Polyaniline and polypyrrole impregnated polyethersulfone based composite polymer beads for defluoridation application

Abstract

Various composite conductive polymeric beads were prepared by phase inversion method for defluoridation studies. Base polymer (polyether sulfone) was impregnated with doped and undoped polyaniline (dopant: para toluene sulfuric acid). However, highest fluoride uptake capacity of 40 mg/g was observed in case of polypyrrole (dopant: sodium lauryl sulphate) impregnated beads. Morphology of prepared beads revealed their porous characteristics. Apart from this, lauryl sulphate ions in doped polypyrrole chains played an important role in electrostatic adsorption of fluoride ions, as evident from spectral analysis. Optimum equilibrium conditions were obtained at an adsorbent dosage of 10 g/L. Uptake capacity of doped polypyrrole impregnated beads decreased with pH. Fluoride uptake by beads was endothermic and physical in nature. Adsorption kinetics followed pseudo-second order model. Negative effect was shown by carbonate and potassium ions while positive effect was shown by magnesium ions during uptake process. Regeneration was carried for six cycles and it showed a saturated uptake capacity for the last three cycles. Dynamic filtration studies were also carried out using these beads. It was observed that a microcolumn operated in gravity filtration mode can treat 0.05 and 0.03 times of its bed volume at maximum permissible levels of fluoride for distilled and tap water simulated feed solutions, respectively.