Bioadsorption of Basic Blue Dye from Aqueous Solution onto Raw and Modified Waste Ash as Economical Alternative Bioadsorbent

Background. Dyes are one of the most hazardous materials in industrial effluents which can cause several health problems in living organisms. The removal of dye from colored effluents has attracted increasing attention in the last decade. In this study, raw, beneficiated, and activated waste ash were evaluated as adsorbents for removal of methylene blue (MB) from aqueous solution by the batch adsorption method. Comprehensive characterization studies were carried out on each bioadsorbent, such as proximate analyses, bulk density, specific surface area, point of zero charge, pH, and Fourier transform infrared (FTIR) spectroscopy (which shows functional groups on adsorbents surface). The effects of pH, adsorbent dosage, initial dye concentration, and contact time were determined in order to know the optimum condition and adsorption potential of the adsorbents. The methylene blue (MB) removal efficiency of raw, beneficiated, and activated bioadsorbents from aqueous solutions was found to be 95.212%, 89.172%, and 84.504%, respectively. It is reported that adsorption efficiency of MB on each adsorbent was quite different due to electrostatic and dispersion interaction between the dye molecules and the surface property of the adsorbents. The obtained results were well fitted with the Freundlich isotherm model, and the adsorption process follows the pseudo-second-order kinetics model for all adsorbents. In fact, the results showed that raw, beneficiated, and activated waste ash bioadsorbents could be employed as effective and economical alternative material in the near future.