Removal of Eosin Y, an Anionic Dye, from Aqueous Solutions Using Conducting Electroactive Polymers

Polypyrrole (PPy) and polyaniline (PAni) conducting polymers were synthesizedchemically on the surface of wood sawdust (SD) to remove Eosin Y (EY), ananionic dye, from aqueous solution. The important parameters such as pH,initial concentration, sorbent dosage and contact time on uptake of EY solution werealso investigated. The experiments were carried out using both batch and columnsystems at room temperature. It was found that both polymers can be used to removeanionic dyes such as EY from aqueous solutions very efficiently. The sorption processof EY dye using both polypyrrole and polyaniline coated onto sawdust (respectivelytermed as PPy/SD and PAni/SD) was less dependent on the pH of the solutions at leastat pH values from 2-10. Considerable decrease in sorption performance occurred onlyat high pH values (pH ≥ 12). According to our "breakthrough analysis", it was found thatPAni/SD adsorbent is more efficient for EY removal in flow or column system.Adsorption of EY on the PPy/SD and PAni/SD under different conditions was examinedby pseudo-first-order and pseudo-second-order models, and their respective rateconstants of first-order adsorption (k1) and second-order adsorption (k2) wereestimated. The experimental data fitted very well into pseudo-second-order kineticmodel. The experimental data were also analyzed by the Langmuir and Freundlichmodels of adsorption. Based on the correlation coefficient values obtained (R2), it wasfound that equilibrium data fitted well with both models. In order to find out thepossibility of desorption for frequent use, the chemical regeneration of the employedadsorbents was also investigated. It was found that more than 96% of the EY dye canbe recovered from PPy/SD column using a dilute NaOH solution (0.05 M).