Synthesis and characterization of template-mediated mesoporous alumina nanostructures with efficient and fast adsorption of Congo red from aqueous solutions

Abstract

This article summaries an approach for the removal of organic dyes like Congo red using mesoporous alumina. Industrial effluents that contain dyes need to be treated before being discharged into surface water. The adsorption method has been established as a successful technique. Mesoporous alumina can be a suitable candidate for this adsorption purpose; so, it has been synthesized by the co-precipitation of aluminium sulphate as the aluminium source and a polysorbate type non-ionic surfactant (Tween-40) as the template. The composite was characterized by XRD, TEM, TG-DTA, etc. The calcined product at 600 °C was highly porous in nature having a BET surface area of 94 m² g⁻¹ as compared to other calcined products. The efficiency of the calcined product towards adsorption of the dye was investigated. This porous alumina out of Tween-40 exhibits excellent adsorption performance for Congo red and the decolourisation efficiency reached 99% in just 25 min. The adsorption parameters like agitation time, adsorbent dose and dye concentration were also varied. Moreover, the adsorption procedure was studied with various adsorption isotherms like Langmuir and Freundlich isotherms. Equilibrium adsorption data followed both Langmuir and Freundlich isotherms with a maximum multilayer adsorption capacity of 615 mg g⁻¹. Thus, the above porous alumina can act as a promising material for dye adsorption and can reduce pollution in waste water.