Flower-like Mg/Fe-layered double oxide nanospheres with ultrahigh adsorption efficiency for anionic organic dyes

Flower-like Mg/Fe-layered double oxide (Mg/Fe-LDO) nanospheres were synthesized using a facile one-step hydrothermal method and applied to remove anionic organic dyes, namely, Congo red (CR) and methyl blue (MB) with excellent adsorption efficiency. The Mg/Fe-LDO nanospheres showed over 99% removal efficiency within 25 min and 5 min for CR and MB, respectively. The calculated maximum removal capacities for CR and MB were 1250 mg g−1 and 2000 mg g−1 at 298 K, respectively. The removal of such large quantities of organic dyes was attributed to the chemical adsorption between anionic CR and MB dye molecules and cationic Mg/Fe-LDO nanospheres through strong electrostatic interactions. Moreover, the reusability test results showed that Mg/Fe-LDO, as an efficient adsorbent, is stable for at least five cycles with over 99% dye removal efficiency. Therefore, it is believed that the excellent dye removal capacities, recycling ability, and facile synthesis of Mg/Fe-LDO nanospheres will facilitate their practical application in cost-effective wastewater purification.