Residual diatomaceous earth as a potential and cost effective biosorbent of the azo textile dye Reactive Blue 160

Here we report the effective application of Residual Diatomaceous Earth (RDE) from brewery industry, in comparison to Residual Yeasts (RY) and Pure Diatomaceous Earth (PDE), for the removal of reactive blue 160 dye from aqueous solutions. RDE and the RY showed higher adsorption capacity at pH 2. Maximum dye removal capacity of PDE (1.51 mg g(-1)) was much lower than that observed for RDE and RY (7.96 mg g(-1) and 8.66 mg g(-1)), respectively, indicating that the presence of yeast in the biosorbent was fundamental for improving dye biosorption. The pseudo-second order kinetic model described well the adsorption processes for all the adsorbents. Equilibrium adsorption of the dye by RDE and PDE followed Langmuir isotherm, while RY best fitted with the Freundlich isotherm, indicating that the active sites of RY are more heterogeneous. FT-IR and Scanning Electron Microscopy analysis confirmed the presence of the dye on the surface of the adsorbents after the adsorption. Furthermore, the RDE presented several operational advantages when compared to the RY, indicating that it is a promising material to be used in wastewater treatment of textile industries.