Plant-derived hybrid coatings as adsorption layers for uranium adsorption from seawater with high performance

It is critical for resource sustainability and environmental security to develop simple and dependable seawater uranium (VI) (U(VI)) enrichment technology. Membrane materials show excellent performance in the field of adsorption due to their pore structure and recyclability. In this study, a functional coating primarily composed of plant-derived tannic acid (TA) and polyethyleneimine was easily decorated on polyvinylidene fluoride (PVDF) microporous membranes for highly efficient uranium extraction via filtration. The synergistic effect of amino group from PEI and polyphenol structure plays an important role to achieve high adsorption capacity and rapid adsorption kinetics toward U(VI). Furthermore, the higher the molecular weight of PEI, the greater the modified membrane's adsorption capacity to U(VI). The membrane adorned with the optimized functional coating demonstrates outstanding removal rates (91%) and adsorption capacity (164.1 mg g-1 at C0 = 99.55 mg L-1) under extremely high permeate flux (11324.54 L m- 2 h-1) due to its high adsorption capacity and quick adsorption kinetics. Moreover, the functional coating also possesses excellent reusability, antifouling performance, high flux recovery rate (FRR) (similar to 98%) and low flux decay rate (FDR) (< 5%) after ten cycles. Particularly, the membrane's U(VI) adsorption capability in natural seawater can increase to 6.86 mg g- 1. Considering the facile and mild modification process, as well as the green and low costing materials, the plant-derived hybrid coatings have a great application prospect in the field of seawater U(VI) extraction.

Automated summary

It is crucial to develop a reliable and simple technology for seawater uranium extraction in order to ensure resource sustainability and environmental security. Membrane materials, with their pore structure and recyclability, have demonstrated excellent performance in adsorption. This study successfully decorated polyvinylidene fluoride (PVDF) microporous membranes with a functional coating primarily composed of plant-derived tannic acid (TA) and polyethyleneimine (PEI), and achieved highly efficient uranium extraction through filtration. The synergistic effect of the amino group from PEI and the polyphenol structure played a crucial role in achieving high adsorption capacity and rapid adsorption kinetics for U(VI). Furthermore, the molecular weight of PEI influenced the modified membrane's adsorption capacity to U(VI), with higher molecular weight leading to greater adsorption capacity.