Rapid mixing polymerization: A simple method for preparation of free standing polypyrrole film and powder for the removal of anionic pollutants

Abstract

Polypyrrole has been synthesized by rapid mixing of the monomer and ferric chloride (FeCl3) solutions. By this method, free standing polypyrrole films at the air/water interface along with bulk polypyrrole powder (R-PPy) are formed as a result of a single step reaction. We have reported the characterization of R-PPy and its application for removal of anionic pollutants such as Eosin yellow, Eosin blue, Orange (II), Reactive orange, Orange G and Cr(VI) from aqueous medium. The materials synthesized were characterized by Scanning electron microscopy (SEM), Zeta potential measurement, Powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) spectroscopy and Thermal gravimetric analysis (TGA). R-PPy shows an enhanced adsorption capacity compared to the polypyrrole (PPy) samples synthesized by conventional chemical polymerization method. The percentage removal of EY increases from 58.8 % for PPy to 95.3 % in R-PPy and for Cr (VI) removal, it is 40.2 % for PPy which increases up to 69.5 % on using R-PPy for a definite initial concentration of the pollutants. The reduced agglomeration due to the synthetic procedure and a more positive surface charge density on the R-PPy particles are the reason for improved adsorption capacity of R-PPy than that of conventionally synthesized PPy. We have studied the effect of initial concentration, adsorbent dose, solution pH and temperature on the adsorption capacity. The adsorption was found to follow pseudo second order kinetic model. The Langmuir adsorption capacity of R-PPy was found to be 273.2 and 103.6 mg/g for EY and Cr (VI), respectively at 303 K. The thermodynamic parameters revealed that the adsorption is endothermic and spontaneous.