Removal of 2-Aminophenol Using Novel Adsorbents

Removal of toxic substances from wastewaters using low-cost alternatives to activated carbon is an important area in environmental sciences. Efforts have been made to convert a fertilizer waste and a steel industry waste into low-cost potential adsorbents. The developed products have been used for the removal of 2-aminophenol from aqueous solutions and wastewaters. Studies were conducted to delineate the effects of temperature, initial absorbate concentration, particle size of the adsorbent, and solid-to-liquid ratio. Equilibrium isotherms were determined at selected pHʹs to assess the maximum adsorption capacity of the adsorbents. Both Freundlich and Langmuir models were used to interpret the adsorption data. The adsorption of 2-aminophenol is an endothermic process. Kinetic studies were performed, and various parameters such as mass transfer coefficient, effective diffusion coefficient, activation energy, and entropy of activation were evaluated to establish the mechanism of removal. Column studies were performed, and the breakthrough curves were used to optimize the contactors and identify a design correlation. Some feasibility experiments were also carried out with an aim to recover 2-aminophenol and demonstrate chemical regeneration of the spent columns. The column capacities of 312 and 30.00 mg/g were more than the batch capacities, which were 80.75 and 28.37 mg/g for activated carbon and activated slag, respectively. Overall, activated carbon developed from fertilizer waste exhibits better performance than activated slag developed from blast furnace slag.