Bioinspired green tea waste/graphene aerogel for solar-enhanced uranium extraction from seawater

Abstract

Natural seawater is recognized to be the most promising source to satisfy the growth demands on uranium. The currently proposed seawater uranium extraction strategy faces great challenges, including the limited adsorption capacity, slow kinetics, poor selectivity and severe fouling under complex marine conditions. Inspired by water transpiration, nutrient transport and porous structure of Salvinia cuccullata, we designed and fabricated a green tea waste/graphene aerogel (GDT) with Salvinia cuccullata root-like structures and photothermal conversion characteristics for uranium capture. This biomimetic GDT exhibited efficient photothermal conversion with fast water evaporation rate (2.72 kg m−2 h−1) under 1 sun irradiation, which facilitated rapid uranium diffusion and extraction, leading to a 1.22-fold increase in adsorption capacity for GDT in natural seawater. The uranium extraction capacity on GDT achieved 11.9 mg/g from natural seawater in a month accompanied with great selectivity. Moreover, its excellent reusability of 85.1% after 10 cycles of adsorption-regeneration and good antifouling ability endowed the GDT a long service life for practical application. This work offers a novel strategy for oceanic uranium extraction, and opens a new avenue for marine resources mining.