Spectroscopic signature of branched polyaniline nanotubules decorated with nanospheres as an adsorbent for chromium

Branched Polyaniline tubules decorated with nano polyaniline structures (PANI) were obtained by self-assembly during slow polymerization in strongly acidic conditions at 5 C. The surface area of PANI was found to be 37.6716 m(3)/g with a pore size of 149.6430 corresponding to a maximum pore volume of 0.08255 cm(3)/g. Thermogravimetric analysis indicated a three step weight loss attributed to loss of water, chloride and degradation of PANI. The potential of PANI in the acid doped form was investigated for Cr6+ ion removal. The effects of operating parameters including pH, contact time and Cr6+ concentration were examined by batch adsorption experiments. Optimum adsorption occurred at pH 5 with Langmuir monolayer adsorption capacity Q(max) of 182 mg/g. The adsorption process was diffusion controlled and was governed by pseudo second-order kinetics. The adsorption data were well fitted with Freundlich, Halsey and Elovich isotherm models indicating interactive and multilayer nature of the adsorption process. The applicability of PANI for removal of chromium from plating effluent was demonstrated.