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

摘要

Polypyrrole (PPy) and polyaniline (PAni) conducting polymers were synthesized chemically on the surface of wood sawdust (SD) to remove Eosin Y (EY), an anionic dye, from aqueous solution. The important parameters such as pH, initial concentration, sorbent dosage and contact time on uptake of EY solution were also investigated. The experiments were carried out using both batch and column systems at room temperature. It was found that both polymers can be used to remove anionic dyes such as EY from aqueous solutions very efficiently. The sorption process of EY dye using both polypyrrole and polyaniline coated onto sawdust (respectively termed as PPy/SD and PAni/SD) was less dependent on the pH of the solutions at least at pH values from 2-10. Considerable decrease in sorption performance occurred only at high pH values (pH ≥ 12). According to our "breakthrough analysis", it was found that PAni/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 examined by pseudo-first-order and pseudo-second-order models, and their respective rate constants of first-order adsorption (k_1) and second-order adsorption (k_2) were estimated. The experimental data fitted very well into pseudo-second-order kinetic model. The experimental data were also analyzed by the Langmuir and Freundlich models of adsorption. Based on the correlation coefficient values obtained (R~2), it was found that equilibrium data fitted well with both models. In order to find out the possibility of desorption for frequent use, the chemical regeneration of the employed adsorbents was also investigated. It was found that more than 96% of the EY dye can be recovered from PPy/SD column using a dilute NaOH solution (0.05 M).