Layered double hydroxides with tuned nanoscale morphology as active adsorbents of two industrial dyes from water

Abstract

Materials with a regulated nanoscale morphology can remove dangerous pollutants from wastewater by adsorption. Layered double hydroxides (LDHs), with the advantage of their high surface area and combined micro-nanomorphology features, have emerged as promising candidates for obtaining versatile and robust adsorbents. This work presents how the tuned synthesis of MgAlLDH (e.g. temperature) tailored their nanoarchitecture, giving rise to adsorption capacities toward cleaning aqueous samples polluted with the industrial dyes Drymaren Navy (DN) and Drymaren Red (DR). MgAl-LDH was prepared by the co-precipitation method, with aging temperatures of 25, 45, 65 and 85 °C, to study the effect of the synthesis conditions on the adsorption properties of the DN and DR dyes. The results show that the crystallinity, particle size and surface area were improved by increasing the synthesis temperature of the LDH, and therefore the adsorption rates and capacity were improved. Isotherm studies show that the Langmuir isotherm model was appropriate for describing DN and DR’s adsorption onto the LDHs. Thermodynamic parameters show that the adsorption processes of both dyes were endothermic, spontaneous and physical in nature. The memory effect could regenerate LDH due to the reconstruction of the material after calcination and rehydration with dye solutions. Therefore, we explored the tuned nanoscale morphology of MgAlLDH for obtaining performance adsorbents to eliminate refractory pollutants in wastewater.