Polyacrylic acid-functionalized graphene oxide for high-performance adsorption of gallium from aqueous solution

Graphene oxide (GO) has great potential in metal recovery and water purification owing to their high surface area, abundant hydroxyl (-OH) and carboxyl (-COOH) groups. To fully understand the influence of the dispersity of GO on the adsorption capacity of metal ions, a series of polyacrylic acid (PAA) function-alized GO (PAA/GO) composites with different dispersity were prepared. The charge density of the PAA/GO composites were much higher than that of the untreated GO in acidic conditions, demonstrating a significant improvement of dispersibility by introducing PAA on the surfaces. Moreover, recovery of gallium by employing the PAA/GO composites as adsorbent were studied. The maximum adsorption capacity towards gallium ions of the adsorbent can reach 196.84 mg.g(-1), much higher than that of other commercially available resins (CL-P204, P507). This superiority could be attributed to the abundant -COOH groups on the surfaces and the good dispersity of the PAA/GO composites. These results revealed that the PAA/GO composites could be promising adsorbents for selective adsorption and efficient recovery of Ga(III). (C) 2019 Elsevier Inc. All rights reserved.