Graphene oxide encapsulated polyvinyl alcohol/sodium alginate hydrogel microspheres for Cu (II) and U (VI) removal

• Published in: Ecotoxicology and environmental safety Vol. 158; pp. 309 - 318
• Main Authors: Yi, Xiaofeng, Sun, Fuliang, Han, Zhenhua, Han, Fuhao, He, Jiarui, Ou, Minrui, Gu, Junjie, Xu, Xiaoping
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 30.08.2018
• Subjects: Copper; Graphene oxide; Polyvinyl alcohol; Sodium alginate; Uranium; Graphene oxide; Polyvinyl alcohol; Uranium; Sodium alginate; Copper
• ISSN: 0147-6513; 1090-2414; 1090-2414
• DOI: 10.1016/j.ecoenv.2018.04.039

In this work, a novel sodium alginate (SA)/polyvinyl alcohol (PVA)/graphene oxide (GO) hydrogel microspheres were prepared by a simple method. Sodium alginate was physically crosslinked by Ca2+; GO was encapsulated into the composite to strengthen the hydrogels; PVA played a significant role in well dispersing of GO in SA. The SA/PVA/GO (SPG) hydrogels were employed as an efficient adsorbent for removal of Cu (II) and U (VI) from aqueous solution. Batch experiments with the subject of the pH, initial metal ion concentration, competing ions and contact time were investigated. Structure characterization was successfully conducted by FTIR, SEM, EDX, BET and XPS. Furthermore, the sorption kinetics of Cu2+ and UO22+ followed pseudo-second order model and exhibited 3-stage intraparticle diffusion model. Equilibrium data were best described by Langmuir model and the obtained maximum adsorption capacities of SPG hydrogel microspheres for Cu2+ and UO22+ were 247.16 and 403.78 mg/g, respectively. The difference in adsorption capacity can be confirmed by the percentage of elements in EDX spectra and the intension of peak of elements in XPS spectra. The SPG sorbent exhibited excellent reusability after 5 adsorption-desorption cycles. All results suggested that the prepared adsorbents could be considered as effective and promising materials for removal of Cu (II) and U (VI) in wastewater. The percentage of elements obtained from EDX spectra and the intension of XPS peak of elements demonstrated that the adsorption capacity of the prepared sorbent for U (VI) is much higher than for Cu (II), which was in concert with the results we calculated from Langmuir equation. [Display omitted] •A novel GO encapsulated PVA/SA homogeneous hydrogel adsorbent was first prepared.•High removal efficiency for Cu (II) and U (VI) was observed for the prepared sorbent.•The adsorption followed pseudo-second order kinetic model.•The adsorption fitted well with the Langmuir isotherm model.