 2 prepared at 200˚C. Temkin model describe the equilibrium of adsorption of protoporphyrin IX on caly-silica nanoparticles under different conditions.

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