This research endeavored to develop a new application of polypyrrole (PPy) and polyaniline (PAn) synthesized in the presence of ferric chloride and potassium iodate as oxidants and coated on carbon nanotubes (CNT). The removal of heavy metals, anions, and chemical oxygen demand from paper mill wastewater was compared when polyaniline, polypyrrole, and their nanocomposites with carbon nanotubes were used for this purpose. It was found that PPy/CNT and PAn/CNT could be used as effective adsorbents in the wastewater treatment. Also, the synthesized products were investigated in terms of morphology, molecular structure, and thermal stability by using scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermal gravimetric analysis. J. VINYL ADDIT. TECHNOL., 19:213-218, 2013. © 2013 Society of Plastics Engineers