ABSTRACT
A chemical exfoliation and freeze-drying technique was used to create graphene oxide/graphene oxide nanoribbons/chitosan aerogels (GO/GONRs/CS). Aerogels were utilized to study uranium adsorption through batch experiments. Environmental influences on U(VI) adsorption were studied, including the starting concentration of U(VI), contact time, pH, and temperature. In order to characterize the composite, FTIR, SEM, XRD, and TEM analyses were used. A pseudo-second-order kinetic model may adequately represent the kinetics of U(VI) adsorption onto the surface of aerogels. The Freundlich model can explain the adsorption isotherm; the maximal adsorption capacity for U(VI) was determined to be 1208.85 mg/g; the adsorption process for U(VI) was endothermic, spontaneous, and pH-dependent; and the mechanism of adsorption is the chemisorption process. Chemisorption typically involves strong chemical interactions between the adsorbate (uranium ions) and the functional groups present on the surface of the adsorbent (the aerogel). Graphene oxide and graphene oxide nanoribbons contain oxygen-containing functional groups such as carboxyl (-COOH), hydroxyl (-OH), and epoxy (-O-) groups, which can act as active sites for chemical bonding. Chitosan, a polysaccharide derived from chitin, also possesses functional groups like amino (-NH2) and hydroxyl groups. Uranium ions, in their U(VI) form, can form chemical bonds with these functional groups through various mechanisms such as electrostatic interactions, complexation, and coordination bonds. The combination of graphene oxide-based materials and chitosan in the nanocomposite aerogel offers several advantages, including a large specific surface area, chemical stability, and the presence of functional groups for effective uranium adsorption.
ABSTRACT
Waste-water pollution by radioactive elements such as uranium has emerged as a major issue that might seriously harm human health. Graphene oxide, graphene oxide nanoribbons, and sodium alginate nanocomposite aerogels (GO/GONRs/SA) were combined to create a novel nanocomposite using a modified Hummer's process and freeze-drying as an efficient adsorbent. Batch studies were conducted to determine the adsorption of uranium (VI) by aerogel. Aerogels composed of (GO/GONRs/SA) were used as an effective adsorbent for the removal of U (VI) from aqueous solution. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to describe the structure, morphologies, and characteristics of (GO/GONRs/SA) aerogels. The initial concentration of uranium (VI) and other environmental factors on U (VI) adsorption were investigated, period of contact, pH, and temperature. A pseudo-second-order kinetic model can be employed to characterize the kinetics of U (VI) adsorption onto aerogels. The Langmuir model could be applied to understand the adsorption isotherm, and the maximum adsorption capacity was 929.16 mg/g. The adsorption reaction is endothermic and occurs spontaneously.
