Adsorption of Tannic Acid from Radioactive Waste Liquid by Graphene Aerogel
Three-dimensional graphene aerogels(3DrGO-Lcy)were prepared under atmospheric pressure in a water bath,and the adsorption of tannic acid from radioactive waste liquid was investigated.The structure and morphology of 3DrGO-Lcy were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD),Fourier transform infrared(FT-IR),and Raman spectra,and the effects of adsorption time,initial concentration,pH value,and adsorption temperature on the adsorption performance of tannic acid were studied.The adsorption mechanism of tannic acid by 3DrGO-Lcy was further investigated.The results showed that graphene oxide could be effectively crosslinked into three-dimensional porous aerogels with cysteine as crosslinking agent under normal pressure water bath condition.The adsorption equilibrium of tannic acid could be reached in 120 min.At an acidic pH of 4,the maximum equilibrium adsorption capacity of tannic acid reached 89 mg/g.Furthermore,the adsorption kinetics of tannic acid on 3DrGO-Lcy conformed to the pseudo-second-order kinetic model,while the isothermal adsorption process conformed to the Freundlich model,which indicated the adsorption of tannic acid on 3DrGO-Lcy occurred through a multimolecular layer chemisorption process involving π-π stacking and hydrogen bonding of functional groups.