Facile fabrication of porous NiCo₂O₄ nanosheets with high adsorption performance toward Congo red

In this work, porous NiCo₂O₄ nanosheets have been fabricated by a facile hydrothermal method. The morphology as well as crystalline structure of products was tested by XRD, FTIR, N₂ adsorption-desorption isotherms and TEM. The composite exhibited excellent adsorptive removal capacity toward Congo red (CR), and the maximum adsorption capacity was up to 961.5 mg/g. The best adsorption performance was achieved in the CR solution without adjusting of pH. Adsorption accords with Langmuir isothermal adsorption model and the adsorption kinetic model is more in line with the pseudo-second order model. According to the adsorption mechanism investigation, adsorption was not caused by the electrostatic attractions but may be the formation of ionic bonding between metal ion in composite and -SO₃ ^- in CR. The NiCo₂O₄ nanosheets can be a good alternative for the high-performance Congo red adsorbent.