Persimmon tannin/graphene oxide composites: Fabrication and superior adsorption of germanium ions in aqueous solution

Herein, a new persimmon tannin/graphene oxide (GO-PT-6Glu) composite was fabricated through one-step cross-linking method. The as-prepared GO-PT-6Glu has substantial phenolic hydroxyl groups (up to 5.23 mmol g(-1)) by introducing water-soluble PT (up to 5.50 mmol g(-1)) on the GO, which provides the opportunity to use it as an adsorption material to recover germanium. The GO-PT-6Glu was then used to adsorb germanium from aqueous solution and showed the highest than among currently reported adsorption capacity (117.38 mg g(-1)). Simultaneously, it exhibits excellent cycle performance to adsorb germanium still with a high adsorption efficiency (up to 81.42%) after 5 adsorption-desorption cycles. More importantly, the GO-PT-6Glu showed superior selectivity towards Ge(IV) as compared to As(Ill) (Cl-/SO42-/PO43-), in spite of the concentration of As(III) (Cl-/SO42-/PO43-) was 100 times higher than that of Ge(IV). Taking advantages of its low cost, selective adsorption, as well as environmental protection and high adsorption, the GO-PT-6Glu is expected to be the most promising material in recovery of Ge(IV) from water containing As(III). (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.