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Sorptive removal of congored by polypyrrole alumina composite

M.Karthikeyan, K.Ramalakshmi, K.K.Satheesh Kumar, K.P.Elango

This study reveals the use of polypyrrole/Alumina (PPy/AlO) composite as an adsorbent for the removal of the dye, Congo red, from aqueous solution.Asmall amount (0.05 g/50 ml) of the adsorbent could decolorize as much as 18 mg/g of the dye from an aqueous solution (40 mg/L) at 30oC if agitated for an hour. The adsorption of the dye was appreciable in a wide range of pH. This showed that adsorption of the dye could be carried out using polypyrrole/ alumina composite without adjusting the pH of the medium. The experimental data yielded good fit with Langmuir when comphared to Freundlich isotherm equations. The values of the adsorption coefficients computed indicated the potential of the adsorbent for practical applications in colour removal process. The adsorption of Congo red onto polypyrrole/alumina was spontaneous at higher temperature and lower concentration. Change in enthalpy suggests the process is endothermic in nature. The enthalpy change for the adsorption process was observed to be 8-86 kJ mol-1, which indicated the absence of very strong chemical force between the adsorbed dye molecules and the polypyrrole/Alumina surface. Hence, physisorption seems to be the major mode of adsorption.