The use of red mud nano-particles for the removal of methylene blue and Eriochrome Black T from polluted waters

Organic compounds especially dye materials are considered as an emerging environmental problem due to their continuous input and persistence into the aquatic ecosystem even at low concentrations [1]. Using red mud as unconventional adsorbents for water and wastewater treatment purposes are motivated by the fact that red mud is a fine-grained mixture of oxides and hydroxides, capable of removing several contaminants, as well as being widely available [2]. In the present study, the adsorption of organic dyes, Methylene Blue (MB) and Eriochrome Black T (EBT), from aqueous solutions was investigated using low-cost, natural, and reused adsorbent, Red Mud, as an ideal alternative to the current expensive methods of removing organic pollutant compounds from wastewater. The adsorption studies were carried out under various parameters, such as pH, sorbent dosage, contact time, and initial dye concentration in batch experiments and one at a time procedure. The experimental results show that the percentage of adsorption increases with an increase in the adsorbent dosage, contact time, and initial dye at beginning the process. The maximum adsorption occurred at the pH value of 7 for Methylene Blue and Eriochrome Black T. Adsorption kinetic data were properly fitted with the pseudo-second-order kinetic model. The experimental isotherms data were analyzed using Langmuir, Freundlich and Tempkin isotherm equations. The Tempkin and Freundlich model obtained the best fit for EBT and MB, respectively. Maximum sorption capacity was 2.41 mg/g for Methylene Blue and 0.91 mg/g for Eriochrome Black T.