Synthesis and characterization of polypyrrole, polyaniline nanoparticles and their nanocomposite for removal of azo dyes; sunset yellow and Congo red

Polypyrrole, polyaniline nanoparticles and their nanocomposites were prepared using microemulsion polymerization method. For the synthesis of polypyrrole and polyaniline nanoparticles sodium dodecyl sulfate as a surfactant for two reasons was used; to the creation of a micro reactor vessel and to improve the physical properties of polymers such as stability, solubility in organic solvents, conductivity, and processability. These nanoparticles were dedoped through 20% NaOH solution. The removal of sunset yellow and congo red dyes was carried out using both doped and dedoped species and nanocomposites at room temperature and under ultrasound irradiation. Also, the effect of adsorbent dosage, initial pH, effects of contact time on adsorption and ultrasonic power as experimental parameters on the removal of the sunset yellow and congo red dyes was investigated. It was found that all of the premade species including multiwall carbon nanotubes, carboxylate-multiwall carbon nanotubes, polypyrrole, polyaniline, polypyrrole/multiwall carbon nanotubes and polyaniline/multiwall carbon nanotubes can be used for removal of anionic dyes such as sunset yellow and congo red from water solutions. The highest removal efficiency for sunset yellow dye (∼99%) was achieved at 0.007 g of polypyrrole/multiwall carbon nanotubes nanocomposite, at pH = 2, at ambient temperature and at ultrasonic irradiation power 500 W and for congo red dye the highest removal efficiency (∼98%) was achieved at 0.01 g of polypyrrole/multiwall carbon nanotubes nanocomposite, at pH = 2, at ambient temperature and at ultrasonic irradiation power 500 W. The polypyrrole/multiwall carbon nanotubes and the polyaniline/multiwall carbon nanotubes adsorbents, the recovery achieved more than 80% with the proportion of 55:45 from acetone: H2O. The strong adsorption capacity of polypyrrole/multi-walled carbon nanotubes and the polyaniline/multiwall carbon nanotubes nanocomposites prepared with ammonium per sulfate as initiator can be attributed to the π-π electron donor-acceptor interaction and electrostatic attraction. The nanoadsorbents multiwall carbon nanotubes, carboxylate-multi-walled carbon, polypyrrole/multiwall carbon nanotubes and the polyaniline/multiwall carbon nanotubes produced with ammonium per sulfate as initiator was used to removing azo dyes from H2O through efficient microscale filtration and can be scaled up for commercial and industrial applications.