Polyaniline/Polypyrrole Electrochemical Synthesis And Their Performance Research

The Polyaniline?PANI?has been much researched on photoelectric materials,corrosion resistant,catalysis and sensor because of its easy preparation,simple to synthesis,cheap raw material,stability,excellent physical and chemical properties,though less on adsorption.Moreover,PANI contains lots of imine and amine groups,which has good removal of heavy metals and dyes from effluents.In this paper,PANI were prepared by electrochemical cyclic voltammetry from aniline wastewater under different pH.The influences of pH,potential and doped pyrrole on the synthesis of PANI were studied,as well as they were used as adsorbent on the treatment of wastewate.Polyaniline were prepared by electrochemical cyclic voltammetry conducted in solutions of aniline of different pH.The synthetic products were characterized by FITR,SEM and UV-Vis.PANI was easier to be synthesized under acidic condition and its rate of synthesis of PANI was significantly faster than that of the neutral and alkaline conditions.Moreover the former surface was smooth and mostly in a complete plane mixed with flakes,while the latter were disordered granular products.Then PANI synthesized under acid solution?pH=1.00?was used as adsorbent and its adsorption for Congo red was systematically examined through batch experiments.The experimental results showed that the optimal conditions were obtained after 4h of adsorbate/adsorbent contact with initial of Congo red was 100mg/L.The UV-Vis characterization indicated that Congo red molecules absorbed on PANI by electrostatic attraction due to the fact that amino groups of PANI were protonated at low pH.The adsorption kinetic data followed the pseudo-second-order equation and the equilibrium data fitted well to Langmuir model,which showed that the adsorption process was a chemical adsorption process and PANI had a good adsorption for Congo red with maximum adsorption capacity of 58.07 mg/g?Langmuir fit?.The formation rate and surface morphology of PANI could be controlled by changing the polymerization potential.The lower limit potential had little effect on the PANI in the range of-0.5V-0V,while the effect of upper limit potential was crucial.The appropriate of upper limit of the potential was controlled in the vicinity of 1.5V,then could get long sheet of polyaniline and avoid the high potential side effects caused by too high potential.Then PANI synthesized under the potential-0.5V-1.5V was used as adsorbent and its adsorption for Cr⁶⁺was systematically examined through batch experiments.Adsorption results demonstrated that concentration,pH,anion salt,temperature and time all had an effect on the adsorption of Cr⁶⁺on polyaniline,especially pH.The amount of Cr⁶⁺by PANI could reach120mg/g under the acidic condition.The adsorption kinetics showed that the adsorption process was in accordance with the pseudo-second-order kinetic model,indicating that the adsorption mechanism were mixed with the diffusion process,the surface adsorption process and the process of diffusion of ions.Thermodynamic parameters proved that the adsorption of Cr⁶⁺on PANI was endothermic and increased the degree of disorder,and higher temperature could increased the possibility of adsorption.On the basis of fixed pH and potential,PANI-PPy copolymers were prepared by addition of pyrrole,then characterized by IR and Raman spectrums.The SEM micrographs indicated that:lose and thick structure of PANI became compact structure of PANI-PPy and the degree of aggregation of PANI-PPy significantly decreased,which ascribed to added pyrrole.Then PANI-PPy?ratio of monomer,aniline/pyrrole=6/4?was used as adsorbent and its adsorption for phosphate was systematically examined through batch experiments.The results indicated that concentration and pH had greater effect on the adsorption of phosphate than anionic salt and temperature.