Dye removal by incineration residues of pharmaceutical wastes in aqueous solution

The batch removal of Basic Red 46 (BR 46) from aqueous solution using low-cost adsorbents, such as incineration residues (IR) of pharmaceutical wastes, under different experimental conditions was investigated in this study. The effects of initial BR 46 concentration (10, 25, 50, 75, and 100 mg L−1), amount of residues CS (10, 15, 20, 30, and 40 g L−1), pH (3, 5, 7, 9, and 11), and temperatures T (284, 293, 306, 316, and 346 K) have been reported. Adsorption of BR 46 is highly dependent on the initial pH, the amount of adsorbent, and temperature. Results showed that BR 46 removal increased up to 94%. The adsorption phenomenon governing this process was best described by the Langmuir. Equilibrium data fitted well with the Langmuir isotherm model. The monolayer sorption capacity was found as 12.04 mg g−1. A comparison of kinetic models applied to the adsorption of BR 46 on the adsorbent was evaluated for the pseudo-first-order and the pseudo-second-order. Results show that the pseudo-second-order kinetic model was found to correlate perfectly with the experimental data. The activation energy for BR 46 sorption onto the IR was found to be 30.53 kJ mol−1, indicating a physical process. The adsorption of BR 46 was endothermic and spontaneous. From the experimental results, it may be concluded that IRPW seems to be an efficient and economical adsorbent for BR 46 removal.