A Spherical Zwitterionic Cellulose Acetate/ Graphene Oxide Composite Adsorbent for Efficient Removal of Cu2+ and Cd2+ from Aqueous Solution

A novel composite adsorbent was prepared by using cellulose acetate modified with zwitterion, for zwitterionic cellulose acetate (ZCA), then blended with graphene oxide (GO). The adsorbent was prepared by sol-gel method and used to remove Cu2+ and Cd2+ from aqueous solution. The morphologies, surface chemical structures, and crystallinity of the obtained adsorbents were characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffractometer (XRD), respectively. N-2 adsorption-desorption measurements revealed that the surface area and pore volume were 45.3 m(2)g(-1) and 0.249 cm(3)g(-1). For adsorption, effect of time, and pH, adsorbate concentration was investigated; different adsorption models were also evaluated. The results showed that the maximum adsorption capacity was 32.0 mg/g for Cu2+ and 27.6 mg/g for Cd2+, observed at pH 5.5 and 298 K. Simultaneously, the adsorption isotherms were well-fitted to the Langmuir model, and kinetics study showed that the adsorption process was fitted well by the pseudo-second-order model. Further regeneration experiments revealed that the adsorption of ZCA/GO was about 90% of the initial saturation adsorption capacity after repeated use 5 times, indicating that they are promising absorbents for practical application in industry.