Carboxymethyl Cellulose-Grafted Graphene Oxide/Polyethylene Glycol for Efficient Ni(II) Adsorption

Abstract

Carboxymethyl cellulose-grafted graphene oxide blended with polyethylene glycol composite hydrogel as a new adsorbent was prepared. Firstly, graphene oxide was synthesized from sugarcane bagasse as a plentiful waste via a single-step oxidation under muffled atmospheric conditions. Furthermore, carboxymethyl cellulose was prepared from extracted cellulose and grafted onto graphene oxide by different ratios. The grafted graphene oxide was blended with polyethylene glycol in presence of glutaraldehyde as a cross linker to form a triple network hydrogel. The structures and morphologies of the prepared composite were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and TGA/DTA analysis. The prepared composites were used as adsorbents for the removal of Ni ions from aqueous solution. Different adsorption conditions were investigated such as; time intervals (15–90 min), Ni2+ concentrations (15–30 ppm), and temperature (298–328 K). The kinetics and isotherms were studied to highlight the adsorption rate and mechanism of the adsorption process. The results showed that the hydrogels fitted with the Langmuir isotherm model and the pseudo-second order with the best fit of R2. On the other hand the positive values of ∆H, the negative values of ΔG, and the positive values of ∆S indicated that the Ni2+ adsorption is an endothermic process. The prepared hydrogels showed promising properties as the adsorption materials.