Tetraethylenepentamine modified magnetic cellulose nanocrystal composites for removal of Congo red with high adsorption capacity

Abstract

A tetraethylenepentamine modified magnetic cellulose nanocrystal composites (Fe3O4@CNC-TEPA) was prepared by the coprecipitation method and Schiff base reaction, which could adsorb Congo red (CR) efficiently. The morphology and structure of the nanoparticles were characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), zeta potential (ZETA), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). Subsequently, the Fe3O4@CNC-TEPA adsorbed CR was investigated by comparative experiments, selective adsorption experiments, effect of pH, effect of adsorbent dosage, adsorption isotherms, thermodynamics parameters, adsorption kinetics, leaching experiments, desorption and reusability experiments. Results revealed the fact that the nanoparticles showed excellent adsorption capacity of CR (1049 mg g−1) due to the abundant hydroxyl and amino groups on the surface of the Fe3O4@CNC-TEPA. The adsorption process was best described by the the Langmuir equation and pseudo-second-order kinetic model. Moreover, the Fe3O4@CNC-TEPA loaded with CR can be recycled with NaOH solution easily, which can be used repeatedly for CR adsorption. After six cycles, the adsorption capacity was still about 81.5% of the original particles’. The environmentally friendly nanoparticles have great application prospects as adsorbents for removing CR.