An anti-algae adsorbent for uranium extraction: l-Arginine functionalized graphene hydrogel loaded with Ag nanoparticles

Sun

et al. 2019

Ind. Eng. Chem. Res.

Efficient removal of U(VI) from mine radioactive wastewater is important for environmental remediation and radiation protection. In this work, a new series of polyamidoxime/polydopamine-decorated graphene oxide (GO/PDA/PAO) composites were obtained by one-pot synthesis and used for the removal of U(VI) from mine radioactive wastewater. The as-synthesized GO/PDA/PAO composites (GO/PDA/PAO-0.2, GO/PDA/PAO-0.5, and GO/PDA/PAO-1) were examined by transmission electron microscopy, Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). The effects of pH, ionic strength, contact time, initial U(VI) concentration, and temperature on the adsorption behavior of U(VI) by GO/PDA/PAO were investigated. The maximum adsorption capacity of GO/PDA/PAO-0.2 was 502.5 mg/g at pH 6.0 and 298 K. The adsorption kinetics and isotherms can be well illustrated by the pseudo-second-order kinetics model and Langmuir isotherm model. The thermodynamic study indicated that the removal of U(VI) by GO/PDA/PAO-0.2 was an endothermic and spontaneous process. The interactions between GO/PDA/PAO-0.2 and U(VI) were explained based on the FT-IR and XPS analyses. Furthermore, GO/PDA/PAO was applied for U(VI) removal from mine radioactive wastewater. The concentration of U(VI) in the wastewater can be reduced to 7.28 μg/L, which is below the allowable uranium concentration for drinking water stipulated in the standard by the World Health Organization (30 μg/L).

Section: Resultsmentioning

confidence: 96%

Rational Synthesis of Polyamidoxime/Polydopamine-Decorated Graphene Oxide Composites for Efficient Uranium(VI) Removal from Mine Radioactive Wastewater

Sun

et al. 2019

Ind. Eng. Chem. Res.

“…In addition, the effects of ionic strength on the adsorption process were investigated (0.001, 0.01, and 0.1 M NaNO 3 ). The ionic strength had slight influence on the U(VI) adsorption by mGO-PP, which indicated that the adsorption of U(VI) was mainly inner-sphere surface complexation. , …”

Section: Resultsmentioning

confidence: 96%

Highly Efficient Removal of Uranium(VI) from Wastewater by Polyamidoxime/Polyethyleneimine Magnetic Graphene Oxide

et al. 2019

Highly efficient removal of U(VI) from mine radioactive wastewater has received a lot of attention. Herein, the polyamidoxime/polyethyleneimine magnetic graphene oxide (mGO-PP) adsorbent was successfully prepared by in situ polymerization of acrylonitrile on magnetic GO (mGO) covalently modified with polyethylenimine (PEI). The mGO-PP was characterized by Fourier transform infrared (FT-IR), scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, and X-ray photoelectron spectroscopy (XPS). The maximum adsorption capacity of mGO-PP toward U(VI) was 606.06 mg/g at 298 K and pH 6.0. The removal of U(VI) by mGO-PP for U(VI) was a monolayer chemisorption based on the study of the batch experiment. The calculated thermodynamic parameters indicated that the removal of U(VI) by mGO-PP was a spontaneous and endothermic process. The adsorption mechanism of mGO-PP toward U(VI) was explored by FT-IR and XPS analyses. Furthermore, the removal rate of U(VI) by mGO-PP is 93.68% and the K d value for U(VI) is 444.73 L/g in actual mine radioactive wastewater, and the residual U(VI) concentration (6.37 μg/L) in wastewater was lower than the maximum permissible concentration of uranium in drinking water (30 μg/L) (World Health Organization). This indicated that the mGO-PP composite is a promising adsorbent for efficient removal of U(VI) from practical mine radioactive wastewater.

“… [25] Broad strong bands centered at around 1207 cm −1 for FG/Boc‐48 h and 1181 cm −1 for FG/Arg‐48 h were assigned to C−F stretching vibration (≈1200 cm −1 ) and C−N vibration (1000–1250 cm −1 ). [ 30 , 31 ] The intensity ratio (>1.5) of the bands attributed to aromatic graphene and C−F stretching vibration in FG/Arg‐48 h_K and FG/Arg‐48 h indicated extensive graphitization and effective defluorination of the functionalized FG (Figure S2a). All the FTIR spectra are presented in Figure S2b.…”

Section: Resultsmentioning

confidence: 99%

Graphene with Covalently Grafted Amino Acid as a Route Toward Eco‐Friendly and Sustainable Supercapacitors

et al. 2021

Eco‐friendly, electrochemically active electrode materials based on covalent graphene derivatives offer enormous potential for energy storage applications. However, covalent grafting of functional groups onto the graphene surface is challenging due to its low reactivity. Here, fluorographene chemistry was employed to graft an arginine moiety via its guanidine group homogeneously on both sides of graphene. By tuning the reaction conditions and adding a non‐toxic pore‐forming agent, an optimum degree of functionalization and hierarchical porosity was achieved in the material. This tripled the specific surface area and yielded a high capacitance value of approximately 390 F g−1 at a current density of 0.25 A g−1. The applicability of the electrode material was investigated under typical operating conditions by testing an assembled supercapacitor device for up to 30000 charging/discharging cycles, revealing capacitance retention of 82.3 %. This work enables the preparation of graphene derivatives with covalently grafted amino acids for technologically important applications, such as supercapacitor‐based energy storage.