Adsorptive removal of organic pollutants from water by carbon fiber aerogel derived from bacterial cellulose

This study concerns the adsorption of methylene blue (MB) and p-nitrophenol (PNP) as organic pollutants from aqueous solutions by carbon fiber aerogel (CFA) derived from bacterial cellulose. The adsorbent was fabricated by controlled pyrolysis of freeze-dried bacterial cellulose hydrogel and the structure was characterized by SEM, XRD, FTIR, and BJH techniques. In the adsorption process, effects of pollutant initial concentration, adsorbent dosage, and pH of the solution were evaluated in batch mode. Adsorption isotherms of MB and PNP followed the Langmuir and Freundlich models respectively, and the maximum adsorption capacities at room temperature and original pH were quantified to be about 106 and 60 mg g(-1) . Kinetics data of both pollutants perfectly followed the pseudo-second-order model. Thermodynamic studies revealed that MB adsorption was endothermic while PNP adsorption was exothermic and the changes in standard Gibbs free energy (Delta G degrees) and standard enthalpy (Delta H degrees) values suggested that both reactions were physisorption. The positive changes in standard entropy (Delta S degrees) represented increased solid-liquid interface irregularities and the negative values of Delta G degrees indicated that the reactions were spontaneous. Structural and dimensional properties of the adsorbent expedited its separation from the solution. [GRAPHICS] .