Zwitterion Functionalized Graphene Oxide/Polyacrylamide/Polyacrylic Acid Hydrogels with Photothermal Conversion and Antibacterial Properties for Highly Efficient Uranium Extraction from Seawater

Abstract

In this study, graphene oxide (GO) and polyacrylamide/polyacrylic acid (PAM/PAA) are used to prepare hydrogels with photothermal conversion properties for highly efficient uranium extraction from seawater. Zwitterionic 2‐methacryloyloxy ethyl phosphorylcholine (MPC) is introduced in the PAM/PAA/GO hydrogel to obtain PAM/PAA/GO/MPC (PAGM), exhibiting good antibacterial properties. PAGM demonstrates efficient and specific adsorption of uranium (VI) (U(VI)). Under light conditions, the adsorption capacity of PAGM reaches 196.12 mg g−1 (pH = 8, t = 600 min, C0 = 99.8 mg L−1, m/v = 0.5 g L−1). The adsorption capacity is only 160.29 mg g−1 under dark conditions (pH = 8, t = 600 min, C0 = 99.8 mg L−1, m/v = 0.5 g L−1). The adsorption capacity of light is 22.5% higher than that of dark. The adsorption process is fitted using the Langmuir and pseudo‐second‐order models. Furthermore, PAGM exhibits good repeatability and stability after five adsorption–desorption cycles. PAGM exhibits a U(VI) adsorption capacity of 6.1 mg g−1 after storage for one month in natural seawater. The X‐ray photoelectron spectroscopy (XPS) results demonstrate that the coordination of the amino, carboxyl, and hydroxyl groups with U(VI) is the primary mechanism of U(VI) adsorption. The mechanism is confirmed through detailed density functional theory calculations. PAGM demonstrates durability, high efficiency, photothermal conversion properties, and antibacterial properties. Thus, it is a promising candidate for uranium extraction from seawater.

Strengthening Fe(II)/Fe(III) Dynamic Cycling by Surface Sulfation to Achieve Efficient Electrochemical Uranium Extraction at Ultralow Cell Voltage

“…2− on the S-NRI surface (Figure S6). 12,31 As time goes by, the binding energy of Fe−SO 4 2− bonds moves to a lower direction at about 0.9 eV, which may be attributed to the strong chemical interaction between Fe−SO 4 2− bonds and UO 2 2+ due to the formation of U(VI)−sulfate surface complexes. 32 For O 1s XPS spectra of S-NRI, the peaks at 535.6, 531.7, and 530.3 eV are considered as adsorbed water, M−OH bonds, and metal oxide (M−O bonds), respectively (Figure 2c).…”

“…Uranium is an element with radiotoxicity and chemical toxicity that is widely present in the natural environment . Uranium entering natural water bodies can cause uranium pollution of groundwater or surface water, thereby posing potential ecological and human health risks. , In addition, uranium is also an important element in nuclear energy and it is a very valuable recyclable resource. , The ocean (about 4.5 billion tons of uranium) and the toxic wastewater from uranium mining contain abundant uranium resources. , Therefore, how to realize the efficient extraction of uranium resources from seawater (3 ppb) and wastewater (5–50 ppm) is crucial for the development of uranium recycling and wastewater treatment. − Traditional physical methods still face the challenges of limited active sites of the adsorbent, slow diffusion of uranyl ions, and Coulombic repulsion of competitive ions. − …”

“…2,3 In addition, uranium is also an important element in nuclear energy and it is a very valuable recyclable resource. 4,5 The ocean (about 4.5 billion tons of uranium) and the toxic wastewater from uranium mining contain abundant uranium resources. 6,7 Therefore, how to realize the efficient extraction of uranium resources from seawater (3 ppb) and wastewater (5−50 ppm) is crucial for the development of uranium recycling and wastewater treatment.…”

Selective Anchoring by Surface Sulfur Species Coupled with Rapid Interface Electron Transfer for Ultrahigh Capacity Extraction of Uranium from Seawater

“…How to improve the adsorption selectivity, enhance the extraction capacity, and ensure the structural stability of adsorbents are the key to achieve efficient uranium recovery. 8 Transitionmetal-based compound nanomaterials have been developed rapidly because of their advantages, such as simple preparation, low cost, and the sorption/reduction synergistic effect. 9 Thereinto, metal sulfides have attracted much attention owing to their high specific surface area, excellent electrical conductivity, and open structure, which can provide sufficient active sites and fast network electron transport.…”

“…Unfortunately, these adsorption materials still face difficulties in balancing their adsorption capacity, high selectivity, and structural stability. How to improve the adsorption selectivity, enhance the extraction capacity, and ensure the structural stability of adsorbents are the key to achieve efficient uranium recovery . Transition-metal-based compound nanomaterials have been developed rapidly because of their advantages, such as simple preparation, low cost, and the sorption/reduction synergistic effect .…”