Removal of Cr(VI) by ammonia-modified biomass adsorbent

The non-biodegradability and microtoxicity of harmful anions in water, especially hexavalent chromium, have caused serious damage to the environment and human health. Therefore, research on efficient and environmentally friendly adsorbents for the removal of Cr(VI) becomes essential. In this paper, we propose for the first time to effectively remove Cr(VI) anion by aminated graphene oxide/cellulose oxide nanocellulose/sodium alginate porous materials (NH2-GO/NOC/SA) prepared by cross-linking aminated graphene oxide with biomass materials (oxidized nanocellulose and sodium alginate) via epichlorohydrin. The porous materials were characterized using tools such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), electroluminescence (EDS), Brunauer Emmett Teller (BET), and X-ray photoelectron spectroscopy (XPS) analysis. The optimum adsorption performance of the porous material was obtained by varying the initial concentration (from 100 to 500 mg/L), pH (from 1 to 8), and adsorption time (from 15 min to 72 h) of the Cr(VI) solution. The analysis of the adsorption data showed that the adsorption process was more in line with the pseudo-second-order kinetic equation and Langmuir isotherm model, and the equilibrium adsorption amount reached 394.1 mg/g. The adsorption of Cr(VI) on the NH2-GO/NOC/SA porous material was achieved by electrostatic interactions, Schiff base chemical bonding energy, ion exchange, protonation, precipitation, and hydrogen bonding. In conclusion, the experimental results show that the biomass adsorbent NH2-GO/NOC/SA can be consistently applied to remove Cr(VI) from wastewater.