Activated carbons from flamboyant pods: New types of adsorbents and application to laundry effluents

Abstract In recent years, the perception that conventional treatment of waters and effluents produce secondary effluents containing various substances still considered toxic has increased the investigation for more efficient treatment methods. The adsorption process on activated carbons (ACs) is an acknowledged tertiary method or of post-treatment of effluents. In this work, several ACs obtained from the flamboyant pods were used for the first time for the treatment of effluents generated in an industrial laundry. The adsorbents produced by chemical activation and physical activation presented high surface areas (from 265.5 to 561.1 m2 g−1), microporous and mesoporous physical characteristic and various acidic and basic functional groups. Two types of effluents (one raw and another previously treated through activated sludge) were submitted to adsorption processes and a decrease of the initial values of apparent color, turbidity and COD was observed. On the other hand, the results indicated that the contribution of the porous membranes (used in the filtration step) for the adsorption process must be considered in order to assess the real adsorption capacity. Furthermore, the UV–vis spectra of the effluents indicated the ACs have a high capacity of adsorption of compounds which absorb in the visible and ultraviolet regions. The adsorption of several components present in the effluents suggests that the flamboyant pods can be explored to produce several ACs with potential to be applied together (as auxiliary agents) with conventional treatments and to improve the reuse of secondary effluents produced after biological treatment.